High-power Semiconductor Lasers Research Articles

High-power semiconductor laser with a narrow linewidth based on transverse photonic crystal

Broad-area lasers (BA) are practical for producing high output power. However, under a high current operation, high-order modes are easily excited, resulting in the broadened linewidth. Here, based on mode engineering of double-side transverse photonic crystals (TPCs) combined with a longitudinal high-order surface grating, a narrow-linewidth electrically-pumped broad-area laser with high power emission only using I-line lithography is demonstrated. By matching the high-order modes of the wide main waveguide with TPC bands, the effective volume of the high-order modes is expanded, while the fundamental mode remains unchanged. Then, single-lateral mode operation is achieved by selective pumping only for the main waveguide due to the significant distinction in modal gain between the fundamental mode and the high-order modes. In addition, a 27-order grating is constructed above the main waveguide to keep the laser operating in single-longitudinal mode. In the experiment, the device shows an output power of 115 mW, a lasing wavelength of 1552.94 nm with a side-mode suppression ratio (SMSR) of 59.26 dB, a narrow linewidth of 443 kHz, and a relative intensity noise (RIN) < -135 dB/Hz at 600 mA, thus has the potential to meet the needs in fields such as coherent optical communication and LiDAR.

High-power distributed feedback laser diode arrays with narrow spectral width over a wide temperature range

High-power semiconductor lasers with stabilized wavelengths are recognized as exemplary pumping sources for solid-state lasers. This study introduces distributed feedback (DFB) laser diode arrays designed to maintain an extensive temperature locking range. We report experimentally on high-power 808 nm DFB laser diode arrays. The first-order sinusoidal grating was fabricated using nanoimprint lithography, succeeded by inductively coupled plasma (ICP) dry etching and subsequent wet polishing. These 808 nm DFB laser diode arrays have demonstrated a measured output power of 134 W under a pulsed current of 150 A, with the heat sink temperature maintained at 25°C. The slope efficiency was determined to be 1.1 W/A. At a current of 150 A, the laser operated with a narrow spectral width over a wide temperature range, extending from −30 to 90°C, with a temperature drift coefficient of 0.0595 nm/K.

Design of Laser-Powered Opto-Electrical Current Transformer and Its Application in Electrical Automation of Substations

The novel power equipment represented by the Opto-Electrical Current Transformer (OECT) possesses unparalleled advantages compared to traditional Current Transformers (CTs), rendering it with vast potential in power systems. In the design of OECT, this study employs laser power supply and focuses on the overall perspective, particularly the design of the laser power supply module and the optical fiber digital transmission module. The laser power supply module selects a high-power semiconductor laser to provide power to the circuit, incorporating line filters, thermistor resistors, and a laser overcurrent protection circuit. An automatic temperature control circuit based on PI regulation is utilized to stabilize the working temperature of the laser diode (LD). The photoelectric conversion device PPC-6E achieves a maximum photoelectric conversion efficiency of 40%, and the MAX639 DC–DC conversion chip ensures stable output voltage. The optical fiber digital transmission module adopts a circuit composed of multiple NOR gate logic for electro-optical conversion, a low-power driving circuit based on the 74LVC1G07 chip, and the HFBR-2412 photoelectric converter to simplify the circuit board design. To achieve a higher communication baud rate, a quartz multimode optical fiber with a diameter of 62.5 μm is chosen. In the experimental phase, a simulation of high-power AC power with equal turns is conducted. The linearity/temperature test results demonstrate that the designed OECT in this study meets expectations. In the electrical automation test of substations, a comparison between traditional CTs and the designed OECT is carried out using traditional protection algorithms and optical differential protection algorithms. The results indicate that, compared to traditional protection algorithms, the optical differential algorithm using the designed OECT achieves faster protection times.

