Narrow versus broad waveguide laser diodes: a comparative analysis of self-heating and reliabilityDemir, Abdullah; Sünnetçioğlu, Ali Kaan; Ebadi, Kaveh; Liu, Yuxian; Tang, Song; Yang, Guowen
doi: 10.1117/12.3002971pmid: N/A
Semiconductor Laser Diodes (LDs) generate high output powers with high power conversion efficiencies. While broad-area LDs are favored for high-power applications, narrow-waveguide LDs are in demand for their single-mode characteristics. However, LDs suffer from device failures caused by Catastrophic Optical Damage (COD) due to elevated self-heating at high operating currents. It is critical to understand the COD mechanism in these devices to enhance their reliability and operating output power. In this study, we investigated the self-heating and temperature characteristics of LDs with varying waveguide widths to uncover the cause of their failure mechanism. We assessed the performance, junction, and facet temperatures of the narrow (W=7 m) and broad waveguide (W=100 m) LDs. The narrower waveguide LDs achieved and operated at higher output power densities but, surprisingly, maintained lower junction and facet temperatures. Additionally, we employed a thermal simulation model to analyze heat transport characteristics versus LD waveguide widths. The simulation results showed that narrower waveguide LDs exhibit improved three-dimensional heat dissipation, resulting in reduced junction and facet temperatures and, thus, enhanced reliability. Our simulations align well with the experimental data. The findings demonstrate a transition in heat dissipation characteristics from broad to narrow waveguide behavior at approximately 50 m width. These results clarify the fundamental reasons behind the superior reliability of narrower waveguide LDs and provide valuable guidance for LD thermal management.
Ultra high-power and highly efficient 9xx nm single emitters with up to 65W output power under CW operationTodt, René; Abdul Khadar, Riyaz; Riedi, Sabine; Zeghuzi, Anissa; Krammel, Christian; Rösch, Markus; Oliva, Nicolo
doi: 10.1117/12.3003705pmid: N/A
Handheld fiber laser welding is increasingly replacing arc welding as the technology of choice, driving strong demand for components that enable cost-efficient designs. In a first step, this trend has driven the development of multi-mode edge-emitting laser diodes in the 9xx nm wavelength range that, depending on emitter width, nowadays routinely achieve output power levels in the range of 35-45 W. We report on our recent developments of even more powerful single emitter laser diodes at Coherent Corp. to support novel and even more cost-efficient fiber laser architectures. Our newest generation of edge-emitting devices provides reliable output power levels in CW operation of up to 65 W from a 320 m-wide emitter.
Wavelength stabilization and feedback sensitivity of multi-kW diode laser stacksWitte, Ulrich; Dommermuth, Bastian; Weber, Felix; Raguse, Marius; Balck, Anne; Kösters, Arnd; Krause, Volker
doi: 10.1117/12.2692154pmid: N/A
In the first part of this paper, we report on a fiber-coupled wavelength-stabilized high power diode laser system with an optical output power of more than 4 kW at a wavelength of 969 nm. The spectrum is locked over the entire working range with a FWHM of less than 0.5 nm. More than 90% power is encircled within 0.7 nm. The radiation is coupled into a fiber with a core diameter of 1000 m. Additionally, we show the way for further power scaling up to 8 kW by using diode laser bars that enable higher injection current and output power. In the second part of this paper, we report on the impact of external back-reflections on the diode laser either by long term operation with VBGs or by short term operation in an experimental set-up based on a partially reflective mirror. For our standard set-up with VBG, we do not observe any feedback induced failures or degradation for operating times up to 3,000 hours. However, as expected, we do observe failures with increased feedback. In accordance with the literature, misalignment towards the p-clad can be very critical at wavelengths greater than 960 nm. The feedback-induced failure-rate increases exponentially with the injection current which make high power diode laser bars with high filling factors a very robust solution for external wavelength stabilization.
