Advanced semiconductor lasers

Recent research activities in the field of advanced semiconductor lasers are reviewed with emphasis on highly stable single-wavelength lasers and surface-emitting (SE) lasers for wideband lightwave communication systems and optical parallel information processing. The operational characteristics of DSM (dynamic single-mode) lasers are summarized and requirements for high-performance operation as light sources for high-speed transmission or coherent communications are described. A type of DSM laser called the distributed-reflector (DR) laser is described as an advanced DSM laser which enables high efficiency, high power, and narrow linewidth operations. Specific features and the potential of SE lasers are summarized. Research activities and remaining problems to be solved for a breakthrough in optical parallel information processing are presented. The potential of multidimensional quantum-well structures, such as QW lasers and quantum-box lasers, is discussed in terms of superior characteristics in both stationary and dynamic operations. The present fabrication technologies for realizing high-performance lasers based on multidimensional QW structures are also presented     

High-power wavelength-tunable cladding-pumped rare-earth-doped silica fiber lasers

We describe the design and performance of cladding-pumped silica fiber lasers with high continuous-wave output powers and broad wavelength tunability in the 1, 1.5, and 2 μm spectral ranges. An ytterbium-doped fiber laser was tuned via wavelength dependent feedback provided by an external cavity containing a diffraction grating from 1027 to 1105 nm at multi-watt power levels. Similarly, high output power and wide wavelength tunability from 1540 to 1600 nm and from 1860 to 2090 nm at multi-watt output power levels has been achieved in Er-Yb co-doped and Tm-doped silica fiber lasers, respectively. A neodymium doped fiber laser was tuned from 1057 to 1118 nm at a lower power level. Limiting factors and the prospects for further improvements in performance are considered.     

长波长垂直腔面发射激光器

给出了长波长垂直腔面发射激光器的器件结构的发展现状，同时对GaInNAs／GaAs垂直腔面发射激光器进行了详细的介绍。最后，给出了所设计的新型1.3μm GaInNAs/GaAs长波长垂直外腔面发射半导体激光器的结构设计，有源区量子阱由980nm半导体激光二极管进行泵浦。这种器件设计实现了激光二极管泵浦与长波长垂直腔面发射激光器的有机结合，同时具有两者的优点。此外，本文还对器件的阈值特性和光输出功率进行了理论计算。     

Low-threshold continuous-wave 1.5-/spl mu/m GaInNAsSb lasers grown on GaAs

We present the first continuous-wave (CW) edge-emitting lasers at 1.5 /spl mu/m grown on GaAs by molecular beam epitaxy (MBE). These single quantum well (QW) devices show dramatic improvement in all areas of device performance as compared to previous reports. CW output powers as high as 140 mW (both facets) were obtained from 20 /spl mu/m /spl times/ 2450 /spl mu/m ridge-waveguide lasers possessing a threshold current density of 1.06 kA/cm/sup 2/, external quantum efficiency of 31%, and characteristic temperature T/sub 0/ of 139 K from 10/spl deg/C-60/spl deg/C. The lasing wavelength shifted 0.58 nm/K, resulting in CW laser action at 1.52 /spl mu/m at 70/spl deg/C. This is the first report of CW GaAs-based laser operation beyond 1.5 /spl mu/m. Evidence of Auger recombination and intervalence band absorption was found over the range of operation and prevented CW operation above 70/spl deg/C. Maximum CW output power was limited by insufficient thermal heatsinking; however, devices with a highly reflective (HR) coating applied to one facet produced 707 mW of pulsed output power limited by the laser driver. Similar CW output powers are expected with more sophisticated packaging and further optimization of the gain region. It is expected that such lasers will find application in next-generation optical networks as pump lasers for Raman amplifiers or doped fiber amplifiers, and could displace InP-based lasers for applications from 1.2 to 1.6 /spl mu/m.     