Stability improvement of high-power semiconductor laser diode regulators used in infrared solid-state laser applications

Stability improvement of high-power semiconductor laser diode regulators used in infrared solid-state laser applications

Integrated degradation-based burn-in and maintenance model for heterogeneous and highly reliable items

In modern industries, manufacturers employ burn-in procedures to detect and remove faulty units before they are put into use. However, with the increasing prevalence of highly reliable items, traditional lifetime-based burn-in approaches may not be effective. So, the degradation-based approach screening units based on their degradation levels becomes more prevalent. Ensuring the safety and reliability of a system requires maintenance, making it crucial to find optimal burn-in settings and maintenance time simultaneously. This paper presents an integrated degradation-based burn-in and maintenance model, assuming a population comprising several heterogeneous subpopulations. The model has four decision parameters, three for the burn-in settings, and one for maintenance. To determine the parameters optimally, two optimization problems are presented. The first problem minimizes expected cost function by considering availability and safety as constraints. The second problem maximizes a joint function of cost and availability given a safety constraint. A comprehensive numerical analysis is conducted to offer valuable insights for practitioners. The proposed approach is compared to a stand-alone planned maintenance model, as well as models that neglect availability and safety constraints. The results of the comparative studies show the integrated model outperforms. The proposed model is illustrated using a case study on high-power semiconductor lasers.

Fiber Coupling System and Beam Shaping Design for High-Power Semiconductor Laser Stack

Fiber Coupling System and Beam Shaping Design for High-Power Semiconductor Laser Stack

Research on the fabrication of high-power semiconductor lasers by impurity-free vacancy disordering

Research on the fabrication of high-power semiconductor lasers by impurity-free vacancy disordering

Implementation of energy barrier layers for 1550 nm high-power laser diodes

The influence of a thin AlInAs energy barrier on the efficiency of 1550 nm high-power semiconductor lasers efficiency has been experimentally studied. It was shown that the position and number of barriers in an asymmetric laser heterostructure based on a 1.8–1.9 μm thick waveguide has a significant effect on the output optical power. It is shown that in a barrierless structure, the main reason for radiative efficiency decrease is internal quantum yield drop due to the absence of an energy barrier for the type-II heterojunction at the waveguide-p-cladding interface and electron leakage to the p-emitter layer. It is demonstrated that the implementation of single AlInAs energy barrier layer on waveguide-p-cladding heterojunction allows significantly increase laser diode maximum output power. 2 W maximum CW optical power has been achieved from 40 μm aperture laser diode at heatsink temperature 25 °C.

Laser isotope separation to study for the neutrino-less double beta decay of 48Ca

The laser isotope separation (LIS) system is being developed for the study of neutrino-less double beta decay of 48Ca. A proof-of-principle experiment has been successfully conducted, and development of a mass production (∼1 mol/year) system is currently underway. For stable and efficient production, we are preparing an atomic beam system capable of producing a well-collimated beam with sufficient flux and a high-power semiconductor laser system with stable frequency over a long period of time.

Heating Dynamics of the Active Region of High-Power Semiconductor Lasers (λ = 1060 nm) with an Ultra-Wide Aperture (800 µm) in the Quasi-CW Mode

Heating Dynamics of the Active Region of High-Power Semiconductor Lasers (λ = 1060 nm) with an Ultra-Wide Aperture (800 µm) in the Quasi-CW Mode

High-brightness scalable continuous-wave single-mode photonic-crystal laser

Realizing large-scale single-mode, high-power, high-beam-quality semiconductor lasers, which rival (or even replace) bulky gas and solid-state lasers, is one of the ultimate goals of photonics and laser physics. Conventional high-power semiconductor lasers, however, inevitably suffer from poor beam quality owing to the onset of many-mode oscillation1,2, and, moreover, the oscillation is destabilized by disruptive thermal effects under continuous-wave (CW) operation3,4. Here, we surmount these challenges by developing large-scale photonic-crystal surface-emitting lasers with controlled Hermitian and non-Hermitian couplings inside the photonic crystal and a pre-installed spatial distribution of the lattice constant, which maintains these couplings even under CW conditions. A CW output power exceeding 50 W with purely single-mode oscillation and an exceptionally narrow beam divergence of 0.05° has been achieved for photonic-crystal surface-emitting lasers with a large resonant diameter of 3 mm, corresponding to over 10,000 wavelengths in the material. The brightness, a figure of merit encapsulating both output power and beam quality, reaches 1 GW cm−2 sr−1, which rivals those of existing bulky lasers. Our work is an important milestone toward the advent of single-mode 1-kW-class semiconductor lasers, which are expected to replace conventional, bulkier lasers in the near future.

