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Mid-IR DFB Interband Cascade Laser 2900 – 4000nm

We divide our lasers into wavelength regions.

So when we say range 2900nm to 4000nm that is a region to classify our lasers. But then the individual laser will be centered at an specific wavelength. Usually our lasers tune a few nm, the higher the wl the more nm that the laser can be tuned, but is always below 5nm if tuned only with current, even less (depending on the wl).

“so your stating that this laser will emit at 2800 with the same performance.”->no we did not stated that.

What is the method to shift the wavelength? ->usually by current, and it can be done with temperature as well.

in our implementation will will want to fix this emission.-> if they want a fixed wl, then they need that temperature and current of the laser stay stable.

can this be done by your company in the event that we implement this into our systems?-> that has to be controlled by the laser driver, we do not manufacture laser drivers,

and is there OEM pricing available? -> which exact wavelength?, how many units?, is TO66 mounting ok for them?

Can I also get pricing information as well as what systems need to be installed to support this,

ie heat sinK? -> all our lasers are provided with an internal TEC, which controls the temperature.

In labs and universities we sometimes deliver an external heatsink (see attached “cube.pdf” file) which helps in the setup and fine control of temperature. Would that be useful for your customer?

controlled temperature? what is the electrical diagram look like to implement this type of emitter,-> see attached electric circuits.

what is the emission FOV?-> The expected degrees of the emitted beam are the below ones, please note that this can change with the individual laser, but is a good approximation.

As well we can offer collimated beam mounted in the heatsink if needed (usually requested by University students)

 

Cubic mounts forTO5 andTO66 headers

electric circuit to connect a LD 2 of 2

electric circuit to connect a LD

 

 

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Raman spectroscopy in VIS/NIR of a rotating sample excited by a CW laser with AOM modulator

Raman spectroscopy in VIS/NIR of a rotating sample excited by a CW laser with external modulator

 

Raman spectroscopy in VIS NIR of a rotating sample excited by a CW laser with AOM modulator

Conditions
 Sample should be pumped only during the time it crosses the laser beam (600 – 60 000rpm)
– repetition rate 10Hz – 1kHz (1 – 100ms period) changing during experiment
– duty cycle 0,7% or larger (constant, independent of rep. rate for a given sample)
– pulse width 7µs – ~1ms, determined by rep. rate and duty cycle
 External modulation
– fast binary digital (ON/OFF) with a high extinction ratio
– slow power control, at least one of following types (in priority order)
– by computer (USB, RS232, etc.)
– analog modulation
– manual

 

 

Requirements
 Laser wavelength (+/- 2 nm): 405, 532, 638, and 785 nm (DPSS or VBG-diode, linearly polarized)
main operation wavelengths – 405 and 638nm, next 532nm, 785nm – only a useful future option
 Insertion losses: ≤ 1dB (≥ 80% diffraction efficiency)
 Polychromatic operation (quote all possible configurations!):
individual AOM for each laser
and alternatives, e.g.,
# A UV-Vis-NIR AOM for 405 / 532 / 638 /785 (a bit worse performance for 785nm)
# B UV-Vis AOM for 405 / 532 / 638 + NIR AOM for 785
# C UV AOM for 405 + Vis-NIR AOM for 532 / 638 / 785
# D UV-Vis AOM for 405 / 532 + Vis-NIR AOM for 638 / 785
# E UV AOM for 405 + Vis AOM for 532 / 638 + NIR AOM for 785
AOTF are usually a bit too slow
PCAOM can be used in two possible configurations
– common – combined coaxial input and output beams (Fig.1)
– may be possible too – separated input but combined coaxial output beams – a kind of
backward polychromatic deflector (preferred option to simultaneously directly combine
individual laser beams) (Fig.2)
 Digital modulation (common for all wavelengths)
external trigger TTL
rise/fall times ≤ 1µs (10-90%)
extinction ratio ≥ 1000:1 (30dB)
trigger gate (option) fast, ~10µs interlock
 Laser power control (individual for each wavelengths)
power control range 1-100%, still acceptable option 10-100%
computer control USB interface (RS232 – possible option)
analog modulation bandwidth ≥ 1Hz
analog modulation control voltage 0-1V, or 0-5V, or 0-10V (either one range)
 Accuracy, induced noise, stability ≤ 1%
 Laser beam diameter (TEMoo) ~1mm, 1,5mm max
focusing can be an option to reduce switching time but only
without deterioration of insertion losses / diffraction efficiency

 

 Laser power ≤ 200mW, typ. 100mW each (CW)
Notes:
 The supplier should be an authorized sales and service representative of the original manufacturer.
 Warranty: At least one year on the complete system.
 Specify the total price including university / research discounts and sconto discount
 Comments on unique features different from competitor products would be useful

 

 

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VCSEL Laser Diode Applications

High-Power VECSELs Operating 700-800nm

Demonstration of blue semipolar GaNbased vertical-cavity surface-emitting lasers

Kent Choquette: Introduction to Vertical-Cavity Surface-Emitting Lasers (VCSELs) and Applications

 

VCSEL laser diodes are a semiconductor “vertical cavity surface emitting laser” diode that emits light in a cylindrical beam vertically from the surface of a fabricated wafer and offers significant advantages when compared to the edge-emitting lasers currently used in the majority of fiber optic communications devices.

There are two special semiconductor materials sandwiching an active layer where all the action takes place. But rather than reflective ends, in a VCSEL there are several layers of partially reflective mirrors above and below the active layer. Layers of semiconductors with differing compositions create these mirrors, and each mirror reflects an arrow range of wavelengths back in to the cavity in order to cause light emission at just one wavelength.

VCSEL laser diodes offer no speckle, banding, or other artifacts compared to edge-emitting laser diodes and are the perfect choice for illumination applications and a variety of different needs.

Benefits of VCSEL:

Scalable output power
High quality optical beam
Two available modes of operation
Continuous Wavelength (CW) or Quasi-CW mode
Pulsed mode
Higher wall-plug efficiency versus LED
Stable wavelength over temperature and low spectral width
Easy to package
No single emitter failure point
Multi-emitter increases ESD robustness and lifetime
VCSEL Applications
VCSEL technology is extending the possibilities of consumer and scientific applications including 3D facial recognition, augmented reality, automotive in-cabin sensing and automotive LiDAR.

LiDAR
The LiDAR (Light Detection And Ranging) instrument fires rapid pulses of laser light at a surface, some at up to 150,000 pulses per second. A sensor on the instrument measures the amount of time it takes for each pulse to bounce back. Light moves at a constant and known speed so the LiDAR instrument can calculate the distance between itself and the target with high accuracy. By repeating this in quick succession the insturment builds up a complex ‘map’ of the surface it is measuring. With airborne LiDAR other data must be collected to ensure accuracy. As the sensor is moving height, location and orientation of the instrument must be included to determine the position of the laser pulse at the time of sending and the time of return. This extra information is crucial to the data’s integrity. With ground based LiDAR a single GPS location can be added for each location where the instrument is set up.

Most of today’s LiDAR technologies are MEMS or rotating mirror based. These technologies include many moving parts, they are expensive to produce and have high failure rates. It’s also important to note that many LiDAR systems must operate in less than ideal climates and high-vibration environments. The right 940-nm VCSEL modular laser technology is designed to operate at the automotive AEC-Q100 Grade 1 temperature ranges from -40°C to +125°C. This technology has been deployed in the telecommunications arena for more than two decades, with very high reliability. In addition, these new VCSELs have been tested for millions of hours of equivalent operation at the power levels for long range LiDAR.