1.5-1.6 µm GaInAsP/InP dynamic-single-mode (DSM) lasers with distributed Bragg reflector

The theoretical bases and the experimental results of the dynamic behavior of1.5-1.6 mum GaInAsP/InP dynamic-single-mode (DSM) lasers with distributed Bragg reflector (DBR) are given. A condition for the single-mode operation of a rapidly modulated DBR laser, called a "dynamic-single-mode laser," and the dynamic spectral width were theoretically presented. Experimentally, buried-heterostructure distributed-Bragg-reflector integrated-twin-guide (BH-DBR-ITG) and buried-heterostructure butt-jointed-built-in distributed-Bragg-reflector (BH-BJB-DBR) lasers emitting at the wavelength of1.5-1.6 mum were directly modulated up to 3 GHz, and the stable single-mode operations were obtained in both types of lasers. The dynamic spectral width at the worst modulation condition was measured to be 0.27 nm, which was aboutfrac{1}{35}times smaller than that of conventional lasers.     

百瓦级1.2/1.5 μm双波长金刚石拉曼激光器（特邀）

具有高功率、高光束质量的双波长激光器在精密光谱、共振干涉测量和激光雷达等领域有着重要的应用。但是受到激光工作物质固有的光谱和增益特性制约,通过传统的粒子数反转激光器难以直接获得高功率的双波长激光输出,因此通常需要结合非线性光学频率变换技术将常规的单一波长高功率激光拓展至一个或若干个特殊波段。受激拉曼散射作为一种三阶非线性效应,具有频移大、自相位匹配和光束净化等优点,是实现高效率、高光束质量波长转换有效手段。利用具有宽光谱透过范围（>0.23 μm）、超高热导率（>2 000 W·m?1·K?1）和大拉曼频移（1 332 cm?1）等优异特性的金刚石晶体作为拉曼增益介质,通过外腔振荡结构实现了1 μm泵浦光直接向1.2 μm和1.5 μm双波长激光的高效转换,在最高稳态泵浦功率414 W的条件下获得了1.2 μm和1.5 μm功率分别为72 W和110 W的输出。该研究为实现高功率的双波长激光输出开辟了新的途径。     

Lasers and Photodetectors in Europe

This paper reviews the European activities on fiber optic semiconductor devices for optical communication. Progress in the development of lasers, LED's, and photodetectors and also first attempts of monolithic integration are reported. Emphasis is put on materials and devices for the wavelength range of 1200-1600 nm and for high-speed transmission. Results of recent work are highlighted. So, for example, extremely high reliability and high optical output power of LED's and Fabry-Perot lasers have been achieved. MOCVD growth techniques are increasingly applied for device fabrication; for lasers, highly reproducible characteristics have been demonstrated. Development of dynamic singlemode lasers (DSM) is under progress with low threshold currents and good optical characteristics reported. First electrically tunable single-mode lasers and DSM lasers with parallel coupled cavities have been realized. Long wavelength p-i-n photodetectors have reached maturity. InGaAsP and CdHgTe avalanche photodiodes show excellent properties for high-speed long-haul transmission. First steps of monolithic integration of several optical and electrical functions have been made and specifically for p-i-n-FET combinations good results have been achieved. The plans of European PTT authorities to implement fiber optics in trunk lines and subscriber loops will further push the activities on optoelectronic device technology.     

GaSb基光泵浦半导体碟片激光器的研究进展(特邀)

GaSb基光泵浦半导体碟片激光器（OP-SDLs）可以获得高光束质量和高功率的红外激光输出,是近年来新型中红外激光器件研究领域的热点。文中介绍了GaSb基光泵浦半导体碟片激光器增益芯片的外延结构和工作原理,综述了2 m波段GaSb基泵浦半导体碟片激光器的研究进展,讨论了该类激光器的波长扩展、功率提升、实现窄线宽短脉冲发射和有效热管理关键问题,评述了性能发展的主要技术方向和应用前景。     

2 μm单掺Ho固体激光器及ZnGeP2晶体应用于中长波输出的研究进展（特邀）

2 μm、中波红外3~5 μm及长波红外8~12 μm波段的激光处于大气传输窗口,在激光医疗、环境监测、激光雷达、化学遥感和红外对抗等领域有着非常广阔的应用前景。基于非线性频率转换技术,采用非线性光学晶体在实现中长波红外固体激光输出方面具有结构简单、宽调谐和高功率等技术优势。尤其是使用2 μm单掺Ho固体激光器泵浦ZnGeP₂晶体,在3~5 μm和8~10 μm中长波红外输出中性能优异。在平均输出功率方面,目前可达到102 W@3~5 μm、12.6 W@8.2 μm以及3.5 W@9.8 μm的输出水平,光束质量M2均小于3,其中中波的光光转换效率可达60%。文中针对2 μm单掺Ho固体激光器及ZnGeP₂晶体在中长波输出方面进行了总结。     

