With the development of automatic driving and remote sensing technology, light detection and ranging (LIDAR) has attracted more attentions. The optical phased arrays in silicon photonics have became one of the major solutions of LIDAR due to its low material cost, high integration, and compatibility with CMOS technology. However, most of the optical antennas used by LIDAR are directly etched second-order gratings on the array waveguides, which makes the emission efficiency very low, and a large part of the energy is wasted by the side lobes and grating lobes. Therefore, improving the antenna emission efficiency and its energy utilization has become the key solution to improve the performance of phased-array LIDAR systems.

In this paper, a novel optical antenna for integrated LIDAR with optical phased arrays is proposed and simulated. The high contrast grating (HCG) structure is used to achieve extremely efficient emission. The basic structure of the optical antenna consists of a 220nm Si plane waveguide at the top-Si layer of SOI substrate, a 110nm SiO₂ gap layer, and a 463nm Polysilicon layer. The HCG period is 1.228μm and duty cycle is 0.388, and it is etched at the Polysilicon layer.

The proposed optical antenna has improved emission efficiency, energy utilization, and achievable scanning range. It is possible to increase emission efficiency significantly by the resonance properties of the HCG. 81.6% emission efficiency of the optical antenna is obtained with background suppression of 28.4 dB at 1550 nm. Moreover, the optical antenna can achieve more than 50% emission efficiency in the wavelength range of 1484 nm to 1609 nm. ±34.82°×18.99° scanning range was realized in lateral direction and longitudinal direction, respectively, by changing the phase difference between adjacent waveguides and the wavelength from 1480 nm to 1580 nm. In lateral direction, the scanning range achieved by the proposed optical antenna is 1.54 times larger than that of an arrayed waveguide grating with the same size. In longitudinal direction, the proposed optical antenna can achieve substantially the same scanning range as the arrayed waveguide grating.