This PDF file contains the front matter associated with SPIE Proceedings Volume 11262 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

We developed a 1kW cw fiber-coupled diode laser at 9XX nm by using beam combining of eight high power diode laser bars. To achieve beam combining, we employ Lyot-filtered optical reinjection from an external cavity, which forces lasing of the individual diode laser bars on intertwined frequency combs with overlapping envelopes and enables a high optical coupling efficiency. Unlike other spectral beam combining techniques that are based on the use of grating elements, this technique is insensitive to the thermal drift of the laser diodes. In addition to this, the FWHM spectral width at 1 kW output power is only around 7 nm, which is convenient for wavelength sensitive applications such as pumping.

We report the highest power conversion efficiency (PCE) of 74.6% at peak and more than 70% PCE maintained up to high output power of 20W in broad stripe laser diodes (LDs) lasing at a 9xx-nm band. Optimal layer structure design including enhancement of asymmetry in waveguide structure and elimination of nonlinear resistance due to band discontinuity enables electric resistance to be reduced by 33% compared to conventional LDs without notable increase in optical internal loss. These PCE values from middle to high output power range marks the highest record reported so far.

Mid-infrared (MIR) solid state lasers based on thulium and holmium-doped crystals are of increasing interest in applications in medicine, material processing and particle physics. Thulium-doped lasers can be efficiently pumped at wavelengths around 780 nm and diode laser pumps with high conversion efficiency and high intensity are sought at this wavelength. Diode lasers integrated in laser stacks suitable for high duty cycle pumping are of particular interest for high energy class applications, especially when realizable without need for the additional cost and reliability hazard of microchannel cooling. However, high efficiency and reliable power is more challenging to realize at 780 nm than around 940…980 nm, due to limitations on the capability of the available semiconductor materials. Progress is therefore presented here in the design, realization and test of 780 nm pump sources suitable for high energy class pump applications, using GaAs-based TM-polarized diode lasers. We show how power per device can be increased from 4 W for conventional single emitters (90…100 μm) up to 60 W at high duty cycle (10%) and long pulse length (10 ms) for high brightness large aperture emitters (with 1200 μm aperture, equivalent to around 500 W per bar), at the cost of reduced operating efficiency (from 60 to 50%). We show progress in integrating these large aperture emitters into novel passively (macro-channel) edge-cooled stacks, that are then suitable for use in pumping high energy class Th:YAG laser systems.

We present 1 kW-emitting diode-laser bars optimized for higher conversion efficiency and smaller far-field angle Θ_95% power content), as needed, e.g., for solid-state laser pumping (wavelength λ= 940 nm). First, we review the latest high-efficiency designs, targeting reduced series resistance R_s and less power saturation and then discuss developments for high brightness via tailored chip-internal heat distribution. Recent results include conversion efficiency η of 66% and far-field width Θ _95%= 8.8° at 1 kW (thermal resistance R_th ~ 0.02 K/W), as well as 64% efficiency and 10.8° divergence at R_th ~ 0.05 K/W, equivalent to CW operation with advanced packaging.

The industrial laser market has rapidly expanded over the past decade with the emergence of advanced high brightness solid state laser technology. Thin disk laser systems are important examples of these powerful tools enabling a range of high-end CW materials processing applications such as 2D sheet metal cutting and remote welding applications, and the rising demand for a range of demanding high-energy pulsed applications of high average power. Commercial applications with power in the range of 8 kW- 20 kW can be cost competitive using disk lasers in moderate volumes compared to more commoditized solid-state laser sources such as fiber lasers.

Reduction in the cost structure of disk laser pump sources requires an increase in brightness, efficiency and power of diode lasers bars within. Here we show the development of thin disk laser pump modules from an original common cooler platform with ~180 W per laser bar to recently developed individually cooled laser bars each operating continuously over 300 W. We demonstrate pump modules utilizing these bars with total power of up to 2.4 kW at 940 nm. Cooling in such laser modules is provided by mounting laser bars on isolated laser coolers (ILASCO). The ILASCO cooler comprises a multi-layer structure of aluminum nitride and copper sheets that are designed to decouple the direct current path from the water cooling eliminate electro-corrosion and to maximize heat dissipation and match the thermal expansion of the diode laser bar.