Ho∶YLF激光泵浦的长波红外ZnGeP2光参量振荡器

以2.05μm Ho∶YLF激光器作为光源,泵浦了长波ZnGeP₂光参量振荡器,实现了高效率、高重复频率的长波激光输出。激光器输出的峰值波长为8.1μm,最大输出功率为3.2 W@10 kHz,泵浦激光到长波激光的光光转换效率为12%,斜效率为19.3%,激光单脉冲宽度为27.11 ns,单脉冲能量为0.32 mJ,单脉冲峰值功率为11.8 kW,X方向的光束质量因子为4.5,Y方向的光束质量因子为4.2。     

Corrugation-pitch-modulated MQW-DFB laser with narrow spectrallinewidth (170 kHz)

A spectral linewidth of 170 kHz was achieved at a 1.5-μm wavelength in a 1200-μm long corrugation-pitch-modulated (CPM) distributed feedback (DFB) laser having multiple quantum wells (MQW). This is the narrowest linewidth ever reported for InGaAsP DFB lasers. The CPM structure is effective in maintaining the single longitudinal mode at a high output power by suppressing the spatial hole burning effect. The linewidth-power product is 400 kHz-mW, and the extrapolated residual spectral linewidth is 150 kHz     

High temperature operation of lambda =1.5 mu m tensile strained multiple quantum well SIPBH lasers

The high temperature operation of 1.5 mu m wavelength, strained-layer multiple quantum well, semi-insulating planar buried heterostructure lasers is reported. The lasers, which are grown by low-pressure organometallic vapour phase epitaxy and which have four 1.6% tensile strained In/sub 0.3/Ga/sub 0.7/As wells (thickness 8 nm), operate in CW mode up to heatsink temperatures of 140 degrees C. The CW output power at 100 degrees C is 26 mW per facet. These results are a marked improvement when compared to data reported thus far for 1.5 mu m wavelength lasers.<>     

光纤喇曼激光器及多波长输出的分析

为了优化设计光纤喇曼激光器的各项参数,采用喇曼激光器的基本理论模型模拟分析了用DCF光纤做增益介质的光纤喇曼激光器的输出特性,提供了激光器优化设计的方法;通过改变光纤的长度和输出端面的耦合效率得到最优的激光输出;以及改变泵浦功率时输出激光功率的变化情况;并进一步分析了多波长的光纤激光器,得到四波长输出的光纤激光器。     

大功率体光栅外腔半导体激光器的输出特性

宽条形大功率半导体激光器(LD)存在光谱温漂系数大、光谱宽度宽的缺点,为了改善宽条形大功率半导体激光器的光谱特性,采用一种体光栅(VBG)离轴外腔方法实现了宽条形大功率半导体激光器光谱特性的明显改善和高效率工作.宽条形半导体激光器的外腔结构主要包括激光器输出光束的快、慢轴准直光学透镜和离轴放置的体光栅.宽条形半导体激光器的激射条宽为100μm,当激光器工作电流为4.0 A时,外腔激光器的输出功率高达3.4 W,斜率效率为1.0 W/A,光谱宽度由自由出射条件下的2~3 nm减少为0.2 nm,峰值波长的温漂系数小于0.015 nm/℃.     

Analysis of large-signal dynamic characteristics of 10-Gb/s tunable distributed Bragg reflector lasers integrated with electroabsorption modulator and semiconductor optical amplifier based on the time-dependent transfer matrix method

We investigate large-signal dynamic characteristics of tunable distributed Bragg reflector (DBR) lasers with different structures. Because of high chirp and complex structures of tunable DBR lasers, it is difficult to accurately analyze large signal chirp and output pulse shapes with analytical models. Therefore, we apply a numerical model based on the time-dependent transfer matrix method to tunable DBR lasers integrated with electroabsorption modulator (EAM) and semiconductor optical amplifier (SOA). Using this model, we find a suitable /spl alpha/-parameter range in the Bragg grating section (/spl alpha//sub Bragg/-parameter) that produces the tolerable wavelength chirp while maintaining a proper tuning range. To employ the tunable lasers in wavelength division multiplexed networks and improve flexibility of the networks, the tunable lasers should have high output power and low wavelength chirp. According to our simulation results, the EAM section had better be located in between SOA and DBR laser sections to obtain high output power and low wavelength chirp.     