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Fabry Perot Lasers

Fabry Perot Lasers

法布里珀罗激光器

法布里·珀罗二极管激光器是最常见的二极管激光器类型。 它们在空间上是单一模式。 激光芯片的典型几何尺寸为1000µm x 500µm x 200µm(长x宽x高)。 根据芯片长度,法布里珀罗(Fabry Perot)激光器纵向运行单模或多模。

 

DFB的一般都带电子制冷功能,除了驱动激光器的引脚,还有保持激光器温度恒定的带电子制冷功能的器件, 因为只有保持激光器温度恒定,功率输出才稳定。

760nm 法布里珀罗激光可用于激光气体分析仪,用于氧传感器。规格书如下:

DFB laser diodes 760-830NM

800nm 法布里珀罗激光器的参数表,请参看如下 760nm – 830nm 规格书。

DFB laser diodes 760-830NM

1653nm 法布里珀罗激光可用于激光气体分析仪,用于甲烷传感器。规格书如下:

DFB laser diodes 1650-1850NM

1700nm 法布里珀罗激光器的参数表,参看1650nm-1850nm 规格书

DFB laser diodes 1650-1850NM

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904nm Pulse-coupled Multimode Pigtailed LD FC/APC

905nm pulse-coupled multimode laser diode output pigtail fiber sensing dedicated.
6WFC / APC optical sensor head DTS special pulse 905nm laser diode with a multimode pigtail output power
Features:
High End/Low-Cost Pulsed Laser Diodes
Single and Multi-junction devices up to 10W
Excellent Reliability
Coaxial Pigtail Package
Fully RoHS compliant
Applications:
Range finding
Surveying equipment
Weapons simulation
Laser radar
Obstacle detection
Medical
Automotive

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Double Ferrule Compression Fittings

Compression fittings are used to create leak-free tube connections easily and quickly. Double ferrule compression fittings feature an outer nut, two deformable ferrules in soft alloy or non-ferrous metals and, a tube fitting body and are available for metric and fractional tube sizes. When the fitting nut is screwed on the tube, the ferrules get deformed to create a tight seal. Swagelok and Parker are the two main players in the compression fittings market.

Compression fittings allow the connection of two imperial tubes (or fractional tubes), two metric tubes or, also, the connection of a metric tube at one end and a fractional/imperial tube at the other end.

A common size range is between 1/16″ and 2″ for fractional sizes and between 2 and 50 mm for metric sizes).

Compression tube fittings are rated to the maximum working pressure of the tubing to be installed.

Double ferrule compression tube fittings are largely used across multiple industries, such as downstream petrochemical, pulp & paper, laboratories, aeronautical and shipbuilding, defense, power generation, semiconductors manufacturing, and heavy industries.

 

 

 

HOW TO INSTALL COMPRESSION FITTINGS

The tube has to be inserted into the fitting and the nut has to be screwed. By doing this, the back ferrule advances axially towards the front ferrule and applies an effective grip on the tube.

The ferrule is deformed, compressed and clamped around the tube creating a very tight seal able to withstand the nominal pressure of the tubing.

The two-ferrule design compensates the tolerances in tube diameter, wall, thickness, and material hardness, giving the connection exceptional leak-free performance (without impacting the mechanical properties of the tubing: the back ferrule moves according to a predefined path without reducing or stressing the inner diameter of the tube).

The connecting tube, at the outlet of the fitting, can be screwed or welded on the compression tube fittings (depending on fitting end type). Multiple options are available in terms of screwed ends (NPT, ISO, etc).

A joint made with a ferrule fitting can be disassembled for maintenance (spare ferrules and nuts are available).

By using some basic tools, provided by compression tube fittings manufacturers, the installation is smooth and quick. No welding is required.

As shown in the video above, a proper force shall be applied to the nut when screwing it on the tube otherwise the fitting may get damaged and the connection might leak. It is recommended to tighten the nut manually at first and then use an appropriate wrench.

COMPRESSION FITTINGS TYPES
Compression tube fittings (ferrule) can be grouped into the following families:

Connectors (male connector, female connector, bulkhead male connector, bulkhead female connector, butt weld pipe connector, socket weld tube connectors)
Male and female elbows
End closures (tube, fitting)
Reducers
Tees (male run tee, female-run tee, male branch tees, female branch tees)
Unions
All these tube fittings are shown in the image below:

 

 

 

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Chromacity and Scientifica join forces on laser microscopy

Chromacity and Scientifica join forces on laser microscopy

Companies sign partnership to provide ultrafast laser sources for multiphoton imaging applications

Ultrafast laser systems developer Chromacity has established a partnership with Scientifica, a provider of laboratory equipment. The agreement means that Chromacity’s lasers are now offered as a light source option in Scientifica’s range of microscopy solutions.
With operations in the United Kingdom and the United States, Scientifica designs, manufactures and supplies microscopes to the research community worldwide.

The company is now offering its customers the option to use a Chromacity laser, particularly for multiphoton microscopy – a powerful technique used to image structures deep within thick samples, making it suitable for in vitro and in vivo imaging.

Christian Wilms, R&D Manager at Scientifica, commented, “Life scientists using multiphoton microscopy in their research are always striving to look deeper into living tissue. The recent introduction of longer wavelength fluorescent markers has paved the way towards such deeper imaging, by allowing researchers to use longer wavelength excitation lasers, which penetrate deeper into biological tissue without causing damage to those tissues.”

Multiphoton microscopy

Modern research practices like multiphoton microscopy often make use of expensive tunable solid state lasers, which often fail to generate consistent powers and can distort the quality of the data and the image being acquired. Costing an order of magnitude less than tunable solutions, Chromacity provides a range of air-cooled ultrafast ytterbium fibre-based lasers, operating at fixed wavelengths and combining high power with very short pulsewidths to generate clear, high-resolution images.

Shahida Imani, Chromacity CEO, said, “We are delighted to partner with a cutting-edge equipment provider like Scientifica, whose global customers can now benefit from the high power, reliability and competitive price point of our lasers. We look forward to working closely with our colleagues at Scientifica to deliver microscopy solutions that will help push the next breakthroughs in scientific research.”

 

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nanoplus ICLs and MIR LEDs

The latest expansion of growth capacities enabled the exploration of various design variations within the active region of our Interband Cascade Lasers (ICLs). Together with a revised chip design we were able to extend the maximum operation temperature for continuous wave (cw) operation well above room temperature for wavelengths from 4.5 µm up to 5.5 µm.

At an operation temperature of 20°C a typical output power of 5mW is reached while the electrical driving power at threshold is as low as 150 mW. Typical characteristics of devices in the 46xx and 52xx nm wavelength range are shown in the graphs below.

 

 

20 years of nanoplus – DFB lasers revolutionize high precision gas sensing

On October 1st, 1998, nanoplus started with the production of laterally coupled distributed feedback lasers. With unforeseen wavelength precision, stability and diversity nanoplus DFB lasers paved the way for numerous state-of-the-art gas sensing applications in science and industry.

A strong belief in the driving force of innovative technological development, ambitious company growth and passionate dedication shaped the past 20 years of nanoplus.

