Narrow-beam high-power twin-channel laser with reduced sidelobes

We present a version of the twin-channel laser with reduced dimensions. This version has improved yields of high-power lasers (Pmax ~ 120 mW at 50% duty cycle) with single-lobe far-field distributions. These far-field patterns exhibit almost no sidelobes, a fact that can be explained by the reduced dimensions.     

Low-loss low-confinement GaAs-AlGaAs DQW laser diode with opticaltrap layer for high-power operation

A low-confinement asymmetric GaAs-AlGaAs double-quantum-well molecular-beam-epitaxy grown laser diode structure with optical trap layer is characterized, The value of the internal absorption coefficient is as low as 1.4 cm^-1, while keeping the series resistance at values comparable cm with symmetrical quantum-well gradient index structures in the same material system. Uncoated devices show COD values of 35 mW/μm. If coated, this should scale to about 90 mW/μm. The threshold current density is about 1000 A/cm² for 2-mm-long devices and a considerable part of it is probably due to recombination in the optical trap layer. Fundamental mode operation is limited to 120-180 mW for 6.5-μm-wide ridge waveguide uncoated devices and to 200-300 mW for 13.5-μm-wide ones, because of thermal waveguiding effects. These values are measured under pulsed conditions, 10 μs/l ms     

Improved current efficiency in organic light-emitting devices with a hole blocking layer

A hole-blocking layer (HBL) of 4,7-diphenyl-1,10-phenanthroline (BPhen) is incorporated between the emitting layer (EML) and the electron transport layer (ETL) for a tris-(8-hydroxyqunoline)aluminum based organic light-emitting device (OLED). Such a structure helps to reduce the hole-leakage to the cathode, resulting in an improved current effi-ciency. The BPhen improves the balance of hole and electron injections. The current efficiency is improved compared with that of the device without the blocking layer. The highest luminous efficiency of the device with 6 nm BPhen acting as a blocking layer is 3.44 cd/A at 8 V, which is improved by nearly 1.5 times as compared with that of the de-vice without it.     

A short-period GaAs-AlGaAs quantum-wire array laser with a submicrometer current blocking layer

The structure and device characteristics of a 700-nm-pitch GaAs-AlGaAs quantum-wire array laser (QWAL) with a dielectric defined current blocking layer are reported. The high wire density of the QWAL has been expected to yield more efficient carrier capture, but large spacing between the quantum wires was found to deteriorate the laser characteristics. In this work, we have improved electrical confinement into the active regions by incorporating a SiO/sub 2/ film onto the large spacing. Room-temperature pulsed operation with an output power of 9 mW at 191-mA injection current was achieved for a 200/spl times/500 /spl mu/m laser with uncoated facet. The threshold current density was 0.14 kA/cm/sup 2/. The dependence of the threshold current and the maximum power on the cavity length and width was also studied.     

Ten-thousand-hours CW operation of 780 nm high-power AlGaAs laser with thin-tapered thickness active layer

The authors investigated the effectiveness of the T/sup 3/ (thin-tapered thickness active layer) structure in reducing the carrier density in the active layer as well as the optical density near the mirror. 780 nm AlGaAs lasers with this structure have been operating under 50 degrees C, 30 mW CW (continuous wave) conditions over 10/sup 4/ h with little degradation. The minimal degradation rate is about 0.45%/10/sup 3/ h.<>     

Native-oxidized InAlAs blocking layer buried heterostructureInGaAsP-InP MQW laser for high-temperature operation

A novel idea of InAlAs native oxide utilized to replace the p-n-p-n thyristor blocking layer and improve the high-temperature performance of the buried heterostructure first proposed and demonstrated. A temperature (To) of 50 K is achieved from an InAlAs native oxide buried heterostructure (NOBH) InGaAsP-InP multiquantum-well laser with 1.5-μm-wide diode leakage passage path. The threshold current and slope efficiency of NOBH laser changes from 5.6 mA, 0.23 mW/mA to 28 mA, 0.11 mW/mA with the operating temperature changing from 20°C to 100°C. It is comparable to conventional p-n reverse biased junction BH laser with minimized diode leakage current, and is much better than the buried ridge strip with proton implanted laterally confinement laser     

Quasi-CW high-power mercury laser

Laser action on a new line (lambda = 6501.5Å) with true CW potential has been achieved in a pulsed low-pressure Hg discharge. The highest power observed was 40 W. A laser pulsewidth of 0.5 ms, limited by the apparatus, was achieved.     

