Demonstration of Two-Dimensional Beam Steering through Wavelength Tuning with One-Dimensional Silicon Optical Phased Array

Abstract

We demonstrate two-dimensional beam steering through wavelength control using a one-dimensional optical phased array (OPA) in which a path difference is built up in each channel to allocate a phase delay sequentially. Prior to the beam steering through wavelength tuning, phase initialization was performed to form a single beam using electro-optic p-i-n phase shifters to compensate for the phase error due to fabrication imperfections. With a 79.6 μm path difference in the phase-feeding lines and a 2 μm pitch in the grating radiators, we achieved a continuous transversal steering of about 46° through a wavelength tuning of about 7 nm. By extending the wavelength tuning range to 90 nm, longitudinal steering was attained near 13° with a discrete interval of about 1°. The beam was maintained during full two-dimensional steering and experienced only a small degree of degradation in the beam divergences and in the side lobe level. We analyzed the parameters to be able to induce the degradation of beam quality considering the fabrication errors of the geometric parameters of the OPA. The results indicated that the scanning scheme employing wavelength tuning after initialization with phase shifters can greatly reduce the realignment process of the beam pattern, even in the presence of some effective index perturbation during the fabrication.

Photonic Integrated Circuits for an Optical Phased Array

“…Achieving 2-D beam steering with only one degree of freedom is a significant challenge in passive OPAs. However, this issue can be addressed by leveraging the interference that can occur in multiple orders [48,[104][105][106]. This solution involves implementing relatively slower beam steering in one direction (θ), which can be achieved using waveguide grating couplers [48,104,105] or short delay lines across channels [106].…”

“…However, this issue can be addressed by leveraging the interference that can occur in multiple orders [48,[104][105][106]. This solution involves implementing relatively slower beam steering in one direction (θ), which can be achieved using waveguide grating couplers [48,104,105] or short delay lines across channels [106]. In contrast, much faster beam steering must be implemented in the other direction (ψ), which can be achieved using longer delay lines across the channels.…”

Intensive and Efficient Design of a Two-dimensional 8 × 8 Silicon-Based Optical Phased Array Transceiver

“…At the same time, the efficient compatibility of silicon on insulator (SOI) platforms and complementary metal oxide semiconductor (COMS) technology makes silicon photonic technology conducive to large-scale integration [11]. Therefore, the OPA based on a silicon photonic platform has become a research hotspot [12][13][14][15][16][17].…”