Since its beginnings, nanoplus has committed to continuously developing its DFB laser technology for the gas sensing market. The continued research effort has led to various pioneering lasers with cutting-edge specifications.

The growing array of top-grade applications relying on nanoplus lasers is overwhelming. Most recently, nanoplus DFB laser technology is e. g. used to carry out isotope selective CO2 measurement in breath gas analysis. In another instrument it monitors sulphur dioxide to help recycle heavily contaminated activated charcoal and the International Space Station (ISS) observes in real-time its formaldehyde level with nanoplus lasers. In the future nanoplus devices will measure gases in next-generation space systems or detect the alcohol blood level of American drivers.

Convinced of the power of its DFB laser technology and the large market for it, nanoplus started to heavily expand its production capacities very early. Today, nanoplus is well set up to cater the needs of its growing number of industrial customers. It offers vast clean room facilities with an almost fully automated process line and consisting of an impressive ultramodern machinery fleet.

At the same time, nanoplus has always put emphasis on optimizing its production processes to live up to its customers strict requirements. At this end, nanoplus has introduced a tight quality management system certified by ISO 9001:2015 and ISO 14001:2015.

Along with the massive production expansion, nanoplus has enlarged its R&D and production manpower continuously over the past years. This knowledge basis together with the outstanding enthusiasm, motivation and team spirit of all employees helped nanoplus to face the organizational challenges involved in the development from small start-up into a reliable partner for industrial and scientific customers.

 

 

 

After having successfully introduced interband cascade lasers for various gas sensing applications in the MIR wavelength region, nanoplus now proudly presents its new MIR light emitting diodes based on the interband cascade technology.

The new high performance ICLED devices offer continuous wave operation at room temperature with output powers exceeding 1 mW at an emission wavelength centered around 3.2 µm. Other wavelengths are available upon request, making these devices highly interesting for methane and CO2 sensing.

The new ICLED devices are packaged into cost effective ceramic surface mountable packages with low thermal resistance, Thus, the ICLED technology provides a real alternative to previously available solutions like thermal emitters typically used in NDIR spectroscopy.

 

Surface mountable nanoplus MIR ICLED for continuous wave operation in a ceramic package

 

Continuous wave operation light-current-voltage characteristics of an MIR-ICLED

Spectrum of a mounted MIR-ICLED

 

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Laser Scanning

Laser Scanning

 

3D Laser Scanning Slave Cabins on Plantations in Natchitoches

US ICOMOS interns, Ina Sthapit and Sukrit Sen who are currently working under Jason Church are documenting few of the existing slave cabins left in the plantations around Nachitoches. Last week while they laser scanned the two cabins in the Oakland Plantation, they met up with Mr. Elvin Shields who was brought up in one of these cabins and is helping them develop an oral history about the life of a tenant farmer and their association with these cabins.

He talked about various aspects starting from the arrival of the slaves in the ports of America to their conversion into share-croppers. He talked about their whereabouts in these cabins, and why they have disappeared today. He also mentioned about their social life and how they spend their free time after a rigorous week in the plantations. Shields gave them an insight of a broader intangible aspect that these cabins are attached to and add to its historic value.

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Mid-Infrared InP-Based Discrete Mode Laser Diodes

Abstract
Low cost, compact and robust single mode semiconductor laser diodes emitting at λ ∼ 1.6–2.1 μm are highly desirable as light sources for trace gas spectroscopy and an increasing number of other applications, such as, high data-rate communications over hollow core photonic crystal fibre, noninvasive optical blood glucose monitoring. Indium phosphide based light sources provide a solid and flexible base for mid-infrared semiconductor diode lasers. This chapter provides an overview of the current state of the art in discrete mode InGaAs/InP long-wavelength quantum-well lasers emitting in the 1.6–2.1 μm wavelength range. The discrete mode laser is essentially a regrowth free modified ridge waveguide Fabry-Pérot laser whose optical spectrum has a single wavelength mode. High-performance and cost-effective mid-infrared DM laser diode sources are well suited to a wide range of sensor applications. The current state of the art will also be outlined in this chapter.

 

Keywords

  • semiconductor laser
  • mid-infrared sources
  • single mode laser
  • strained quantum-well
  • absorption spectroscopy

1. Introduction

Low cost single mode semiconductor laser diodes emitting at wavelengths, λ, in the 1.6–2.1 μm wavelength range are highly desirable as light sources for trace gas spectroscopy due to the strong absorption bands [1] in this spectral region. Compared to conventionally used systems based on electrochemical point sensors, tuneable diode laser absorption spectroscopy (TDLAS) offers a number of benefits for the detection of gases such as; rapid response time, long term stability, high selectivity and sensitivity, rugged systems and measurement capability over long distances using open path systems [2]. TDLAS is based on the molecular rotational-vibrational absorption of gases that produce distinct peaks in the near to mid-infrared (IR) spectral range. These molecule resonances cause characteristic ‘fingerprints’ by selective absorption of laser light as the wavelength is tuned by changing the laser bias current or heat sink temperature. Great interest is due to the strong absorption lines of various important gases, such as methane (1.665 μm), hydrogen chloride (1.743 μm), and nitrous oxide (1.795 μm), in this wavelength range. Two pertinent greenhouse gases, water vapour (H2O) and carbon dioxide (CO2), have strong absorption bands at wavelengths centred around 1.877 and 2.004 μm respectively and are shown in Figure 1. There is also an increasing number of other applications, such as high data-rate communications over hollow core photonic crystal fibre [3456] and noninvasive optical blood glucose monitoring [7] which also require compact and robust low-cost laser sources emitting in the 1.6–2.1 μm wavelength range.

Figure 1.

Absorption spectra of two important greenhouse gases CO2 and H2O, with strong absorption lines in the near-to-mid-IR extracted from the HITRAN database [1].

Semiconductor laser diode materials with light emission in the 1.6–2.1 μm wavelength range include indium phosphide (InP) and the gallium antimonide (GaSb) material systems. It must be noted that cost sensitivity is a significant issue for many of these applications and in order to keep the laser chip cost down the InP material is often preferred over the GaSb material system for emission in the mid-IR region. In comparison with the GaSb material platform, the processing technologies for InP-based materials are more mature as they were developed for telecommunications lasers. In addition, superior substrate quality, lower substrate cost, better thermal performance and mature growth methods make InP-based lasers attractive candidates for light sources in this wavelength region [89101112131415]. The III-V compound semiconductor material system (AlGaIn)-(AsP) constitutes an ideal basis for the realization of diode lasers in this wavelength region [16]. InGaAs, either lattice matched to InP or deliberately strained, can be used for the active layer with a direct band gap between 1.1 and 2.3 μm. Recently InP-based type-II QWs have extended the wavelength up to 3 μm [17] which opens up another important wavelength region for the fabrication of lower cost lasers for sensing applications.

This chapter begins with an overview of mid-IR single mode laser diodes and then outlines the state of the art in InP based mid-IR discrete mode laser diodes.

2. Overview of the state of the art in mid-IR single mode laser diodes

In this section an overview of the current state of the art in compact monolithic single mode laser diodes emitting in the 2.0 μm spectral region will be outlined. Focusing on monolithic chips, external cavity laser devices are not included here. The review will start with an overview of the material systems available for the laser active region emission in the 2 μm spectral region. To date single mode semiconductor lasers have been demonstrated in both the GaSb and indium InP material systems. Both material systems have their pros and cons and an overview of the various technology implementations for achieving single wavelength mode operation in each material system is shown.