High brightness long lifetime 650nm single-mode laser diodes and arrays for display, printing, and quantum applicationsUlkuniemi, R.; Schramm, A.; Vilokkinen, V.; Nikkinen, J.; Uusimaa, P.
doi: 10.1117/12.2691906pmid: N/A
Individually addressable laser diode arrays (IAB) have been first demonstrated in near-infrared wavelengths, 8xx nm and 9xx nm, being mostly utilized in the digital printing industry. When moving towards visible wavelengths, other applications emerge. Examples of these are various display applications, including AR/VR products and head-up-displays. In addition, novel applications for narrow linewidth lasers have emerged in the field of quantum computing. In this paper, we present our latest single-mode visible array results in 650 nm region, showing up to three times improvement in brightness. In addition, we demonstrate faster stabilization of the device during life-test and reach stabler operating power of the devices. Life-tests have been run with Automatic Current Control (ACC) mode with two different operating currents, showing only minor change in output power. High stability and reliable operation combined with our IAB design are enablers for further miniaturization of device design, scalable to 100 emitters and beyond, reaching e.g. higher resolution for printing and display applications. Additionally, such design and scalability can be integrated with on-chip gratings reaching DBR and DFB operation, which enables new capabilities in quantum applications.
Time-resolved analysis of degradation in high-power broad-area lasers with quantum well and quantum dot active regionsSin, Yongkun; Feltenberger, Cassidy; Daniel, Dicky; Voegtle, Matthew; Bae, In-Tae
doi: 10.1117/12.3000500pmid: N/A
High-power broad-area lasers are critical components for space satellite communications systems. Broad-area lasers with InGaAs-AlGaAs strained Quantum Well (QW) active regions are currently used in space satellite systems. These QW lasers have shown excellent power and efficiency characteristics, but these lasers are still susceptible to COD (catastrophic optical damage) leading to catastrophic and sudden degradation. Thus, their long-term reliability in space environments is a major concern. Furthermore, our group has shown that these lasers predominantly degrade by a new failure mode due to Catastrophic Optical Bulk Damage (COBD). The 3-D confinement of carriers in InAs-GaAs Quantum Dot (QD) active region has a potential to suppress nonradiative recombination of carriers at growth or radiation induced defect sites. This feature makes the QD lasers attractive for space applications. For the present study, we employed time-resolved analysis techniques including time-resolved electroluminescence (TR-EL) and time-resolved photoluminescence (TR-PL) techniques to investigate degradation in high-power broad-area lasers. We studied broad-area lasers with two different types of active regions – strained InGaAs-AlGaAs single QW layer and ten stacks of InAs-GaAs QD layers. TR-EL techniques were employed for time-resolved analysis of degradation processes in QW and QD lasers to study the sequence of critical events including the formation and propagation of dark line defects in 110, 11̅0, and 100 directions during accelerated life-tests. TR-PL techniques were employed to measure carrier lifetimes in QW laser wafer. Lastly, we report our understanding on degradation mechanisms in broad-area lasers with QW and QD active regions.
High-brightness pumps for fiber lasers based on monolithically grating stabilized diode lasersWilkens, M.; Basler, P. S.; Eppich, B.; Fricke, J.; Ginolas, A.; Hübner, M.; Crump, P.
doi: 10.1117/12.3002553pmid: N/A
Innovation in diode laser design and technology, assembly techniques and optical design are used to realize high-brightness pump modules for application in pumping of fiber lasers. In a first demonstration, monolithically grating-stabilized diode lasers with wavelength around 970 nm are integrated into prototype modules that deliver 500 W of continuous wave TE-polarized optical power at a conversion efficiency 55% within a spectral width of 1.2 nm (95% power) in a narrow beam, suitable for low-loss coupling into a 200-µm core fiber. An especially simple opto-mechanical configuration is developed, without need for external volume Bragg gratings.
1W fiber output operation at 35 C of FBG-laser with a GaInAsP laser chip with electric field control layer for fiber Raman amplifierYoshida, J.; Kokawa, T.; Sakaguchi, K.; Tanaka, M.; Wakaba, M.; Hojo, N.; Seki, M.; Tatamida, Y.; Itoh, H.
