Study on the convex dual-blazed grating

The high diffraction efficiency of the convex blazed gratings cannot be realized in the broadband. Therefore, we have designed the convex dual-blazed grating to realize higher and uniform diffraction efficiency in the wavelength from 0.4 μm to 2.5 μm. The diffraction efficiency of the convex dual-blazed grating is investigated by using rigorous coupled wave analysis. The results show: when the two blaze angles of the convex dual-blazed grating, one within the range from 2.7 degree to 3.4 degree and the other one within the range from 8 degree to 9 degree respectively, the first-order diffraction efficiency is more than 25 percent at the visible-near infrared band. The convex dual-blazed grating with the period of 5μm in the center will be fabricated by holographic lithography-segmented ion beam etching in late 2017.