Abstract
We demonstrate a nonmechanical, on-chip optical beam-steering device using a photonic-crystal waveguide with a doubly periodic structure that repeats the increase and decrease of the hole diameter. We fabricated the device using a complementary metal-oxide-semiconductor process. We obtained a beam-deflection angle of 24° in the longitudinal direction, while maintaining a divergence angle of 0.3°. Four such waveguides were integrated, and one was selected by a Mach-Zehnder optical switch. We obtained lateral beam steering by placing a cylindrical lens above these waveguides. By combining the lateral and longitudinal beam steering, we were able to scan the collimated beam in two dimensions, with 80 × 4 resolution points.
Highlights
Compact light detection and ranging (LiDAR) devices can be used to measure and image the distances to surrounding objects for automatic driving, control of robots and drones, threedimensional (3D) mapping, and so on
On-chip optical beam-steering device using a photonic-crystal waveguide with a doubly periodic structure that repeats the increase and decrease of the hole diameter
The number of resolution points was 80 or more in the longitudinal direction and four in the lateral direction
Summary
Compact light detection and ranging (LiDAR) devices can be used to measure and image the distances to surrounding objects for automatic driving, control of robots and drones, threedimensional (3D) mapping, and so on. We have recently reported a photonic-crystal waveguide (PCW)—fabricated using a Siphotonics complementary metal–oxide–semiconductor (CMOS) process—that is coupled to a surface grating [10] This device guides a slow-light mode, radiates it into free space to form a fan-shaped beam, and acts like a nonmechanical deflector that achieves a large Δθ. By introducing the lattice shift s, low-dispersion slow light is obtained for ng ≈20 and Δλ ≈15 nm (λ = 1550–1565 nm) Including both ends of the transmission band, where ng decreases or increases markedly, light can propagate in the bandwidth Δλ = 27 nm (λ = 1550–1577 nm). When αrad is constant over the LSPCW, the radiation decays exponentially during propagation, due to the attenuation of the slow-light mode caused by the radiation itself and original waveguide loss αloss.
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