Midinfrared holmium fiber lasers

The use of the high-power Tm/sup 3+/-doped silica fiber laser as a pump source for Ho/sup 3+/-doped silica and Ho/sup 3+/-doped fluoride fiber lasers for the generation of 2.1-/spl mu/m radiation is demonstrated. The Ho/sup 3+/-doped silica fiber laser produced a maximum output power of 1.5 W at a slope efficiency of /spl sim/82%; one of the highest slope efficiencies measured for a fiber laser. In a nonoptimized but similar fiber laser arrangement, a Ho/sup 3+/-doped fluoride fiber laser produced an output power of 0.38 W at 2.08 /spl mu/m at a slope efficiency of /spl sim/50%. A Raman fiber laser operating at 1160 nm was also used to pump a Ho/sup 3+/-doped fluoride fiber laser operating at a wavelength of 2.86 /spl mu/m. An output power of 0.31W was produced at a slope efficiency of 10%. The energy transfer upconversion process that depopulates the lower laser level in this case operates at a higher efficiency when the pump wavelength is closer to the absorption peak of the /sup 5/I/sub 6/ energy level, however, this energy transfer process does not impede to a great extent the performance of the Ho/sup 3+/-doped fluoride fiber laser based on the /spl sim/2.1/spl mu/m laser transition.     

面向超短脉冲激光器泵浦源的驱动系统设计及应用

设计并实现了一种用于超短脉冲激光器泵浦源的驱动系统。该系统可以同时为五路半导体激光器提供高精度、高稳定度、高灵活性的恒温控制和恒流驱动。为了提高驱动系统的灵活性和可集成度,硬件部分采用上位机、控制、驱动、供电分开的模块化设计方案;基于嵌入式实时操作系统μC/OS-III开发了系统驱动程序,提高了实时性和扩展性,输出校正部分采用遗传算法优化的增量式PID算法,减少了系统的超调量和到达动态平衡的时间;驱动系统具有完备的保护措施,如软启动和关闭、驱动回路检测、过温保护等功能,确保了泵浦源的稳定运行。在实际应用中,半导体激光器温度稳定度优于0.035%,驱动系统输出电流稳定度优于0.001%。将研制的驱动系统集成到1.5 μm飞秒光纤激光器中驱动五路半导体激光泵浦源,获得的种子激光、放大器的输出激光脉冲光谱、脉冲序列和单脉冲均可稳定运行;经过连续3 h的测试,1.5 μm飞秒光纤激光器的输出功率稳定度为0.16%。     

大功率InGaAsP/InGaP/GaAs激光器特性研究

介绍了无铝激光器的优点 ;利用 LP-MOVPE生长了 In Ga As P/In Ga P/Ga As分别限制异质结构单量子阱 (SCH-SQW)结构 ,讨论了激光器的腔长对特征温度的影响。对于条宽 1 0 0 μm、腔长 1 mm腔面未镀膜的激光器 ,连续输出光功率为 1 .2 W,阈值电流密度为 41 0 A/cm2 ,外微分量子效率为 62 % ,并进行了可靠性实验。     

1.5μm波段乙炔气体稳频光纤光栅外腔半导体激光器

为了提高1.5μm波段激光器的频率稳定性,利用乙炔分子饱和吸收稳频,设计了一种稳频的光纤光栅外腔半导体激光器。其通过步进电机对光纤光栅进行拉伸调节波长,实现了激光频率调谐。结果表明,所研制的激光器拥有较高的频率稳定度。     

Wavelength stabilisation of 1.5 ?m GaInAsP/InP bundle-integrated-guide distributed-Bragg-reflector (BIG-DBR) lasers integrated with wavelength tuning region

The temperature dependence of the lasing wavelength was stabilised in wavelength-tunable 1.5 ?m GaInAsP/InP bundle-integrated-guide distributed-Bragg-reflector (BIG-DBR)-type dynamic-single-mode (DSM) lasers. The lasing wavelength was controlled to maintain a fixed wavelength over a temperature range of 40 deg C.