2.1 Gallium antimonide (GaSb) laser diodes

The III-V compound semiconductor material system (AlGaIn)(AsSb) constitutes an alternative basis for the realisation of diode lasers in the mid-IR. GaInAsSb is either latticed matched to GaSb substrates or strained and is used as the active layer with a direct bandgap transition covering the λ ∼ 1.8–3.4 μm wavelength region. For the barrier and cladding layers, AlGaAsSb is well suited because of its larger bandgap energy and lower refractive index compared to GaInAsSb. Molecular-beam epitaxy (MBE) is the method of choice and most widely used in the wafer growth. The laser structures are grown on (100)-orientated n-doped GaSb substrates but due to the lower demand for GaSb substrates compared to InP the growth cost is higher and substrate quality lower. Conventional fabrication of distributed-feedback (DFB) lasers incorporating buried gratings for longitudinal mode selection is challenging in the GaSb material system due to the difficulty of epitaxial regrowth with the high Al concentrations in the cladding layers. Separately, processing options are quite limited for GaSb due to the cladding material being hygroscopic.

2.1.1 Laterally coupled distributed-feedback

A proposed method for DFB fabrication which was recently demonstrated by the Jet Propulsion Laboratory (JPL) [18], makes use of Bragg gratings etched alongside a ridge waveguide to form a laterally coupled distributed-feedback (LC-DFB) as shown in Figure 2This approach enables fabrication of single-longitudinal-mode laser following a single epitaxial growth process.

Figure 2.

(a) Cross-section scanning-electron micrograph of a 3-μm-wide laser ridge topped with a titanium-platinum-gold contact layer. (b) Top view of the LC-DFB laser structure, with a cross section of the grating (inset) [18].

Characteristics of the LC-DFB laser are as follows; at a heat sink temperature of −10°C they demonstrate a single mode emission in the 2054 nm region with an SMSR > 30 dB and ex-facet power exceeding 80 mW. This is the highest reported power from a DFB laser at 2 μm. The wavelength shift with current and temperature is reported to be 5.39 × 10−3 nm/mA and 0.2 nm/oC [19]. They also demonstrated LC-DFB laser linewidths of 1.4 MHz and 900 kHz for 500 and 10 ms observation times, respectively. The linewidths were derived from the frequency-noise power-spectral density measured using a Fabry-Perot interferometer.

2.1.2 Lateral metal grating DFB

Ridge waveguide GaSb DFB lasers have also been fabricated by the University of Wurzburg and commercialised by the German company NanoPlus which employ a lateral metal grating at the side of the ridge [20] as depicted in Figure 3. The metal gratings provide strong feedback but generate additional absorption loss in the laser cavity hence the ex-facet laser power is limited to ∼10 mW levels.

 

Figure 3.
Schematic diagram of the ridge waveguide metal grating DFB [20].
A single mode emission at 2 μm with a side mode suppression ratio of 31 dB is demonstrated in [20] and output power in the 8 mW region. The wavelength tuning rate with temperature is 0.2 nm/oC. Reported linewidth measurements are in the 0.3–0.5 MHz region [21].

2.2 Indium phosphide (InP) laser diodes
To extend the emission wavelength from λ ∼ 1.55–2.1 μm in the InxGa1-xAs material system compressive strain is applied by increasing the indium (In) composition. Figure 6 shows the calculated bandgap wavelength (λg (μm) = 1.2407/Eg (eV)) for a bulk InxGa1-xAs layer on InP as a function of In composition. As shown in Figure 2, a compressive strain larger than 1% is required to obtain a bandgap wavelength longer than 2 μm. Also shown in Figure 4 is the experimentally measured quantum well photoluminescence peak wavelength for four separate active regions with the In composition varied. When a quantum well structure is used instead of a bulk layer, the bandgap wavelength becomes smaller because of the quantum size effect on the bandgap energy. Therefore larger strain is required for InxGa1-xAs quantum wells (QWs) to obtain the same bandgap wavelength as bulk InxGa1-xAs [14].

Figure 4.

Calculated bandgap wavelength for InGaAs on InP as a function of In composition. The upper horizontal axis shows the mismatch strain of InGaAs with respect to InP. Red dashed line indicates the lattice constant of InP 5.869A [13].

2.2.1 InP-DFB

InP-based DFB lasers have been extensively developed with wavelengths at 1.3 and 1.55 μm for fibre optic communications over the last three decades. Similar processing techniques can be used for fabrication of single mode lasers operating in the 2 μm wavelength range. NTT-Japan demonstrated a DFB laser with an emission wavelength of 2.051 μm and output power of 10 mW [22]. A schematic of their buried heterostructure DFB grating is shown in Figure 5. The DFB grating was buried and required two regrowth stages after grating formation. There are no reported measurements on the spectral linewidths but they are expected to be in the 2 MHz range. The ex-facet power of 10 mW was improved on in a subsequent paper [23] with a value of ∼20 mW reported. The wavelength shift with current and temperature is reported to be 0.0025 nm/mA and 0.125 nm/oC [24].

Figure 5.
Schematic of BH-DFB laser diode [23].
2.2.2 Vertical-cavity surface-emitting laser
Light propagation and emission normal to the semiconductor layer structure is characteristic of a vertical-cavity surface-emitting laser (VCSEL) [25]. The main feature of the VCSEL design is the regrown buried tunnel junction (BTJ) (see Figure 6), which accomplishes current confinement and wave guiding. The active region contains five heavily compressively strained InGaAs-quantum wells separated by tensile strained barriers of InGaAIAs. Current is injected through a contact pad on the epitaxial mirror and the gold heat sink via the n + doped contact layers [25]. The n-doped epitaxial mirror reflectivity of the front mirror of 99.4% and back mirror reflectivity was 99.9%. The dielectric DBR is combined with an integrated electroplated Au-heat sink and a buried tunnel junction. VCSEL’s emitting in the 2 μm region have been demonstrated by the Technical University Munich and commercialised by VERTILAS in the InP material system [25] however the ex-facet power levels from this technology is limited to <1 mW. Due to the very short laser cavity spectral linewidths from VCSEL devices are typically >20 MHz [26], and show high tuning rates of 0.67 nm/mA and 1.5 nm/oC.

Figure 6.

Schematic of VCSEL laser diode [26].

2.2.3 InP-discrete mode laser diode

Discrete mode (DM) technology is Eblana Photonics proprietary method of manufacturing single mode lasers. Single wavelength operation in DM lasers is achieved by introducing index perturbations in the form of etched features positioned at a number of sites distributed along the ridge waveguide laser cavity as shown in Figure 7. Eblana has recently fabricated single mode lasers in the 2 μm spectral region [13]. The spectral linewidths for DM laser emitting at 2.0 μm is 1 MHz. The ex-facet power of 5 mW was measured and the wavelength shift with current and temperature is reported to be 0.0025 nm/mA and 0.125 nm/°C [13].

Figure 7.
Electron micrograph of Fabry Perot laser cavity (top left) and DM laser, fabricated by etching slots into laser ridge (bottom left) along with spectral characteristics of typical mid-IR laser with and without etched features (top and bottom right respectively).

