|Abstract:In order to reduce imaging spectrometer’s polarization sensitivity and improve its quantitative measurement accuracy of target’s spectral radiance, a transmission polarization-independent two-dimensional binary blazed grating was proposed. It consists of periodical groove units in both orthogonal directions and there contains 7 sub-periods within one groove unit. Duty cycles of sub-periods are independent in two orthogonal directions, so that the effective index of both TE and TM polarizations can be modulated simultaneously, and the grating’s polarization property can be optimized. Through extending the effective medium theory to the two-dimensional pattern, a two-dimensional binary blazed grating with polarization-independent high efficiency on fused silica substrate was designed for wavelength range from 0.6 to 0.8μm. The grating periods in two orthogonal directions are 3.31μm and 0.473μm, respectively. Simulation results show that, for normal incident light, diffraction efficiencies of TE and TM polarizations at reference wavelength 0.7μm are 78.4% and 78.3%, respectively. Within wavelength range from 0.6 to 0.8μm, diffraction efficiencies of TE and TM polarizations are both above 70% and the degree of polarization is below 2.6%. Compared with one-dimensional binary blazed grating, the two-dimensional grating has the advantages of high diffraction efficiency, low degree of polarization and easier manufacture. It is expected to be used in grating-type imaging spectrometers.