Modeling of the optical characteristics for twin-channel laser (TCL) structures

The twin-channel laser (TCL) structure was the first laser design which incorporated the use of optical gain in the regions between the elements of an array-type device. In this paper, we describe the important parameters affecting the performance of TCL devices and extend our concepts to multielement (n > 2) laser arrays. Our calculations indicate that the presence of a uniform gain distribution over the width of the array is necessary for the excitation of the fundamental array mode and to achieve a single lobe far field. Secondly, lateral array mode stability is drastically reduced for arrays having many elements (n > 2) and will be difficult to achieve in practice. Lastly, we find that the near-field intensity in laser array structures is more spatially sensitive to asymetric perturbations induced by either current or geometry nonuniformities than single-element devices. We believe that some of these problems can possibly be minimized by the use of a new laser array geometry which incorporates an unequal number of array elements along the cavity length in order to spatially filter the unwanted array modes.     

A 780 nm high-power and highly reliable laser diode with a longcavity and a thin tapered-thickness active layer

Conventional AlGaAs laser diodes with uniform thickness active layers of various cavity lengths are investigated. It is recognized that the extension of the cavity length is effective in the improvement of the maximum output power, the temperature characteristics, and the operating life in high-temperature conditions. A 780-nm, high-power laser diode having a 350-μm-long cavity with a thin tapered-thickness active layer was fabricated. The optical power density near the mirror facets, the thermal resistance, the current density, and the carrier density were reduced by this structure. The laser emitted over 100 mW of CW (continuous-wave) output power at temperatures up to 80°C. A maximum output power level of 160 mW was achieved at room temperature. The fundamental transverse mode was confirmed at least up to 120 mW     

高功率密度激光辐射效应

本文描述了在高功率密度激光辐射下,光与物质之间的相互作用机理和实验装置,讨论了强光束自陷现象和受激布里渊散射效应,实验观察了某些材料的破裂与损坏现象,初步分析了实际发生过程的原因,给出了一些实验资料。这些对于防止激光器件、光学系统损坏以及大气传输等有一定参考价值。     

Coherent optical communication with injection-locked high-power semiconductor laser array

Heterodyne FSK communication at 110 Mbit/s is demonstrated with an injection-locked high-power 20-stripe semiconductor laser array. It is shown that a high-power (>300 mW) coherent optical transmitter can be constructed without penalty in bit error rate performance.<>     

高功率窄脉冲激光发射电路分析

激光发射电路是激光近炸引信系统的重要组成部分,其技术指标直接影响整个激光引信系统的工作性能.实现激光的高功率、窄脉冲是提高激光引信系统作用距离、动态探测精度和抗云雾干扰能力的重要手段.但是,由于受激光器、驱动电路分布参数和工艺技术的影响,当激光脉冲宽度窄到一定程度时,激光脉冲峰值功率明显下降,要实现小体积的高功率、窄脉冲激光发射将面临许多实际问题.针对这一现象,从理论上对激光发射电路进行了分析,通过PSPICE软件仿真提出问题的所在,即激光器的寄生电感和放电回路杂散参数的存在严重影响了激光脉冲前沿速度和峰值功率.从驱动电路设计、元器件和激光器的选择与电路板布局布线出发,给出了相应的解决方法.     

A high-power 140 GHz ammonia laser

-Power levels of 17 kW in 0.7 μs pulses have been obtained from the 2.14 mm transition of NH3when optically pumped by a 65 J CO2TEA laser. Photon conversion efficiencies of 11 percent have been achieved. This is the first high-power laser line observed to work in the 140 GHz atmospheric window.     

高功率铜蒸气激光器的发展

总结了近几年来大口径、高功率铜蒸气激光器实验和理论方面的工作，讨论了高功率铜蒸气激光器结构、大口径铜节气激光器模型和工作物质的重大改进，展望了高功率铜节气激光器实验及理论方面的进展及可行性方案。     

A simple high-power pulsed nitrogen laser

An output of 500 kW peak power at 3371 Å and 25 pps is obtained from a pulsed nitrogen laser. A water capacitor is employed for energy storage, resulting in a simpler laser construction. The pulse duration is 10-15 ns, providing very high energy for pumping ultra-narrow-band dye lasers.     

Testing of high-power semiconductor laser bars

A measurement system called laser bar prober for characterizing high-power semiconductor edge-emitting laser bars is described. The laser bar prober is fully automated to handle testing of large numbers of lasers, is multifunctional to measure various laser characteristics and is accurate in predicting performance of fully mounted lasers. The bar prober has been proven to be an effective instrument for screening lasers during manufacturing process as well as an indispensable tool for providing rapid feedback to the development of new laser structures. In this paper, the design of the laser bar prober is described and a few examples of its applications are given; in particular, a time-resolved technique to correlate the measurement data of a laser within a laser bar to those of a fully mounted laser is demonstrated.     

A high-power pulsed xenon ion laser

Over 80 kW of peak power has been obtained on the combined visible lines of a pulsed xenon ion laser. Light pulse shapes of the strongest lines are discussed.