3. Mid-IR DM laser
3.1 Design of InP ridge waveguide FP lasers
A typical InP based Type-I laser structure for an emission wavelength of 1.6–2.1 μm is shown in Figure 8 [14]. For most of the laser structures reported on in Section 3, two to three compressively strained QWs are used as the active region with a width of 10 nm. They are separated by 15–30 nm thick InxGa1-xAs barrier layers which are either lattice matched to the InP substrate or tensile strained in order to reduce the average strain in the active region. The active region is sandwiched between two 200 nm-thick InGaAsP separate confinement guide layers with a bandgap wavelength of λg = 1.3 μm which also acts as an etch stop layer for ridge waveguide definition. A 1800 nm thick p-InP layer is grown on top of the separate confinement heterostructure followed by a 200 nm thick highly p-doped InxGa1-xAs contact layer [3].

Figure 8.

Direct bandgap profile of an InP-based type-I laser structure with an emission wavelength of 2.1 μm [14].

For the results shown below, four laser structures with varying In compositions were grown on 75 mm diameter n-type (100)-InP substrates in a metal-organic vapour-phase epitaxy reactor at low pressure. The overlapped photoluminescence spectra for the four wafers are shown in Figure 9 measured at room temperature. The sharp peaks indicate high material quality with low defects.

Figure 9.

Overlapped measured photoluminescence spectra at 25°C for four wafers with varying In composition.

The optical waveguiding properties of the ridge waveguide structure was determined by carrying out 2-D numerical simulations and one example for the 2 μm wafer (In = 0.74) is shown in Figure 10. The modal analysis of the structure showed that no higher order lateral modes are supported when the ridge width is 2 μm and that the calculated effective index for the waveguide is 3.2. This effective index is used to calculate the grating pattern spacing required to give single mode emission at the target wavelength which will be described below [3].

Figure 10.

2D simulation of a ridge waveguide laser diode.

3.1.1 FP laser fabrication

In order to make good single longitudinal mode lasers, the ability to fabricate uniform, highly reliable FP lasers is essential and complete wafers of FP lasers were processed for material evaluation. For the laser to operate in a single lateral mode, control of the ridge width is critical. Simulations showed that a 2 μm wide ridge results in a stable transverse mode. The waveguide was realised using inductive coupled plasma dry etching, the dry etch chemistry used was Cl/N2 followed by a short wet-etch to remove surface roughness. Electrical contacting was achieved using conventional metals (Ti/Pt/Au) and SiO2 as an insulator for contact definition on the heavily doped (p ∼ 2 × 1019 cm−3) p+-InGaAs capped layer. A scanning electron microscope (SEM) image of the fabricated ridge waveguide is depicted in Figure 11a. Finally the wafers were thinned to 150 μm by mechanical polishing and the n-metal electrode applied [3]. A completed wafer is shown in Figure 11b. Subsequently bars were cleaved into 900 μm cavity lengths and the front and back facets coated 20 and 95% respectively.

 

Figure 11.

(a) SEM image of a ridge waveguide FP laser diode. (b) Picture of a processed 3-inch InP wafer.

3.1.2 Mid-IR FP laser characterization

To evaluate the material quality before fabricating the DM lasers, broad area and FP lasers with varying cavity length were fabricated and characterised on the four wafers, only the results from the 2 μm wafer are presented in this section. As-cleaved broad area lasers with 50 μm wide ridge widths and varying cavity lengths were analysed under pulsed conditions (1 μs pulses with 0.1% duty cycle) to evaluate the material quality. The threshold current density (Jth) for the 1000 μm cavity length was 358 A/cm2 (∼119 A/cm2/QW) indicating good material quality. The slope efficiency variation with cavity length allowed the internal quantum efficiency (ni) and the internal optical loss (ni) to be estimated to be 80% and 8 cm−1respectively.

A 600 μm long FP ridge waveguide laser was packaged in a fiberised 14-pin butterfly module which contained a thermoelectric cooler and thermistor and the optical characteristics were measured under CW conditions. Figure 12 shows the overlapped CW measurement of light-current (LI) characteristics measured at chip temperatures 10, 25, 45, 50, 60 and 70°C. The power was measured with a large area (Ø3 mm) extended wavelength InGaAs detector (GPD 3000). The light coupling efficiency into the fibre was measured to be 60% and the chip ex-facet power was >20 mW at 200 mA, 25°C. The extracted threshold currents were 18, 30 and 58 mA at 25, 50 and 70°C respectively. The characteristic temperature of threshold current between 25–50 and 25–70°C was calculated to be 49 and 38 K. The measured slope efficiencies in the fibre at 25 and 50°C were 0.08 and 0.06 W/A respectively [3].

Figure 12.

Overlapped light-current curves in the temperature range 10–70°C for the 2 μm FP laser.

In Figure 13 the emission spectrum is plotted at a heat sink temperature of 25°C and bias current of 80 mA using a Yokogawa (AQ6375) long wavelength optical spectrum analyser. In Figure 14 we overlap the measured optical spectra over a temperature range from 15 to 50°C, the centre lasing wavelength shows a linear dependence with temperature with a tuning rate Δλ/ΔT of ∼0.83 nm/oC, which is consistent with that expected due to the temperature-induced change in the refractive index.

 

Figure 13.
Emission spectrum at a bias current of 80 mA and heat sink temperature of 25°C.

Figure 14.

Overlapped emission spectra at a bias current of 80 mA in the temperature range 25–50°C.

To demonstrate the wide wavelength coverage from 1.65 to 2.15 μm ∼400 nm we overlap the FP emission spectrum for the four wafers as shown in Figure 15.

Figure 15.

Overlapped FP emission spectra at bias currents of 80 mA and heat sink temperature of 25°C for the four InP wafers.

3.2 Design of DM laser diodes

Single wavelength operation in DM laser diodes is achieved by introducing index perturbations in the form of shallow-etched features, or slots, positioned at a number of sites distributed along the ridge waveguide as shown in Figure 16a [272829303132]. The slots are realized using ICP dry etching, with a typical depth in the region of 1.5–2 μm and a width of ∼1 μm. The slots are relatively shallow and are not etched into the active (wave guiding) region, however, they will still interact with the mode’s electric field as the mode profile is not fully confined to the active region and will expand into the surrounding cladding regions. This interaction results in a proportion of the propagating light being reflected at the boundaries between the perturbed and the unperturbed sections. In effect the slots act as reflection centres and through suitable positioning the slots manipulate the mirror loss spectrum of an FP laser so that the mirror loss of a specified mode is reduced below that of the other cavity modes [272829303132]. Using a simplified model, developed in [3334], a slot can be described as a one dimensional discontinuity inserted into the cavity; as most of the reflection comes from the front of the slot interface. Figure 16b shows a schematic of a laser cavity with slots introduced into the cavity; where rs is the slot reflectivity, ts is the slot transmission, N is the number of slots, L is the distance between the slots, and ϒi is the reflectivity in a section of the cavity where i is the slot number. The reflectivity from the first slot, ϒ1 is given by rs. The introduction of a slot into the waveguide changes its effective refractive index, so that it differs slightly from the segments of the waveguide without slots. The reflectivity from the waveguide to slot interface can be approximated using Eq. (1):

Figure 16.

(a) SEM image of 2 μm wide ridge waveguide with etched grating. The slot width is 1 μm and the spacing between the slots L is 4 μm in this example. (b) Illustration of slot reflection and transmission for N slots.

r s ≈ abs n 2 − n 1 n 2 + n 1 E1

where n1 is the effective refractive index of the waveguide and n2 is the effective refractive index of the waveguide with a slot.

