Design Of 2μm Subwavelength Grating With Wide Broadband And High Reflectivity

In recent years,with the growing demand for semiconductor lasers,VCSEL with excellent performance and large scale integration has become a research hotspot.Developing a simple cavity reflector with high reflectivity and easy fabrication on large scale to replace the traditional Prague reflector（DBRs）has become an urgent problem in the new VCSEL.In this paper,three kinds（mirror with a pair of DBRs,mirror with SiO₂ grating layer,mirror containing a pair of DBRs and SiO₂ grating layer）of TM mode subwavelength grating mirrors with different structures are designed and analyzed with the Rigorous Coupled Wave Analysis.The mirrors exhibit polarization and large fabrication tolerance while having high reflectivity and wide bandwidth（reflectivity R>99.9%,bandwidth width over 180 nm）in the 2μm band,and the related characteristics of the mirror are briefly analyzed by the Effective medium theory.The results show that the mirror with a pair of DBRs and SiO₂ grating layer has a bandwidth up to 310nm with a reflectivity R>99.9%,and a very large tolerance can make it suitable for large-scale fabrication integration on VCSELs.