We demonstrate advances in the single quantum well InGaAs/AlGaAs laser epitaxy design and chip layout that enables high power operation at operating temperatures up to 80°C. We show increase in peak electro-optic efficiencies from 55% to over 60% at this temperature. With the application of advanced facet passivation technology, we demonstrate >35 khr reliable operation in the application through accelerated aging tests.

Both broad-area and single-mode strained InGaAs-AlGaAs single quantum well (QW) lasers are indispensable components for both terrestrial and space satellite communications systems due to their excellent power and efficiency characteristics. However, their degradation mode (catastrophic and sudden degradation) due to catastrophic optical damage (COD) is a major concern especially for space applications, since COD-prone lasers typically show no obvious precursor signature of failure. Furthermore, as our group first reported in 2009, these lasers predominantly degrade by a new failure mode (bulk failure) due to catastrophic optical bulk damage (COBD) unlike AlGaAs QW lasers that degrade by a well-known failure mode (facet failure) due to catastrophic optical mirror damage (COMD). Unlike COMD, there have been limited reports on root causes of COBD. In addition, none of decades-long studies of reliability and degradation processes in (Al)GaAs or InGaAs QW lasers by many groups have yielded a reliability model based on the physics of failure. As part of our efforts to develop a physics of failure-based reliability model of InGaAs-AlGaAs strained QW lasers, we continued our investigation by performing short-term and long-term lifetests, failure mode analyses, and root causes investigations using various destructive and non-destructive techniques. All of broad-area and single-mode lasers that we tested degraded by COBD. We employed electron beam induced current (EBIC) techniques to study formation of dark line defects (DLDs) of lasers stressed under different test conditions and time-resolved electroluminescence (TR-EL) techniques to study the dependence of DLD propagation on electrical-thermal stresses via recombination enhanced defect reaction. Also, we employed high-resolution TEM and deep level transient spectroscopy (DLTS) techniques to study extended defects and point defects (and electron traps), respectively. Finally, we report on reliability model parameters obtained from our physics of failure investigation and compare them with those extracted using an empirical model.

The 793nm semiconductor diode cladding pumped Thulium-doped high power fiber laser operates around eye safe 1.9 ~ 2μm and output power can reach to kW level. Those 2μm high power fiber lasers are attractive in various applications in industrial use, medical field, remote sensing and military use. High power, reliable 793nm diodes and cost-effective pump modules are the key component in enabling widespread use of Tm-doped 2μm fiber laser for commercial applications. The latest generation of Coherent AAA^TM epi design platform is optimized for low internal loss, high quantum efficiency and higher linear power density at 793nm region. Two types of high power diode lasers are tested; one is a single emitter with 100μm emission width and the other is a tailored bar (T-bar) including five 100μm emitters with 1mm pitch. The single emitter can achieve 5.6W output power at 5A with 1.26W/A slope efficiency and 60.3% E/O efficiency. Those single emitters are packaged and coupled into a 100μm fiber. At 5A current, a three single emitter based 100μm fiber-coupled module’s output power is 13.4W and the E/O efficiency is 48.0%. The T-bar can reach up to 30W output power at 30A with 1.19W/A slope efficiency and 56.4% peak E/O efficiency. Nine T-bars are mounted and coupled into a 225μm fiber-coupled module and 150W output power and 47.3% E/O efficiency are achieved at 19.1A current. Both single emitter based and T-bar based fiber-coupled modules show long reliable life; single emitters based module’s life is more than 20,000 h at 4A and T-bars based module’s life is more than 10,000 h at 20A.

