Multi-Line Selective Optical Phased Array With Improved Uniformity of Radiated Beam Patterns

Abstract

We demonstrate a four-line selective optical phased array (FLS-OPA) with improved uniformity of radiated beam patterns. The FLS-OPA contains four basic OPA units, which are divided into two symmetric groups with the opposite incident directions of lights. In each group, the grating periods of the OPA units are set to 630 nm and 650 nm, respectively. Besides, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times 4$ </tex-math></inline-formula> thermo-optical switch is used to select an OPA unit out of four as the beam emitting unit. Therefore, four different emitting angles in the vertical direction can be realized by only two grating periods with a fixed wavelength. By tuning the wavelength from 1530 nm to 1635 nm and switching the OPA units, the FLS-OPA achieves a scanning range of 34.2° in the vertical direction, and the corresponding tuning efficiency is 0.33°/nm. In addition, the beam steering range in the horizontal direction is 21.4°. Thus, the overall field of view is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$21.4^{\circ } \times 34.2^{\circ }$ </tex-math></inline-formula> . Moreover, the symmetrical arrangement of the OPA units can improve the uniformity of the radiated beam patterns in the vertical direction.