InP基长波长晶体管激光器(特邀)

InP Based Long Wavelength Transistor Lasers(Invited)

晶体管激光器同时具有激光器的光发射功能与晶体管的电流控制功能,表现出多种新颖的光电特性.相对于短波长GaAs基器件,InP基长波长晶体管激光器更适合于光纤通信系统应用因而具有重要研究价值.本文主要介绍发光波长在1.3μm与1.5μm的InP基长波长晶体管激光器的研究进展,对不同结构器件的特点及可用于提高器件性能的相关器件设计进行了分析和讨论.根据器件波导结构的不同目前已报道的边发射晶体管激光器主要包括浅脊、掩埋及深脊结构三种类型.浅脊晶体管激光器中有源量子阱材料被置于重掺杂基区材料之中,使得InP基晶体管激光器只能在低温工作.掩埋结构的InP基晶体管激光器采用npnp型InP电流阻挡层掩埋脊条型有源材料,制作工艺过于复杂,不利于降低器件成本.深脊晶体管激光器中量子阱有源区材料位于重掺杂基区材料之上,可同时减小掺杂杂质扩散及基区材料光吸收的不利影响,基于该结构实现了InP基1.5μm波段晶体管激光器室温连续电流工作.数值计算研究表明,在深脊晶体管激光器量子阱中进行n型掺杂及在其发射极波导中引入由反向pn结构成的电流限制通道均可以减少载流子向缺陷的扩散,进而减小缺陷的不利影响,提高器件性能.

A transistor lasers have functions of both light emission of a laser and current control of a transistor and has many novel opto-electronic properties.Compared with short wavelength GaAs based transistor lasers,InP based long wavelength transistor lasers are more suitable for optical fiber communication systems.In this paper,the research progress of InP based long wavelength transistor lasers with emission wavelengths of 1.3/1.5μm is introduced.The characteristics of long wavelength transistor lasers with different structures and the related device designs that can be used to improve the performance of the devices are discussed.Based on different waveguide structures,three types of edge emitting long wavelength transistor lasers have been reported up to now,which are shallow ridge,buried ridge and deep ridge transistor lasers,respectively.In the shallow ridge transistor lasers,multi-quantum wells are positioned in the p type doped base material.As a result,laser operation of an InP based shallow ridge transistor laser with 1.5μm wavelength has been realized only at low temperatures.In the buried ridge transistor lasers,AlGaInAs multi-quantum wells are burried with current blocking InP layers.The fabrication process of the device is complex,which leads to a high cost.In the deep ridge transistor lasers,because multi-quantum wells are inserted between the emitter and the base layers,both the diffusion of p type dopant into the multi-quantum wells and the optical absorption of the p type base material can be reduced noticeably.Room temperature operation of InP based deep ridge transistor laser with 1.5μm wavelength has been fabricated successfully.Numerical simulations show that by n type doping in the multiquantum wells or introducing a current confinement aperture in the emitter ridge,the effects of the nonradiative recombination centers can be reduced greatly.