Fig. 1. Design of HCG mirror structure

Fig. 2. Reflectivity spectrum of TE-HCG(grating parameters: Λ=781 nm, f=25.4%, H₁=166 nm, H₂=189 nm, H₃=170 nm)

Fig. 3. Reflectivity of TE-HCG varying with wavelength and incident angle. (a) Reflectivity of TE-HCG varying with wavelength (grating parameters: Λ=781 nm, H₁=166 nm, H₂=189 nm, H₃=170 nm, and the upper duty and lower duty of the grating ridge are f _upper=25.4% and f_lower=30.4%); (b) reflectivity of TE-HCG varying with incident angle for TE mode

Fig. 4. SEM images of HCG epitaxial structure and electron beam lithography. (a) SEM image of HCG epitaxial structure; (b) SEM image of electron beam lithography

Fig. 5. SEM of HCG cross section

Fig. 6. Reflectivity spectra of TE-HCG. (a) TE incident light; (b) TM incident light