Dual Polarization and Bi-Directional Silicon-Photonic Optical Phased Array With Large Scanning Range

Abstract

We propose a large scanning range silicon optical phased array (OPA), which is polarization multiplexed and bidirectional with only one waveguide grating antenna array. Mach-Zehnder interferometers (MZIs) and polarization splitterrotator (PSR) are utilized to select the polarization states and propagation directions of the input light to the waveguide grating emitter array. By optimizing the parameters of the waveguide grating, the longitudinal far-field steering range is increased by four times compared to that of the conventional ones among the same wavelength range. The simulation results show that the 54.5° longitudinal scanning range could be realized with the tuning wavelength ranging from 1500 nm to 1600 nm. The high wavelength tuning efficiency is up to 0.545 °/nm. The beam steering range in the lateral direction is 77.8° via phase tuning.

Beam Steering Technology of Optical Phased Array Based on Silicon Photonic Integrated Chip

“…By reasonably designing the cross-sectional size of the waveguide, the difference in effective refractive indices between TE 0 mode and TM 0 mode in the waveguide is reduced, and ultimately achieves a longitudinal continuous scanning of 28.2° within the bandwidth of 1500–1600 nm. In 2022, Zhao et al added an optical switch in front of the OPA to control the forward/reverse input of light in the array [ 46 ]. Combined with the polarization multiplexing scheme described in [ 45 ], a continuous scanning range of 54.5° was achieved on the 340 nm SOI platform.…”

Photonic Integrated Circuits for an Optical Phased Array

“…These designs can be divided into two categories. The first category involves ensuring that the grating coupler functions effectively as multiple normal grating couplers, which have a uniform periodicity and duty cycle [50][51][52][53]. By spatially combining two normal grating couplers, a compound period grating coupler can be formed, which can generate two emitting beams, resulting in a steering range of approximately 26 • over a 100 nm wavelength range, which is roughly double the original steering capability [50].…”

“…By utilizing three different modes and designing nanogratings that create spatial fluctuation specifically for each mode, the steering range can be roughly tripled to approximately 40 • [52]. Additionally, by incorporating a switch and two polarization rotators before the grating coupler, both directions (forward and backward) and both polarizations (TE and TM) can be selected, resulting in a steering range that is roughly four times greater, reaching 54.5 • over a 100 nm wavelength range [53]. The second category of attempts to mitigate the restriction of the steering range involves manipulating the effective index (n eff ) by incorporating a photonic crystal waveguide [54][55][56][57].…”

All-Solid-State Beam Steering via Integrated Optical Phased Array Technology

“…Our group also proposed a dual polarization and bi-directional OPA, as shown in Figure 9, to further increase the FOV in the wavelength dimension. The wavelength tuning efficiency was further doubled to 0.55 °/nm, with only one waveguide grating antenna array [85]. Aside from the beam steering angle, beam divergence is also another important performance of the OPA.…”