Due to their short focal lengths, FAC lenses significantly influence the performance of high-power diode laser systems. In addition to the shape, coating and surface quality, high demands are placed on the assembly accuracy for these microoptical components. In order to optimally align and position the lenses despite varying properties (e.g. focal length), active alignment strategies are used. The automation of the active alignment process for production offers enormous potential. Compared to manual processes, the reproducibility and accuracy of the alignment is increased. For the automation of the active alignment process, a deep understanding of the system behaviour is necessary. To control a diversity of variants cost-effectively and robust, new approaches must be taken into account. Concepts of AI or machine learning are great for this kind of generalization and adoption and they have many advantages for the active alignment of systems like DOEs or free-form-optics, with a complex system behaviour. In this publication, we want to compare the performance of a classically model-based algorithm and a machine learning approach for the automated active alignment of FAC-lenses. The model-based algorithm uses a physical model of the metrology system (including the FAC to be aligned) to estimate a misalignment in 4-DOF. The machine learning algorithm consist of a deep neuronal network which was trained with image data.

In this paper, we show results of further brightness improvement and power-scaling enabled by both the rise in chip brightness/power and the increase in number of chips coupled into a given numerical aperture. We report a new chip technology using new extra Reduced-mode (x-REM) diode design providing a record ~363 W output from a 2×12 nLIGHT element® in 105 μm diameter fiber. There is also an increasing demand for low size, weight and power-consumption (SWaP) fiber-coupled diodes for compact High Energy Laser (HEL) systems for defense and industrial applications. Using thirty single emitters that were geometricallyand polarization-combined, we have demonstrated 600 watts and 62% efficiency at in 225 μm/0.22 NA fiber resulting in specific mass and volume of 0.44 kg/kW and of 0.5 cm³/W respectively. Furthermore, we have increased the number of chips to forty and increased the output power to 1kW and 52% in the same fiber diameter and numerical aperture. This results in a fiber-coupled package with specific mass and volume of <0.18 kg/kW and <0.27 cm³/W, respectively.

Active or sensor guided alignment presents a promising production approach for high-quality optical products and helps to overcome challenges in the tolerance chain. Application fields such as fast-axis collimation increasingly deploy automated productions solutions in order to improve and ensure stable quality even with relatively low production volume. The advantages are offset by the high demand towards the engineering as upfront cost, common to all automated production solutions with integrated evaluation of the system function. In this paper, we present our approach to overcome this problem. We propose the use of virtual environments, which are derived from empirical data generated with minimized effort in early phases of the product development. We will present options for building the necessary dataset and how our solution can derive an empirical simulation due to the application of artificial intelligence. Our solution is independent from ray tracing simulations and reflects defects, deviations and tolerances as observed in the actual product samples. This allows developing alignment algorithms offline, without the need for costly machine time and the risk of damage due to manual errors. We will present validation results, which demonstrates the capability to transfer active alignment algorithms from the virtual environment to actual automation equipment. Next to FAC alignment and the high-power laser industry our virtual environment solution is of special interest to application in the field of diffractive optical elements (DOE) and free-form optics, where low volume or changing designs demand adaptable automation solutions.

High power wavelength-stabilized 976nm diode lasers attract more attention recently with the development of higher power, higher efficiency and higher brightness fiber lasers. The wide spectrum of a high-power diode laser without wavelength stabilization (about 5 nm), together with thermal shift at about 0.3 nm/°C, strongly limits the conversion efficiency benefits at 976 pumping. In this paper, we will report the development of kilowatt wavelength-stabilized CW and QCW diode lasers at BWT.

We present an overview of autonomous driving with examples of real world problems. Core to this technology are lidar sensors. Lidar provides three dimensional maps with depth perception on targets with a range of reflectivity in a scene. Sensors need to provide high angular resolution, large field of view, and low latency. We review different lidar technologies and discuss the tradeoffs with laser performance. In particular, we discuss the implications on output power, short pulse operation, and etendue for high power semiconductor lasers.

We report on the development of high peak-power laser diodes emitting in the 1.5 µm wavelength band. Two design approaches, broad-area laser diodes and tapered laser diodes, are described, both with integrated wavelength locking using distributed Bragg reflector. The peak output power of the broad-area components and tapered components is 6.1 W and 4.6 W, respectively. The output spectra of both component types are narrow with less than 0.3 nm full width at half-maximum, and due to the grating the emission wavelength is resistant to drift caused by temperature changes.

