Two-dimensional silicon optical phased array with large field of view

Hybrid integrated thin-film lithium niobate-silicon nitride electro-optical phased array incorporating silicon nitride grating antenna for two-dimensional beam steering

This study proposes a solid-state two-dimensional beam-steering device based on an electro-optical phased array (EOPA) in thin-film lithium niobate (TFLN) and silicon nitride (SiN) hybrid platforms, thereby eliminating the requirement for the direct etching of TFLN. Electro-optic (EO) phase modulator array comprises cascaded multimode interference couplers with an SiN strip-loaded TFLN configuration, which is designed and fabricated via i-line photolithography. Each EO modulator element with an interaction region length of 1.56 cm consumed a minimum power of 3.2 pJ/π under a half-wave voltage of 3.64 V and had an estimated modulation speed of 1.2 GHz. Subsequently, an SiN dispersive antenna with a waveguide grating was tethered to the modulator array to form an EOPA, facilitating the out-of-plane radiation of highly defined near-infrared beams. A prepared EOPA utilized EO phase control and wavelength tuning near 1550 nm to achieve a field-of-view of 22° × 5° in the horizontal and vertical directions. The proposed hybrid integrated platform can potentially facilitate low-power and high-speed beam steering.

Polarization multiplexing silicon photonic optical phased array with a wide scanning range

We propose and experimentally demonstrate a polarization multiplexed silicon optical phased array (OPA) with a wide scanning range. The two polarization states share the same power splitter tree and the phase shifter array. A polarization switch is introduced in front of the power splitter tree to manipulate the polarization state of the light in OPA. Through a polarization splitter-rotator (PSR), the light of two polarization states propagates into the superlattice grating antenna array. The wavelength tuning efficiency could be doubled by optimizing the parameters of the waveguide grating. We demonstrate the scheme on the commonly used 220 nm silicon-on-insulator (SOI) platform. Experimental results indicate that the 24.8° vertical scanning range could be realized with a high wavelength tuning efficiency of 0.31°/nm. The measured field of view (FOV) is 24.8 × 60°.

Design of Monolithic 2D Optical Phased Arrays Heterogeneously Integrated with On-Chip Laser Arrays Based on SOI Photonic Platform

In this work, heterogeneous integration of both two-dimensional (2D) optical phased arrays (OPAs) and on-chip laser arrays based on a silicon photonic platform is proposed. The tunable multi-quantum-well (MQW) laser arrays, active switching/shifting arrays, and grating antenna arrays are used in the OPA module to realize 2D spatial beam scanning. The 2D OPA chip is composed of four main parts: (1) tunable MQW laser array emitting light signals in the range of 1480-1600 nm wavelengths; (2) electro-optic (EO) switch array for selecting the desired signal light from the on-chip laser array; (3) EO phase-shifter array for holding a fixed phase difference for the uniform amplitude of specific optical signal; and (4) Bragg waveguide grating antenna array for controlling beamforming. By optimizing the overall performances of the 2D OPA chip, a large steering range of 88.4° × 18° is realized by tuning both the phase and the wavelength for each antenna. In contrast to the traditional thermo-optic LIDAR chip with an external light source, the overall footprint of the 2D OPA chip can be limited to 8 mm × 3 mm, and the modulation rate can be 2.5 ps. The ultra-compact 2D OPA assembling with on-chip tunable laser arrays using hybrid integration could result in the application of a high-density, high-speed, and high-precision lidar system in the future.