Power conversion efficiency of semiconductor injection lasers and laser arrays in CW operation

In many applications it is important to optimize the power conversion efficiency of semiconductor lasers and laser arrays. A method for calculating this efficiency which takes into account temperature effects is described, and some calculated results are presented and discussed. It is found that under certain conditions, a small increase in the thermal resistance of the device can result in a large reduction of its efficiency. Temperature effects are important in high-power semiconductor lasers, and in particular in laser arrays, where low thermal resistance heat sinking may be crucial to the device operation.     

CW injection seeding of a modelocked semiconductor laser

The authors extended the injection locking technique to control the output of a modelocked semiconductor laser with an external continuous-wave (CW) signal. With this injection seeding technique, over 8 mW of average power in 30 ps pulses with side cluster suppression of over 20 dB was obtained from an actively modelocked AlGaAs semiconductor laser. This average output power compares favorably with the 12 mW W output power of the extended resonator. The frequency spectrum of the laser is determined by the background noise level as set by the spontaneous emission. Injection seeding overrides the noise and concentrates over 99% of the available energy in a single nearly transform-limited pulse     

室温连续工作的可见光半导体激光器

本文报告我们研制成功的室温连续工作的可见光GaAlAs半导体激光器。发射的波长约7600且,所有电光参数跟红外光GaAs-GaAlAs双异质结激光器基本上一致。     

TJS laser with buried p-region for high temperature CW operation

A transverse-junction-stripe (TJS) laser with a buried p-region in a substrate has been newly developed. The temperature dependence of the threshold current is much improved so that it can operate continuously up to 110°C. Even when mounted upside up it can show a CW operation at a temperature as high as 80°C.     

CW operation of semiconductor ring lasers

Semiconductor ring lasers have been fabricated in single quantum well material using electron-beam lithography and SiCl/sub 4/ dry etching. CW operation has been achieved in 84 mu m diameter rings at a threshold current of 24 mA. This low value makes the structure very suitable for monolithic integration in optoelectronic circuits.<>     

CW operation of corner cavity semiconductor lasers

Etched facet semiconductor lasers have been fabricated and tested under CW operating conditions. The lasers consist of stripes formed by proton implantation, a total internal reflection (TIR) corner, and an output coupling facet. Devices with a variety of output coupling geometries were fabricated. Laser threshold currents and spectral characteristics were measured. Threshold current levels of devices with several different aperture sizes are compared to those of structures with standard Fabry-Perot reflectors     

高温CW半导体激光器的阈值电流

用载流子速率方程分析了高温CW半导体激光器(LD)阈值电流(I_(th))与温度(T)的关系.数值计算结果分别给出了与T有关的腔内损耗、双分子复合和俄歇过程以及载流子泄漏效应对I_(th)的贡献大小.     

A 1.54-μm monolithic semiconductor ring laser: CW andmode-locked operation

The authors have fabricated a monolithic semiconductor ring laser with a diameter of 3.0 mm. A straight tangent waveguide provides two output ports through evanescent coupling. The laser, which exhibits a threshold current of 157 mA, operates in a single longitudinal mode with a linewidth of 900 kHz at a wavelength of 1.54 μm. The device has been actively mode-locked at the fundamental resonance frequency of 9.0 GHz, yielding 27-ps pulses with a time-bandwidth product of 0.47. Differences in the characteristics of the pulses emitted from the two output ports indicate counterpropagating pulse trains, which because of the mode-locking scheme must collide in the modulated gain section     

CW room-temperature operation of Y-junction semiconductor ring lasers

CW room-temperature lasing in Y-junction semiconductor ring lasers with radii as small as 50 mu m is reported. The dependence of the threshold current density on device dimensions is examined for radii in the range 50-200 mu m and for waveguide widths of 2-8 mu m. From these quantum-well devices, approximately 1 mW of CW single-frequency Te-polarised lasing output is obtained.<>     

CW laser operation of Nd:YLF

CW laser operation of Nd:YLF is reported for the first time and, in a comparison to Nd:YAG, exhibits a lower threshold and higher single-mode average power. The TEM00mode volume of Nd: YLF was observed to be a factor of four larger than Nd:YAG, resulting in twice the TEM00mode average power. This result is attributed to the substantially lower thermal lensing of YLF with respect to YAG. In comparative measurements the stimulated emission cross section of Nd:YLF was found to be1.8 times 10^{-19}cm²for the π oscillation and1.2 times 10^{-19}cm²for the σ oscillation, as compared to2.4 times 10^{-19}cm²for Nd:YAG. The spectroscopic and lasing parameters of Nd:YLF indicate a potential for this material in high peak and average powerQ-switched applications.     