Diode lasers providing nanosecond optical pulses with high peak optical powers are key components in systems for freespace communication, metrology, material processing, spectroscopy, and light detection and ranging (LIDAR) as employed for, e.g., autonomous driving. Here, we report on laser sources for line-scanning automotive LIDAR systems. The laser sources are implemented as distributed Bragg reflector diode lasers bars featuring 48 broad area emitters each with a 50 μm wide mesa structure. The epitaxial layer structure comprising an AlGaAs-based waveguide and InGaAs single quantum well is optimized for pulsed operation at a wavelength of around 905 nm. For a temperature-dependent wavelength shift as low as approx. 60 pm/K, each emitter features a surface-DBR grating. The DBR laser bars are mounted p-side down on CuW submounts and sandwiched between a thin electronic driver board and a mount to minimize inductances. The in-house developed electronic driver generates 2 ns to 10 ns long current pulses with peak current up to 1000 A. With 8 ns long optical pulses and a peak current of about 900 A, a peak optical power of about 640 W is achieved at 25°C. Integration of the diode laser with micro-lenses and a beam twister provides a homogeneous line by individual projection of each of the 48 emitters with divergence angles of 24 deg x 0.1 deg (full width at 1/e² intensity) in the vertical and horizontal direction, respectively.

The results of research and development of a pulse laser module are presented. The aim was to create and a compact pulse laser source with a peak power of more than 10 W for optical pulses of 10 ns - 10 μs duration, emitting in spectral range 900-1600 nm. Pulsed modules were based on MOCVD-grown edge-emitting multimode semiconductor lasers integrated with a pulse pumping board. It was shown that the laser output characteristics can be optimized via a series resistance in the laser pump circuit. The 1550 nm wavelength modules with free-space outputs showed power levels of 15 and 25 W, for 1 μs and 100 ns pulses respectively, at 25° C temperature with a regular pulse shape.

It is well documented that increases in pump module power enables higher power DPSS or CW fiber lasers, but it is important to recognize that increasing the efficiency by which the DPSS or CW fiber laser is pumped drives down both system complexity and cost. Additionally due to the narrow absorption band of the common laser mediums like Ytterbium and Neodymium, it is advantageous to maximize the spectral overlap between the emission of the pump module and the absorption band of the host medium; one way to accomplish this is by the use of Volume Bragg Gratings (VBGs) to both narrow and stabilize (meaning to minimize change with current and/or temperature) the emission of the diode pump module. To this end, we report on the continued progress by nLIGHT to develop and deliver the highest efficiency wavelength-stabilized, diode-laser pumps using single-emitter technology at ~885nm for neodymium DPSS pumping, and 969/976 nm for ytterbium laser pumping. The basis for these improvements is the ensuring the epitaxial structure of the laser diode is optimized not only for efficiency and power but is also properly optimized to minimize the amount of spectral shift with current. Due to the proprietary nature of our epitaxial structures, we are unable to provide exact details. However, throughout this paper, we will abstractly discuss the improvements made to our epitaxy, and how those changes directly affect, and improve upon the module level performance with VBGs, and provide COS and module level results for our element® packages with VBGs to support these claims, with key examples being: at 969/976 nm a 2×6 module with 140 W into 105 μm – 0.16 beam NA, and a 969/976 nm 400 W 2×12 into 200 μm – 0.16 beam NA, along with 888 nm diode module, in a 2×12 layout outputting a maximum of 370 W with 52 % electro-optical efficiency when coupled into 200 μm – 0.18 beam NA

