940 nm VCSEL高折射率对比度亚波长光栅反射镜的设计

Design of high refractive index contrast subwavelength grating reflector for 940 nm VCSEL

研究了一种940 nm GaAs基VCSEL的高折射率对比度亚波长光栅反射镜(HCG),采用GaAs/AlOx光栅结构,讨论了TE偏振时光栅结构中各参数对反射光谱的作用规律,分析TE、TM不同偏振时反射镜的结构特点,及形貌误差对高反射带的影响。设计的TE-HCG的高反射带中心为940 nm,在0.888~0.985μm波长范围内,TE波反射率大于99.5%,TM波反射率低于90%,高反射带宽97 nm,Δλ/λ_(0)>10%。该反射镜可以与VCSEL采用一次性外延生长技术制作,且具有结构简单,制作容差大,且偏振稳定的优势,不仅有利于改善器件性能,且大大降低VCSEL的制作难度和成本。

A high-refractive-index contrast subwavelength grating(HCG)for 940 nm GaAs-based VCSEL is reported.The reflector is composed of GaAs and AlOx.The effects of the grating parameters of TE-HCG on refractivity are discussed in detail.And the structural characteristics of TE-HCG and TM-HCG are analyzed,especially the influence of their topography errors on the high reflection band.The 940 nm TE-HCG has a large reflection bandwidth of up to 97 nm with its reflectivity for TE incident light more than 99.5%,and the ratio of Ratio of high reflection band to central wavelength is more than 10%.But for TM incident light its reflectivity is less than 90%.It is worth mentioning that the VCSEL with such a TE-HCG can be prepared by one-time epitaxial growth technology,which helps to improve the performance of the device.Furthermore,it greatly reduces the manufacturing difficulty and cost of a VCSEL.