636 nm room temperature CW operation by heterobarrier blocking structure InGaAlP laser diodes

636 nm room temperature CW operation has been achieved by heterobarrier blocking structure InGaAlP laser diodes with a quaternary active layer. This structure was fabricated by two-step metal-organic chemical vapour deposition. The threshold current was 102 mA at 20 degrees C and CW operation of 3 mW was attained at up to 48 degrees C.<>     

YAG laser operation by semiconductor laser pumping

Yttrium aluminum garnet (YAG) laser operation has been achieved using a single gallium arsenide laser diode as the pump. Repetition rates of 200 pulses per second have been achieved in initial experiments. Compared to flashlamp pumping, semiconductor laser pumping requires less. than 5 percent of the light energy to accomplish YAG lasing. Extraordinary repeatability of laser output, pulse to pulse, has been obtained.     

Improved heat-sink design for coherent laser arrays

A heat sink with a cap whose lateral dimensions match the width of a laser array will remarkably improve the temperature uniformity in the array facilitating phase-locked operation.     

5000小时室温连续激射GaAs/AlGaAs双异质结激光器

一、引言 半导体激光器采用双异质结构(DH),对有源层内的注入载流子及辐射光场进行限域,使得阈电流密度迅速下降为～1×10~3安培/厘米~2,1970年实现了室温连续激射。双异质结激光器是光纤通讯和精密测距的较理想光源,但急待解决稳定性和可靠性问题。自从对DH激光器退化机理有了比较清楚了解之后,激光器寿命基本上每年提高半个至一个数量级。到1976年美国Bell公司通过升温加速老化试验推断激光器寿命可望达到100万小时。也已采用多种方式制作各     

Room temperature CW operation of orange light (625 nm) emitting InGaAlP laser

An InGaAlP laser operating under continuous wave excitation, having a record short wavelength of 625 nm at room temperature has been constructed. This was accomplished employing a tensile strained ( Delta a/a=-1%) multiquantum well active region and a six pair multiquantum barrier structure.<>     

Fabry-Perot semiconductor laser injection locking

Injection locking of a semiconductor laser is studied using a Fabry-Perot (FP) model. For low injection powers the FP model gives the same results as the rate equation model. At higher injection powers, the FP laser has an unlimited injection locking bandwidth; however, regions of the bandwidth are dynamically unstable. The influence of the linewidth enhancement factor on injection locking and its stability are also studied using the FP model. Finite values of the linewidth enhancement factor lead to increased locking bandwidth, asymmetry in the locking range and a saddle-node bifurcation in the injection locked solutions, of which only lower carrier density arm has linearly stable solutions.     

Lateral grating array high power CW visible semiconductor laser

A periodic, grating-like array of substrate grooves oriented parallel to the longitudinal axis of the laser provides a small periodic lateral thickness modulation of the active region of an MO-CVD-grown Ga1?xAlxAs laser producing phase-locked operation at 7680 ?. CW output powers as high as 138 mW/facet have been obtained.     

808nm连续波2000W半导体激光器垂直叠阵

为了全面提高大功率半导体激光器的性能和功率,采用双面散热技术,优化了大功率半导体激光器垂直叠阵和单bar器件的热管理和热设计,使得808nm单bar半导体激光器在连续波工作模式下的功率达到100W;808nm 20bar垂直叠阵功率达到2000 W.对微通道液体制冷大功率半导体激光器叠阵和单bar半导体激光器器件的LI...     

Partition noise in semiconductor lasers under CW and pulsed operation

A numerical model which simulates the mode partition noise in semiconductor lasers under CW as well as pulsed operation is presented. The noise levels in the individual modes under CW operation are in agreement with those predicted by an analytic small-signal model. Under simulated pulse modulation with pulse repetition frequencies of 633 MHz and 2.2 GHz, the probability density functions for the relative photon numbers in the individual modes are found. The data allow for an evaluation of the mode partition parameterk. For the central modes,kfactors are in the range of 0.31-0.42, depending on bias level and modulation frequency. Weaker side modes carrying less than 5 percent of the total output havekfactors smaller than 0.16.     

High temperature CW operation of p-substrate buried crescent laser diode emitting at 1.3 ?m

A 1.3 ?m InGaAsP/InP buried crescent laser diode has been fabricated on p-InP substrate. The laser diode has a low threshold current, as low as 10 mA. It operates at the output power of 5 mW under CW condition at temperatures higher nary aging test at 70°C with a constant light output of 5 mW, the lasers have been operating stably for more than 1000 h.