High-efficiency, low-crosstalk multiplexed volume Bragg grating for non-mechanical angular magnification

The demand for compact transmitting volume Bragg gratings (TVBGs) for non-mechanical angular magnification is growing quickly in the industrial and defense areas. However, channel crosstalk limits the angular width and diffraction efficiency of multiplexed TVBGs. In this work, a crosstalk criterion is first proposed to evaluate the channel crosstalk quantitatively. Based on this criterion, for ±45° non-mechanical angular magnification, 12-channel high-efficiency low-crosstalk TVBGs are achieved by reducing the half-width at first zero (HWFZ) of the angular selectivity curve. Compared to the unoptimized scheme, the measured average relative diffraction efficiency of all optimized TVBGs reach 92 %, and the maximum HWFZ is reduced from 12.3496 to 1.7628 mrad. Our approach paves the way to develop high-performance multiplexed devices.