Assuming no loss from the slot Eq. (2),

t s = 1 − r s E2

ϒ2 is the reflectivity from the second slot and is given by Eq. (3)

ϒ 2 = r s t s 2 exp − 2 iβL E3

where β is the complex propagation constant, and the term ts is squared to take account of forward and backward travelling waves. The exponential term describes the medium in which the light travels, and a factor of two is used again to take account of forward and backward travelling waves. The complex propagation constant takes account of the gain and loss in the transmission medium and is defined in terms of Eq. (4)

β = β re + iβ i = 2 πn λ + i g − α i 2 E4

where n is the refractive index, λ is the wavelength, is the optical gain and αi is the internal cavity loss. The reflectivities of the third and fourth slots are given by Eq. (5):

ϒ 3 = r s t s 4 exp − 4 iβL E5

and Eq. (6),

ϒ 4 = r s t s 6 exp − 6 iβL E6

respectively; therefore, the reflectivity obtained from four slots is given by Eq. (7):

ϒ total = ϒ 1 + ϒ 2 + ϒ 3 + ϒ 4
= r s + r s t s 2 exp − 2iβL + r s t s 4 exp − 4iβL + r s t s 6 exp − 6iβL E7

By letting Eq. (8)

X = t s 2 exp − 2 iβL E8

the total reflectivity from N slots can be expressed by Eq. (9) the following series.

ϒ total = r s 1 + X + X 2 + X 3 + . . … . + X N − 1 E9

Which in terms of known variables can be described as Eq. (10)

ϒ total = r s 1 − t s 2 exp − 2 iβL N 1 − t s 2 exp − 2 iβL E10

The power reflection is related to the reflection amplitude by Eq. (11),

R = abs ϒ total 2 E11

Using this model the power reflection versus etched feature number at a wavelength of 1887 nm was simulated and shown in Figure 17.

Figure 17.

Simulated power reflection spectrum as a function of slot number.

For a 600 μm long laser cavity at about 60 slots the peak reflectivity begins to saturate and the FWHM is about 0.9 nm which is equivalent to the FP mode spacing. So this is the optimum number of slots for this cavity length.

3.2.1 DM laser fabrication

The fabrication of the DM laser is exactly the same as the FP laser outlined in Section 3.1.2 width the addition of one extra dry etching step to etch the grating, the dry etch chemistry used again was Cl/N2 and was followed by a short wet-etch to remove surface roughness from the grating. A schematic of the etched features is shown in Figure 18.

Figure 18.

Schematic view of the InP DM laser.

3.2.2 DM laser diodes emitting at 1.87 μm

Low cost single mode semiconductor laser diodes emitting at 1.87 μm are highly desirable as light sources for trace gas sensing of H2O. The measurement of H2O is important in many industrial applications, for example, continuous emission monitoring in combustion processes where the vapour concentration can be related to performance parameters, such as, efficiency of combustion and heat release. In this section we present data on DM laser diodes operating around λ = 1.877 μm. Fabricated DM lasers exhibit continuous wave (CW) mode hop free operation in the temperature range from 15 to 55°C with emission wavelengths centred at 1.87 μm at 25°C, and ex-facet optical output power >3 mW at 25°C.

A ridge waveguide 600 μm in length DM laser diode was die bonded to an aluminium nitride submount and the optical characteristics were measured under CW conditions. Figure 19 plots the overlapped CW measurement of ex-facet LI characteristics measured at chip temperatures of 15, 25, 35, 45 and 55°C, with the same power and wavelength measurement setup as mentioned in the previous section. The extracted threshold currents were 12, 15, 18, 22 and 29 mA at 15, 25, 35, 45 and 55°C, respectively. The measured slope efficiencies at 15 and 55°C were 0.038 and 0.022 W/A, respectively.

Figure 19.

Overlapped CW LI curves as a function of heat sink temperature.

In Figure 20 the emission spectrum of the DM laser diode is measured at a heat sink temperature of 25°C and bias current of 100 mA. A peak wavelength of 1877 nm is demonstrated, with a side mode suppression ratio (SMSR) of ∼45 dB achieved, in excellent agreement with simulated values. In Figure 21a we plot the peak wavelength versus bias current as a function of laser submount temperature. The peak wavelength tunes linearly with bias current at a tuning rate of ∼0.017 nm/mA. In Figure 21b the optical emission spectrum over a wide temperature range, from −5 to 55°C, is plotted. The single mode peak lasing wavelength shows a linear dependence with current and temperature, with a tuning rate of Δλ/ΔI ∼0.017 nm/mA and Δλ/ΔT of 0.113 nm/oC, consistent with that expected due to the temperature-induced change in the refractive index [29].

Figure 20.

Normalised optical emission spectrum at a bias current of 100 mA and heat sink temperature of 25°C with SMSR >45 dB demonstrated.

Figure 21.

(a) Peak wavelength versus bias current over temperature. (b) Overlapped optical emission spectra versus heat sink temperature at a fixed laser bias current of 100 mA.

Wide gain bandwidth is demonstrated in Figure 22 where the DM peak wavelength is varied by changing the grating period wavelength tunability of 120 nm is achieved. This makes this material promising for widely-tunable mid-infrared single-mode devices such as DM arrays, external cavity lasers and sampled gratings. Eblana’s DM technology has been used to demonstrate single frequency lasers with high side mode suppression ratios spanning a wide wavelength range from 1.75 to 2.1 μm by using the appropriate InGaAs quantum well composition and thicknesses as shown in Figure 23.

Figure 22.

Overlapped single frequency spectra of 10 different DM lasers demonstrating 120 nm wide gain for the 1.8 μm wafer.

The wavelength and tuning results demonstrated by DM lasers in this chapter show that the devices operate at a single wavelength with SMSR >40 dB robustly over current and temperature variations and, furthermore, that these devices are highly suitable as low cost sources for TDLAS and other sensor applications. A further important feature of the DM laser diode is that its fabrication is far less complex than that of a distributed feedback laser diode resulting in a significant cost advantage.

4. Conclusion
In this chapter an overview in the current state of the art in mid-IR single mode lasers was presented and a low cost laser technology platform based on the InP material system for the manufacture of single mode laser diodes in the near to mid-IR wavelength range introduced. These DM lasers, are ridge waveguide Fabry Perot lasers whose emission spectra have been modified to produce a single mode operation. This modification is achieved during wafer processing by etching surface features into the ridge of an otherwise conventional ridge waveguide laser diode structure and therefore avoiding the need for grating overgrowth [35].

The basic principles underlying DM laser operation and their fabrication have been described. Basic static characteristics of the devices have been discussed and operation in the 1.6–2.1 μm spectral window demonstrated. The results demonstrate that InP-based light sources provide a promising concept for mid-infrared semiconductor diode lasers and are suitable for a range of sensor and other applications.

InP based diode lasers covering the 1.8–2.1 μm range have already reached a considerable level of maturity, as evidenced by the low threshold currents and good spectral performance as highlighted in Section 3. Thus current R&D focuses on the optimization of these lasers towards longer wavelengths >2.3 μm where specific application are in high demand.