Technology Research on the Preparation of DBR Semiconductor Lasers by Electron Beam Lithography

In order to obtain the high performance output of DBR semiconductor laser, the grating pattern is photolithographed by electron beam exposure technique, and the grating structure is fabricated by combining inductively coupled plasma etching and other processes. By controlling the exposure dose of electron beam lithography and optimizing the graphic line width, a grating shape that meets the device fabrication requirements is finally obtained. The test results show that the grating line width meets the experimental requirements and the grating sidewall steepness is good; the reflectivity and other indicators meet the device fabrication requirements, laying the foundation for the performance optimization of high-power semiconductor lasers.

High-Power Semiconductor Laser Fabricated by Standard Photolithography for Direct Modulation

High-power semiconductor laser with an integrated master oscillator power amplifier (MOPA) based on the surface-slotted structure is demonstrated. The lasing wavelength of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.5~\mu \text{m}$ </tex-math></inline-formula> is achieved by using a group of micron-level slots fabricated by standard photolithography. The laser exhibits continuous-wave output power of up to 225 mW in the single-mode operation at room temperature. At the maximum output power, the modulation bandwidth is larger than 7 GHz, demonstrating the excellent performance of the MOPA based on the surface-slotted structure.

Beam Shaping Technique for 5-mm Fiber-coupled Laser Diode Bars with Lens Group

In the last few years, fiber-coupled diode lasers have shown massive applications in many fields of communication and scientific research. Particularly, the pumping of solid-state lasers is a key application for more powerful diode lasers enabling good solutions in various laser micro methods like metal cutting, sintering, structuring as well as drilling. In this work, a simple beam shaping method is demonstrated for coupling a high-power semiconductor laser diode into multi-mode fiber optic using optical lenses. The optical lenses as beam transformation components are utilized to reshape the asymmetrical irradiation of the diode laser bar and to circularize the laser beam. Using this simple method, compact, high-output-power, and high-brightness fiber-coupled laser diode systems are achieved. The obtained results show that the entire optical coupling efficiency of the system is more than 65%.

High-Power Supersymmetric Semiconductor Laser with a Narrow Linewidth

We have designed and fabricated a kind of supersymmetric slotted Fabry–Perot semiconductor laser near 1550 nm to achieve a single-mode, high-power, and narrow-linewidth operation. The structure of the laser is composed of an electrically pumped broad ridge waveguide in the middle to provide optical gain, a group of periodic slots etched near the front facet to suppress the extra longitudinal modes and achieve a narrow linewidth, and a pair of passive superpartner waveguides located on both sides to filter out the high-order lateral modes in the broad waveguide. The device measured under the temperature of 25 °C shows an output power of 113 mW, a single-lobe lateral far-field distribution with the full width at half maximum of 7.8°, a peak wavelength of 1559.7 nm with the side-mode suppression ratio of 48.5 dB, and an intrinsic linewidth of 230 kHz at the bias current of 800 mA. The device is a promising candidate for cost-effective light sources for coherent communication systems and LiDARs.

Study of Temperature Effects on the Design of Active Region for 808 nm High-Power Semiconductor Laser

High-power, broad-area, semiconductor lasers are attractive sources for material processing, aerospace, and laser pumping. The design of the active region is crucial to achieve the required high power and electro-optical conversion efficiency, since the temperature significantly affects the performance of the quantum well, including the internal quantum efficiency and mode gain. In this work, the temperature effects on the active region of a 808 nm high-power semiconductor laser were investigated theoretically and experimentally. The simulations were performed with a Quasi-3D model, which involved complete steady-state semiconductor and carrier confinement efficiency combined with a new mathematical method. The critical aluminum content of the quantum barrier was proposed and the relationship between temperature and various loss sources was disclosed in the temperature range of 213 to 333 K, which provides a reliable reference for the design of epitaxial structures of high-power semiconductor lasers in different operating conditions. Subsequently, the optimized epitaxial structure was determined and used to fabricate standard laser bar chips with a cavity length of 2 mm. The experimental electro-optical conversion efficiency of 71% was demonstrated with a slope efficiency of 1.34 W/A and an injection current of 600 A at the heatsink temperature of 223 K. A record high electro-optical conversion efficiency of 73.5% was reached at the injection current of 400 A, while the carrier confinement efficiency was as high as 98%.