This work presents a miniaturized laser module featuring an optical output power of more than 14Win continuous wave operation. Simultaneously, a beam quality factor of less than 2 is reached at the operating power. The laser module layout is based on the use of tapered diode lasers featuring wavelength stabilization by a monolithic distributed Bragg grating. Such a single laser source achieves a reliable output power in the order of 8W in continuous wave mode at a wavelength of 980nm [1]. To enhance the output power while maintaining the beam quality of the single emitters, two laser beams were combined by the use of polarization coupling. The use of custom designed beam couplers is necessary to combine the given radiation intensities. A thin film polarization optic, adapted to the output wavelength was used. All optical components where designed to be housed inside of a module with a footprint of 58 x 34mm². Due to the close spatial vicinity of the laser sources, thermal simulations were carried out to avoid thermal crosstalk and ensure stable laser operation. The modules high beam quality enables pumping of solid state lasers and amplifiers even without challenging optical pumping geometries.

This paper reports preliminary performances of a multiemitter diode laser module using ten spatially multiplexed Distributed Bragg Reflector - High Power Diode Laser (DBR-HPDL) chip, emitting 100 W CW in the 920 nm range, with 95 % of power in 0.17 N.A., on a 135 um core / 155 um cladding multimode fiber, and stabilized spectrum width of only 0.6 nm.

Diode chip implemented an integrated multiple-orders Electron Beam Lithography (EBL) optical confining grating, stabilizing on same wafer multiple wavelengths using a manufacturable, reliable and high yield technology. Up to three pitches, DBR-HPDLs 2.5 nm spaced have been demonstrated on same wafer with excellent uniformity of performances across the wafer and emitted wavelengths.

Since the absence of any wavelength locking optical element in the collimated beam path, multiemitter module of DBRHPDL was assembled and tested in the production line using standard assembly process flow and without requiring any special alignment, as maturity demonstration of the proposed technology for mass production of wavelength stabilized high-power laser modules.

High radiance red-emitting light sources are required for several laser applications such as holography, interferometry or various types of spectroscopy. As many of such applications are moving out of the lab into industrial environment there is a high demand for small sized, efficient and reliable laser sources, for which semiconductor lasers are preferred. We will present a red-emitting DBR tapered diode lasers near 633 nm which provide more than 250 mW of optical power. The coherence length is more than 1 m and the beam quality is almost diffraction limited with M²_1/e² = 1.2. We also demonstrate an operation of more than 10000 h at a power level of 200 mW to 250 mW, making these lasers an ideal replacement for high-power HeNe lasers.

Pure copper processing is widely demanded in automobile, aerospace and electrical industries and so on since pure copper has excellent properties such as thermal and electrical conductivities. However, high quality welding and cladding of pure copper with near infrared lasers such as fiber, disk and diode lasers have not been performed yet. Their absorption rates of them for pure copper were less than 10 %. Therefore, we focused on blue (450 nm) diode laser with its absorption rate for pure copper of about 60 %. In this paper, we reported development of high power blue diode lasers for welding and additive manufacturing including cladding.

Recent product releases of high power direct diode lasers in the blue spectral range of up to 1 kW of output power have sparked the demand for even higher optical output power for industrial copper welding applications, in particular related to e-mobility demands where high throughput is required. Blue laser bars maturing into a reliable technology present the ideal laser source for the task. While previously presented results of up to 500 W of output power from a 200μm NA 0.2 fiber were based on the Coherent ‘High Brightness’ product platform, the current work uses the ‘High Power’ product line, currently available with up to 8 kW of output power in the near infrared spectral range. This platform has the potential of reaching up to 4 kW of blue laser power from fibers with core diameters between 400μm and 800μm at wavelengths near 450nm. An increased number of laser bars compared to the existing product portfolio can achieve even higher output power. While the ‘High Brightness’ platform is based on mini-bars with 5mm length and designed for coupling into 200 μm core fibers, the ‘High Power’ product line uses 10mm wide laser bars. The focus lies on 400 μm core fibers in order to achieve high intensities at the work piece while maintaining a long working distance. However, for very high output power 600 μm and 800 μm fibers will be used. Here we present first results of the smallest laser module within the high power family with a goal of coupling 1500 W of optical power into a 400 μm NA0.22 fiber at an emission wavelength of approximately 450 nm. The product architecture and optical concept are described. Latest results showing 1.5 kW from a 600 μm core fiber at 5% duty cycle are presented and the next steps to reaching the goals of CW operation and 400 μm core size are discussed.

