混合应变多量子阱实现折射率变化低偏振相关的理论分析

Theoretical Analysis on Polarization Dependence of Refractive Index Change of Mixed Strain Multiple Quantum Well

考虑温度变化和载流子注入阱间分布不均匀性,给出求解量子阱材料折射率变化的理论分析模型。分析了量子阱应变量大小、阱宽、垒区材料组分和注入载流子浓度对TE模和TM模折射率变化的影响。设计出折射率变化低偏振相关的混合应变多量子阱结构,在0~40℃的温度范围,其折射率变化量在1 530~1 570nm波长范围内具有较大数值（6×10^-3）,且具有低的偏振相关性;当载流子浓度从1×10^24 m-3增大到3×10^24 m-3时,其折射率变化量在增大的同时,仍可在一定温度下保持低偏振相关。

Carrier-induced refractive index change is the work mechanism of many optical communication devices,such as optical switches,wavelength converters.It is also an important parameter of semiconductor lasers and semiconductor optical amplifiers.When injected carrier concentration and ambient temperature change,the operating temperature of active region of these devices changes too.In optical fiber communications,several factors influence the polarization states of signal light randomly.To acquire good operating performances in actual applications,it is necessary to make the refractive index change insensitive to the polarization state when active region temperature changes.In this paper,the theoretical model of solving refractive index change of quantum well is given out,which takes into account the temperature variation as well as the nonuniform distribution of injected carrier in multiple quantum well（MQW）.The influences of strain,well width,barrier material component and injected carrier concentration on the refractive index changes of TE mode and TM mode in quantum well are analyzed.A mixed strain MQW with polarization insensitivity of refractive index change has been designed.The refractive index change of this MQW has a large value（6×10-3）when wavelength varies from 1 530 nm to 1 570 nm as temperature varies from 0 ℃to 40 ℃,meanwhile it is insensitive to the polarization state.When the injected carrier concentration increases from 1×1024 m-3 to 3×1024 m-3,the refractive index change not only increases but also keeps low polarization dependence in a certain temperature.