Acknowledgments
This work was supported in part by the European project MODEGAP (FP/2007-2013 under grant agreement 258033) and by the European Space Agency (ESA) under contract reference ESTEC/ITT AO/1 7204/12/NL/NA.
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GT1 Laser Power Supply Product Instruction

GT1 Laser Power Supply Product Instruction

GT1+11Aisa type of laser-driven power supply composed ofone-channel small constant current driver, a two-channel TEC temperature control and system monitoring functions. The product uses a high-speed closed-loop constant LD driver, MCU central control and intelligent PWM thermostat control system to provide efficient and reliable temperature control for the driver and LD laser, suitable for driving a variety of low-power air-cooled solid-state lasers or laser module.

Feature:

1 channel efficient, high-speed constant-current drive LD.

1 channel PWM bi-TEC driver, heating and cooling.

Accurate PID temperature control

Internal / external control multiple mode selection.

Laser head type with automatic recognition.

Overheating, overcurrent, overvoltage, soft start multiple protection.

User interface is simple and easy to operate.

Small size, light weight.

LD maximum drive current : 2A ~ 11A (laser head automatic identification)

LD voltage: 2V adaptive

Modulation: Continuous / analog (external control) / Digital (external control)

The maximum modulation rate : 15kHz(Square wave)

TEC Temperature Range : 16.0~28.0℃

TEC maximum drive voltage: 11V

TEC maximum drive current: 5A

Rated voltage: 90~240V AC

Operating ambient temperature: -10~45℃

Dimensions (L × W × H) : 128mm×144mm×81mm

Total weight :  2.5kg

GT1 Laser Power Supply Product Instruction

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Global Laser Weapons Market Analysis and Trends Forecast to 2025

The research study presented here is a brilliant compilation of different types of analysis of critical aspects of the global Laser Weapons market. It sheds light on how the global Laser Weapons market is expected to grow during the course of the forecast period. With SWOT analysis and Porter’s Five Forces analysis, it gives a deep explanation of the strengths and weaknesses of the global Laser Weapons market and different players operating therein. The authors of the report have also provided qualitative and quantitative analyses of several microeconomic and macroeconomic factors impacting the global Laser Weapons market. In addition, the research study helps to understand the changes in the industry supply chain, manufacturing process and cost, sales scenarios, and dynamics of the global Laser Weapons market.

 

 

https://www.qyresearch.com/settlement/pre/d0cbdce7f5e2b516c3b13f8a6668c9e0,0,1,Global%20Laser%20Weapons%20Industry%20Analysis%20and%20Trends%20Forecast%20to%202025

 

Each player studied in the report is profiled while taking into account its production, market value, sales, gross margin, market share, recent developments, and marketing and business strategies. Besides giving a broad study of the drivers, restraints, trends, and opportunities of the global Laser Weapons market, the report offers an individual, detailed analysis of important regions such as North America, Europe, and Asia Pacific. Furthermore, important segments of the global Laser Weapons market are studied in great detail with key focus on their market share, CAGR, and other vital factors.

The report provides profiles of leading players operating in the global Laser Weapons market such as : Lockheed Martin Corporation, Northrop Grumman Corporation, Raytheon Company, Boeing Company, BAE Systems, Textron, Rheinmetall Ag, L-3 Communications Holdings, Moog, Quinetiq Group, Thales, Kratos Defense & Security

Type Segments : Fiber Laser Weapon, Gas Laser Weapon, Solid-State Laser Weapon, Semiconductor Laser Weapon

Application Segments: Defense, War, Homeland Security, Other

Regional Segments:

The chapter on regional segmentation details the regional aspects of the global Laser Weapons market. This chapter explains the regulatory framework that is likely to impact the overall market. It highlights the political scenario in the market and the anticipates its influence on the global Laser Weapons market.

Regions Covered in the Global Laser Weapons Market:

The Middle East and Africa (GCC Countries and Egypt)
North America (the United States, Mexico, and Canada)
South America (Brazil etc.)
Europe (Turkey, Germany, Russia UK, Italy, France, etc.)
Asia-Pacific (Vietnam, China, Malaysia, Japan, Philippines, Korea, Thailand, India, Indonesia, and Australia)

Table of Contents

Industry Overview: The first section of the research study touches on an overview of the global Laser Weapons market, market status and outlook, and product scope. Additionally, it provides highlights of key segments of the global Laser Weapons market, i.e. regional, type, and application segments.

Competition Analysis: Here, the report brings to light important mergers and acquisitions, business expansions, product or service differences, market concentration rate, the competitive status of the global Laser Weapons market, and market size by player.

Company Profiles and Key Data: This section deals with the company profiling of leading players of the global Laser Weapons market on the basis of revenue, products, business, and other factors mentioned earlier.

Market Size by Type and Application: Besides offering a deep analysis of the size of the global Laser Weapons market by type and application, this section provides a study on top end users or consumers and potential applications.

North America Market: Here, the report explains the changes in the market size of North America by application and player.

Europe Market: This section of the report shows how the size of the Europe market will change in the next few years.

China Market: It gives analysis of the China market and its size for all the years of the forecast period.

Rest of Asia Pacific Market: The Rest of Asia Pacific market is analyzed in quite some detail here on the basis of application and player.

Central and South America Market: The report explains the changes in the size of the Central and South America market by player and application.

MEA Market: This section shows how the size of the MEA market will change during the course of the forecast period.

Market Dynamics: Here, the report deals with the drivers, restraints, challenges, trends, and opportunities of the global Laser Weapons market. This section also includes the Porter’s Five Forces analysis.

Research Findings and Conclusion: It gives powerful recommendations for new as well as established players for securing a position of strength in the global Laser Weapons market.

Methodology and Data Source: This section includes the authors list, a disclaimer, research approach, and data sources.

Key Questions Answered

What will be the size and CAGR of the global Laser Weapons market in the next five

 

 

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Weld Quality Assessment in Fiber Laser Weldments of Ti-6Al-4V Alloy

Laser welding experiments are performed on Ti-6Al-4V alloy sheets by adopting fiber laser. A special kind of workpiece fixture is designed and fabricated for providing shielding gas. After experiments, penetration depth, fusion zone width and heat-affected zone size at different locations within weld bead are measured and discussed in detail. Influence of line energies on the formation of non-uniform microstructure within weld bead is explored by conducting microstructural analysis. Various kinds of microstructural morphology of martensitic structure such as α′ martensite, blocky α, massive α and basket-weave microstructure are found in fusion zone. Experimentally, it is found that beam power is the key parameter for controlling penetration depth. Higher hardness is noticed within fusion zone due to the existence of large volume of α′ martensite. Tensile strength and hardness of welded specimens are increased with decreasing line energy. Small amount of micropores are also found in solidified weld bead. However, its sizes are in acceptable range as per BSEN:4678 standard. Most favorable welding condition is identified as a combination of beam power of 800 W and welding speed of 1000 mm/min which yields full penetration, narrower bead width, small heat-affected zone, minimal defects and acceptable mechanical properties.

 

 

https://link.springer.com/article/10.1007/s11665-019-04073-4

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NIST Study Will Help Industry Understand and Use Laser Welding

GAITHERSBURG, Md., May 2, 2019 — A better understanding of the interaction between laser and metal could give industry more control over laser welding, according to a three-year study in laser welding conducted by the National Institute of Standards and Technology (NIST). The data that NIST scientists collected is being used by computer modelers to improve simulations of laser welding processes, a step toward applying the results of the study to industry.

