Alloy composition dependence of 1.55 μm GaP_1−xSb_x/GaP_0.2Sb_0.8Bragg reflector reflectivity under normal and oblique incidence

Abstract

Reflectivity spectra of a 1.55 μm GaP1−x Sbx/GaP0.2 Sb0.8 distributed Bragg reflector (DBR) are calculated for various antimony compositions x in the range 0 ≤x≤0.7 by means of the stratified medium theory under matrix representation. Both normal and oblique incidence cases are examined. The maximum of reflectivity is found to be improved by increasing the number of pairs in the stack. The DBR bandwidth is controlled by the refractive index difference between materials constituting the DBR. On going from small to high incidence angle values, the reflectivity spectrum is shifted towards smaller wavelengths. The present results are consistent with the overall picture of DBRs as reported in the literature and show the capability of our system to operate as an efficient DBR for the most important telecommunication wavelength of 1.55 μm.