Blue laser diodes are emerging as the next revolution in laser material processing, especially for high reflective materials, such as copper and gold. The paper presents the most recent evolution of a family of medium-high power and high brightness devices specifically conceived for micro-machining applications. The modules make use of a proprietary architecture based on the combination of commercial laser diodes in TO9 package. The diodes are first organized in rows staggered along the fast axis, then the rows are multiplexed along the fast axis; finally, wavelength and polarization multiplexing are exploited to achieve up to 100W of power into a 50 μm/0.22NA fiber.

This paper presents the results of welding tests performed with a 1kW blue laser to determine the power and spot characteristics necessary to be able to perform all the welds required in a battery and battery pack. The results of this study indicate that a minimum of 1,500 Watts with a nominal beam parameter product of 11 mm-mrad is required to interface with a scanner and achieve all of the welds required by this application. Several other key industrial applications are discussed, and the welding performance is characterized for various materials. These results are used to define the optimum laser system parameters to serve a broad range of applications. A new blue laser product architecture is presented that is capable of scaling to multi-kW power levels in order to meet the target performance. The building block for this architecture is a 400-Watt blue laser module. These units can be combined to produce systems of any power level in 400- Watt increments with excellent beam quality. The 1,500-Watt product being developed has a beam parameter product of less than 17 mm-mrad.

Blue high-power semiconductor lasers have increased greatly in performance over the recent decade enabling new application fields from high brightness projection up to materials processing beyond 1000W output power systems. Base for best system performance is optimal chip design and reliability of the semiconductor device. In this paper chip design optimization of blue high-power semiconductor laser bars will be shown: In contrast to IR laser bars with high lateral emitter fill factors beyond 50%, optimum design with maximum output power and efficiency for GaN laser bars is currently at very low fill factors in the range of 10%. Laser bar designs ranging from 5% fill factor up to 12.5% fill factor were fabricated and investigated. Additionally, two different emitter pitches with 200μm and 400μm were compared. The design with an emitter width of 30μm and a pitch of 400μm resulted in overall best performance. Additionally, lifetime investigations of single emitters in TO-packages will be discussed. The laser diodes were tested up to 5000h duration at different conditions in operating temperatures ranging from 64°C to 96°C and output power up to 3.5W. Dominating degradation mechanism is wear-out which is accelerated by optical output power and additional thermal activation. Extrapolation of the test results in combination with an acceleration model points towards a median lifetime of up to 65.000h for 25°C operation.

The unique growth conditions of BluGlass’ low growth temperature technology Remote Plasma Chemical Vapour Deposition (RPCVD) are capable of producing Activate As-Grown (AAG) buried p-GaN layers. This ability renders RPCVD a highly attractive technique to produce GaN-based Tunnel Junctions (TJ) without the complexities associated with the post-growth lateral activation steps required by MOCVD. In this paper we discuss the use of hybrid RPCVD/MOCVD TJs for MOCVD-grown ridge guide laser diode (LD) applications. The impact of both the structure and placement of the TJ on the total optical loss of the LD are investigated. TJs conforming to the strict compositional requirements in order to yield a net reduction in optical loss are demonstrated, paving the way to improved conversion efficiencies through the replacement of the highly resistive p-AlGaN cladding layers and p-type Ohmic contacts with lower resistance n-AlGaN cladding layers and n-type Ohmic contacts.

A smile-suppressed high-power InGaN laser array has been developed for a high beam quality material processing light source. The smile effect becomes apparent especially in InGaN laser array with large chip curvature due to lattice mismatch of epitaxial growth layers. To reduce the smile, periodic grooves are introduced to the epitaxial layers for removing the origin of strain. It also enables a two-dimensional strain management of remaining epitaxial layers. This technology improves the chip curvature within micron range, i.e. as small as 0.3 μm in a 9 mm-width InGaN laser array. We have successfully realized reducing the smile to 0.4 μm without degrading the laser light output characteristics.