doi: 10.1117/12.3001943pmid: N/A
In recent digital coherent transmission systems, it is necessary to improve the received Optical Signal to Noise Ratio (OSNR) after fiber transmission in order to achieve higher transmission capacity. Fiber Raman Amplifiers (FRAs) are well-known techniques for improving OSNR, especially backward FRAs, which are widely applied in high-capacity digital coherent transmission systems. However, pump lasers having higher output and lower power consumption are required since the Raman gain is small in the FRAs. As a means to realize these characteristics, a laser waveguide structure with a small optical confinement coefficient of the LD chip (low- structure) is very effective. Especially, this makes Inter-Valence Band Absorption (IVBA) could be reduced by distributing an electric field toward the substrate side, and internal loss could be reduced to improve the slope efficiency. We have proposed a novel low- structure consisting of a GaInAsP/InP electric field-controlled layer, which has an advantage of mass production. In this paper, we demonstrate 1W fiber output operation at 35 C of Fiber-Bragg grating laser modules (FBG-lasers) for Fiber Raman Amplifier using a GaInAsP laser chip with electric field control layer for the first time. In order to realize high power at high temperature operation of 35 C of laser chip temperature at a case temperature of 70 C, we optimize the design of a laser chip waveguide keeping a single transverse mode to reduce the series resistance. With an operating current of 2.7 A, FBG-laser exhibits 7.8W of power consumption with 775mW of fiber output.
Ultra-wide-aperture diode lasers with high brightness through use of buried periodic current structuringKing, B.; Arslan, S.; Della Casa, P.; Martin, D.; Boni, A.; Basler, P. S.; Thies, A.; Knigge, A.; Crump, P.
doi: 10.1117/12.3005647pmid: N/A
We report progress in the development of GaAs-based laser diodes with ultra-wide stripe widths of W = 1200 m emitting at a wavelength of = 915 nm. In order to restrict ring oscillations and higher order modes in these ultra-wide devices we utilise periodic current structuring with a period of 29 m and width of 20 m. We compare the performance of a device with current structuring realised through contact layer implantation of the device after epitaxial growth, termed a 'Contact Implant' laser, and a device with buried current structuring close to the active region of the device realised using two step epitaxial regrowth and Buried-Regrown-Implant-Structure (BRIS) technology, termed a 'BRIS' laser. Quasi-Continuous Wave (QCW) measurement of the devices show that both the 'Contact Implant' and 'BRIS' laser achieve a very high peak output power of Popt = 200 W at a power conversion efficiency of E = 59% and E = 52%, respectively, with a peak efficiency of around 70%. QCW beam-quality measurements show that the 'BRIS' laser has a much reduced 95% power content far-field angle of 9, compared to 12.7 for the 'contact implant' laser, at a power of Popt = 100 W. Under Continuous Wave (CW) operation the 'contact implant' laser reaches an output power of Popt = 68 W at E = 57% and the 'BRIS' laser reaches Popt = 53 W at E = 50%, but with a reduced far-field angle of 11.9 at Popt = 40 W for the 'BRIS' laser.
Manufacturing and reliability analysis of high-brightness blue light semiconductor laserWu, Yueting; Zhang, Fengchao; Zhang, Xinning; Zhang, Longtao; Yu, Zhenkun; Lang, Chao; Chen, Xiaohua; Ma, Wei
doi: 10.1117/12.3005608pmid: N/A
The blue semiconductor laser with a wavelength range of 450nm has developed rapidly in recent years. For high-reflective and high-thermal conductive materials represented by copper, gold and high-strength aluminum, the absorption rate of blue laser is 5-10 times than infrared lasers. Blue laser can achieve high-quality and consistent welding results, stable melt pools and no spatter. With the development of blue semiconductor laser technology, there is a growing demand for higher brightness and reliability. Based on the practical application background, we have designed and implemented a stable high-brightness blue laser. Through BPP theory and ZEMAX simulation calculation, 48pcs TO-packaged 5.5W blue lasers are coupled into a 105m core diameter 0.22NA fiber using polarization and optical fiber coupling technology. More than 250W output power is obtained with coupling efficiency exceeds 90% and electro-optical efficiency exceeds 35%. The high brightness blue laser has passed various reliability tests including accelerated aging for 7000 hours, 85C high temperature storage, -40C low temperature storage, -20C to approximately 70C temperature cycling test, vibration and mechanical shock test. The stable high-brightness blue laser finds significant applications in medical, 3D printing and welding.