The goal of the NIST team is to build a firm foundation for a model for laser welding that will help manufacturers determine which combination of laser settings will produce the best weld for their application. The NIST researchers are measuring everything that a simulator will need to model the outcome of a weld — the amount of power that is hitting the metal, the amount of energy the metal is absorbing, and the amount of material that is evaporating from the metal as it is heated — all in real time.

Inside NIST’s laser welding booth, a high-power laser melts a piece of metal to form the letters “NIST.” Courtesy of Paul Williams/NIST.

“Our results are now mature enough to where academic researchers are starting to use our data to thoroughly test their computer models in a way that they just haven’t been able to do before, because this kind of data hasn’t been available,” said physicist Brian Simonds.

Many of the techniques the researchers are using to collect the data were created at NIST to measure novel aspects of welding. To gauge laser power during a weld, the researchers designed and built a device that uses the pressure of the laser light to measure the power of the laser. To sense the amount of light absorbed by the heated material as it undergoes changes, they surrounded the metal sample with a device called an integrating sphere, which was designed to capture all the light bouncing off the metal. Using this technique, the researchers discovered that the traditional method for making this measurement underestimates the amount of energy absorbed by the metal during a laser weld. The integrating sphere also allowed the data to be measured in real time.

The team also devised a way to measure the weld plume using laser-induced fluorescence (LIF) spectroscopy. To detect the tiny amounts of elements that evaporate out of the sample during welding, the researchers hit the plume with a second laser that targeted one kind of element at a time. The targeted element absorbed the second laser’s energy and then released it at a slightly shifted energy, producing a strong signal that is also a unique marker of that element. So far, the researchers have demonstrated that LIF can sense trace elements in the weld plume with 40,000× more sensitivity than traditional methods.

All of the experiments are being conducted with a type of stainless steel that is a NIST standard reference material. Use of a standard reference material ensures that experiments conducted anywhere in the world will have access to metal samples with a composition identical to those used by the NIST team.

The NIST researchers said that a multikilowatt laser beam can heat a smaller area of the metals being joined, creating a smaller, smoother seam than a conventional weld, and that laser welding is faster and more energy-efficient than conventional welding. Even with these and other advantages, laser welding makes up only a small fraction of overall welding efforts in the U.S. that could benefit from this technique. A better understanding of the process could make it easier for industries to consider investing in laser-welding infrastructure, the researchers said.

The NIST scientists are collaborating with institutes around the world to expand the data set. They will collaborate with the U.S. Department of Energy’s Argonne National Laboratory to take advantage of that lab’s ability to do high-speed x-ray imaging of the molten pool of metal in real time. Other collaborators include Graz University of Technology, Queen’s University, and the University of Utah.

The researchers are also broadening the scope of their work by directing their high-power laser beams onto metal powders. The powder studies could directly support the community of additive manufacturing, a market worth more than an estimated $7.3 billion in 2017.

The research was published in Applied Optics, a publication of OSA, The Optical Society (https://doi.org/10.1364/AO.58.001239); in Physical Review Applied (https://doi.org/10.1103/PhysRevApplied.10.044061); and in Procedia CIRP (https://doi.org/10.1016/j.procir.2018.08.072).

To learn more about laser welding, register for a free Photonics Media webinar, Laser Source Selection for Microwelding Applications, on June 25, 2019, 1 to 2 p.m. EDT.

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Navy to Develop Laser that can Destroy Small Boats

Navy to Develop Laser that can Destroy Small Boats

The U.S. Navy is developing a laser weapon system that can destroy small boats and hostile drones, as well as provide long-range counterintelligence and surveillance. The first system is scheduled to be installed on a guided missile destroyer sometime in 2020

The United States Navy is moving forward with a new laser weapon system that can “disable” or “destroy” small boats or hostile drones. Lockheed Martin is responsible for developing a system that can strike multiple targets at the speed of light in an ever-changing world of warfare.

The Department of Defense has awarded Lockheed Martin a $150 million contract to develop different types of laser systems that will be installed and tested on the guided-missile destroyer Arleigh Burke (DDG-51), which is the lead ship in a class of 60 destroyers.

The laser system is called a High Energy Laser and Integrated Optical-dazzler with Surveillance (HELIOS) system, which will be fixed on surface ships. Lockheed Martin vice president Michele Evans, the general manager of the company’s Integrated Warfare Systems and Sensors, said this one-of-a-kind weapon helps add another layer to the Navy’s defense capabilities.

“The HELIOS program is the first of its kind, and brings together laser weapon, long-range ISR and counter-UAS capabilities, dramatically increasing the situational awareness and layered defense options available to the U.S. Navy,” Evans said in a statement. “This is a true system of capabilities, and we’re honored the Navy trusted Lockheed Martin to be a part of fielding these robust systems to the fleet.”

The laser system will actually combine different capabilities, from destroying attack boats to conducting long-range surveillance and counterintelligence, according to Lockheed Martin’s website.

One part is a high-energy laser system that can knock out hostile drones or small boats, with the ability to disable or destroy them, using 60-150 kilowatts of steady power, according to IEEE Technology. Second, there is long-range capability for intelligence, surveillance and reconnaissance (ISR). A third portion of the weapon will be designed to counter unmanned aerial systems. This includes using sensors to confuse cameras and other optics on unmanned drones and other flying objects.

Once the Laser Weapons System (LaWS) is developed and installed on the Arleigh Burke by 2020, there will be multi-layered testing of the system, from cooling, maintenance, how much of the ship’s power it would take and how it would integrate with the rest of the ship’s weapons, whether it’s guided missiles or the Close-In Weapon System (CIWS) also known as the Phalanx — or the R2D2 to those in the fleet.

The LaWS on the Arleigh Burke is scheduled for battle testing by 2021, according to the U.S. Naval Institute.

Rear Adm. Ron Boxall said it’s imperative for the Navy to move forward with LaWS to continue leading the world in cutting-edge warfare.

“We are going to burn the boats if you will and move forward with this technology,” Boxall said in the Naval Institute report. “The problem I have today is the integration of that system into my existing combat system. If I’m going to burn the boats, I’m going to replace something I have today with that system doing that mission with these weapons. If I have this system that can kill and I have a system that can actually sense, then I have to make sure it integrates with the other things I have on my ship that can sense and kill, namely the Aegis weapon system.”

Boxall called it a “crawl, walk, run approach,” meaning to start on a simplistic level and working its way up to more sophisticated laser warfare defense.

This isn’t the Navy’s first foray into using laser systems aboard a surface ship. In 2014, the Navy implemented a 20-kilowatt system on the USS Ponce, a former amphibious port dock ship that has since been decommissioned. That system was designed to deter small boats and drones.

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Homemade Laser Maze

Here we will make a homemade laser maze.  The old laser maze use several laser beam producers, and they also need a special room for lasers, like the following laser maze.

We need a laser module + several mirrors + a light sensor to make a laser maze.

The laser module is Square shape long working 5V DC powered green laser, that means it can be working for several hours. We recommend low power laser for beginners , such as 100mW.

You need a green safety goggles while working on this project.

1) Think about the beam network, that how you want the laser beam goes through the room.

2) Fix the laser module, you need to fix it tightly, as if the laser moves, the laser beam will move.

3) Fix the mirrors through the laser beams step by step.

4) Fix the light sensor at the end of the laser beam