Light sources in digital projection experience a transition from Xenon to laser pumped phosphor and pure RGB laser sources with constantly growing light flux. Today’s state of the art cinema projectors with laser sources are achieving a light flux of up to 75000 lumens to illuminate screens of 30 m diagonal and more. With increasing light flux the thermal load on the optical components increases, limiting the quality of the projection. The optical system of high-end cinema projectors usually consist of a large volume prism assembly and a high-end projection lens system. Especially the prism assembly experiences a high thermal load due to long light paths. The requirements on the performance of the optical glass in terms of maximum transmittance therefore constantly increases. Proper material characterization and selection helps to enable future projection requirements.

Laser phosphor projection sources enable a cost effective way to generate high light flux, since they take advantage of the recent cost down of blue laser diodes and do not need to use expensive green and red lasers. The primary colors are e.g. generated by blue laser diode illuminating a phosphor wheel to create yellow light. The yellow light is subsequently split into green and red light by means of e.g. a dichroic filter. With increasing light flux standard phosphor wheels that are based on a phosphor embedded in silicone, degrade at high peak temperatures. Wheels with a ceramic phosphor have a much higher temperature stability and offer a significant improvement. This paper discusses the requirements on optical materials used for digital projection.

Industrial High-Power/High-Brightness Direct Diode Laser (DDL) are rapidly evolving as one of the preferred laser technologies for metal processing with several benefits such as higher processing speeds, superior applications quality and wall plug efficiencies higher than 40%. This paper focuses on the recent advances applying Wavelength Beam Combining (WBC) technology to diode bars emitting in the 400nm region to demonstrate the power scalability with beam qualities only archivable using WBC technology. Also, will talk about the 6kW/100um laser in the 975nm region using the Fast-Beam-Shaper (FBS) capable of dynamically and continuously changing the shape of the beam in a couple of milliseconds to shape-modulate the output beam to closely match the application requirements. We will also show an approach for a 6kW/50um extended broadband laser in the 875-1000nm spectral region that doubles the brightness capabilities of DDL and enhance the metal processing quality.

The paper reports on the design and development of an innovative high power and high brightness laser diode module that is capable of delivering more than 350 W at 976 nm in a standard 0.2 NA 50/125 fiber and 95% of power is in 0.15 NA. This module combines Everbright's multi-emitter modules assembled with 50 μm ridge width 976 nm laser diode chips through dense wavelength beam combining (DWBC) and polarization combining. The intrinsic wavelength stabilization of DWBC technology allows the use of the module for efficiently pumping Yb-doped fiber lasers.

A family of laser diode modules emitting hundreds of watt and based on intrinsically wavelength stabilized narrow linewidth high-power Distributed Bragg Reflector (DBR) chips has been manufactured and fully characterized. The module layout exploits a proprietary architecture to combine through spatial and wavelength multiplexing several highly manufacturable chips that integrate a grating and therefore do not require additional external stabilization devices to allow dense wavelength multiplexing. Power levels going from 200W to 400W in a 135 micron core fiber have been achieved using two to four wavelengths. The narrow spectral emission of each chip makes the modules suitable not only for direct-diode material processing, but also for laser pumping.

NIR VCSELs are proliferating from Datacom to Consumer Electronics and Automotive Applications. 3D object detection and imaging at distances from 1 to 100m is in the focus. VCSEL arrays for Flash LiDARs are considered or already in use for in-cabin/exterior-to-car detection, ADAS, gesture recognition, drones, robotics etc. In this work, we propose high peak power NIR VCSEL arrays with large range of field of view (FOV). The effective refractive index (neff) of the core and clad sections of the VCSEL structure based on industrial standard III-V processing is adapted to these applications. Controlling the transverse lasing modes, beam divergences as large as 46° can be achieved. Using the symmetric radiation profile and wide FOV, segmented VCSEL arrays offer a wide range of object detection applications, needing in addition adapted driver ICs and angled diffusers.