Study On Preparation Process Of GaSb Based VCSEL

2-5?m mid-infrared vertical cavity surface emitting laser?VCSEL?,featured with advantages of low consumption,small divergence angle,no astigmatism circular spot,high modulation bandwidth,wavelength stability,low cost,and high density packaging,is an ideal light source of for the molecular spectrum measurement,biochemical testing,laser radar and thermal imaging and other medical diagnosis and drug analysis.For example,in a TDLAS?tunable laser diode absorption spectroscopy test?system for monitoring polluting gases CO,CH4,NH3 and HF,the use of VCSEL as a light source will greatly reduce the complexity and cost of beam shaping and coupling encapsulation,and modulation rate of the system with small size can reach several tens of Gbit/s.So VCSEL has been considered to be the best alternative device of DFB?distributed feedback?laser in the future.GaSb material is suitable for development of 2-5?m VCSEL.In this paper,the performance of GaSb-based VCSEL is improved by replacing traditional DBR with high contrast sub-wavelength grating?HCG?.1.According to the working principle of VCSEL and the structural characteristics of the HCG,a TM polarized Sub-wavelength grating Mirror used in 2?m band is designed,The effects of parameters such as period,depth,duty cycle and low refractive index sublayer on the reflection characteristics of HCG are studied.The characteristics of GaSb-based VCSEL integrated with HCG are simulated,including the electric field intensity distribution,refractive index distribution and mode intensity distribution of light field in resonant cavity.2.Considering the structural characteristics of GaSb-based VCSEL integrated with HCG and the degradation of HCG characteristics caused by the integrated process,the preparation process of a GaSb-based HCG-VCSEL is optimized.Based on the above optimization,the layout design is completed.3.The preparation technology of sub-wavelength grating was studied experimentally.High quality SiO₂ thin films were prepared by plasma enhanced chemical vapor deposition?PECVD?.In order to obtain the required HCG mirror,the technology of holographic lithography,electron beam exposure and icp dry etching was studied,and the surface morphology was characterized by scanning electron microscope?SEM?.4.The fabrication of gasb-based VCSEL with high contrast sub-wavelength grating is investigated.The wet etching process of GaSb materials,accurate alignment process and electrode process are presented in detail.Etching morphology and rate were optimized by changing the composition and proportion of the etching solution.The method of ultra-violet lithography is used to realize the precise alignment process,and the electrode is realized by adopting the magnetron sputtering technology and the reverse process.Combining with the fabrication technology of HCG mirror,the device is fabricated,and the laser spectrum of the device is tested and analyzed.