Research and Progress of High-Power Semiconductor Lasers with High Beam Quality

Research and Progress of High-Power Semiconductor Lasers with High Beam Quality

Transient analysis of cryogenic cooling performance for high-power semiconductor lasers using flash-evaporation spray

• Transient phase-change heat transfer analysis was performed in cryogenic regimes. • A heat flux estimation method that considers an imposed heat flux was proposed. • The moderate spurt duration (Δ t = 30 s) produced preferable cooling performance. • Small-orifice-diameter nozzle has low cooling rate but high thermal efficiency. Focusing on the cryogenic cooling for the high-power semiconductor lasers to improve their output performance, this work conducted an experimental investigation on analyzing the transient cooling performance using a single-pulsed flash-evaporation spray with the environmental cryogen R32. A heat flux calculation methodology that considers an imposed heat flux as a boundary condition, was first developed to assist the transient heat transfer analysis. The results provided further insight into phase-change heat transfer on the hot surface from high-temperature to cryogenic regimes through coupling the heat transfer measurements with observations of hydrodynamic liquid film formation and development. The moderate spurt duration (Δ t = 30 s) that produced a large temperature drop (109.5 °C) and high time-averaged cooling rate (24.1 W/cm 2 ) was preferable. The significant losses in droplets’ momentum and mass contributed to the fast decrease in cooling effect as nozzle-to-surface distance ( Z ) increased. Specifically, shortening Z from 50 to 10 mm not only increased the maximum surface heat flux from 19.6 to 73.6 W/cm 2 , but also broadened the temperature region with high heat flux. The nozzle with a smaller orifice diameter (0.5 mm) produced a lower cooling rate. Whereas surprisingly, its lower flow rate resulted in the lesser coolant accumulation and splashing on the hot surface, which elevated its thermal efficiency. The low spray thermal efficiencies (≤16.2%) in the present work attribute to the low liquid utilization and coverage area across the hot spot surface under the spray impact.

Processes of the Reliability and Degradation Mechanism of High-Power Semiconductor Lasers

High-power semiconductor lasers have attracted widespread attention because of their small size, easy modulation, and high conversion efficiency. They play an important role in national economic construction and national defense construction, including free-space communication; industrial processing; and the medical, aerospace, and military fields, as well as other fields. The reliability of high-power semiconductor lasers is the key point of the application system. Higher reliability is sought in the military defense and aerospace fields in particular. Reliability testing and failure analysis help to improve the performance of high-power semiconductor lasers. This article provides a basis for understanding the reliability issues of semiconductor lasers across the whole supply chain. Firstly, it explains the failure modes and causes of failure in high-power semiconductor lasers; this article also summarizes the principles and application status of accelerated aging experiments and lifetime evaluation; it also introduces common techniques used for high-power semiconductor laser failure analysis, such as the electron beam-induced current (EBIC) technique and the optical beam-induced current (OBIC) technique, etc. Finally, methods used to improve the reliability of high-power semiconductor lasers are proposed in terms of the preparation process, reliability screening, and method application.

Facet passivation process of high-power laser diodes by plasma cleaning and ZnO film

Passivation of dangling bonds at the cleaved mirror facet and its durability are fundamental features of semiconductor lasers to obtain reliable operation with a long device lifetime. The high non-radiative recombination activity of the surface states needs to be controlled to prevent the Fermi level pinning before the deposition of mirror coating materials. Here, we report the incorporation of plasma cleaning of the facet and ZnO film as a passivation layer for the fabrication of high-power semiconductor lasers. The Argon plasma cleaning process was investigated to eliminate surface contamination without damaging the cavity surface. The ZnO passivation films were systematically studied by varying the chamber pressure and sputtering power of the radio frequency (RF) sputter coating process. We obtained homogeneous and dense ZnO films with high surface quality and optical absorption coefficient of zero. By incorporating the optimum plasma cleaning and passivation layer parameters, GaAs-based laser devices with significantly improved catastrophic optical mirror damage (COMD) power were achieved. COMD threshold was increased from 11.9 W to 20.7 W. The life test results demonstrate no failure for facet cleaned and passivated devices for more than 500 h, confirming the long-term effectiveness of the process for actual device integration.