Energy‑efcient integrated silicon optical phased array

An optical phased array(OPA)is a promising non-mechanical technique for beam steering in solid-state light detection and ranging systems.The performance of the OPA largely depends on the phase shifter,which afects power consumption,insertion loss,modulation speed,and footprint.However,for a thermo-optic phase shifter,achieving good performance in all aspects is challenging due to trade-ofs among these aspects.In this work,we propose and demonstrate two types of energy-efcient optical phase shifters that overcome these trade-ofs and achieve a well-balanced performance in all aspects.Additionally,the proposed round-spiral phase shifter is robust in fabrication and fully compatible with deep ultraviolet(DUV)processes,making it an ideal building block for large-scale photonic integrated circuits(PICs).Using the high-performance phase shifter,we propose a periodic OPA with low power consumption,whose maximum electric power consumption within the feld of view is only 0.33 W.Moreover,we designed Gaussian power distribution in both the azimuthal(ψ)and polar(θ)directions and experimentally achieved a large sidelobe suppression ratio of 15.1 and 25 dB,respectively.

Bidirectional high sidelobe suppression silicon optical phased array

An optical phased array(OPA),the most promising non-mechanical beam steering technique,has great potential for solid-state light detection and ranging systems,holographic imaging,and free-space optical communications.A high quality beam with low sidelobes is crucial for long-distance free-space transmission and detection.However,most previously reported OPAs suffer from high sidelobe levels,and few efforts are devoted to reducing sidelobe levels in both azimuthal(φ)and polar(θ)directions.To solve this issue,we propose a Y-splitter-assisted cascaded coupling scheme to realize Gaussian power distribution in the azimuthal direction,which overcomes the bottleneck in the conventional cascaded coupling scheme and significantly increases the sidelobe suppression ratio(SLSR)in theφdirection from 20 to 66 dB in theory for a 120-channel OPA.Moreover,we designed an apodized grating emitter to realize Gaussian power distribution in the polar direction to increase the SLSR.Based on both designs,we experimentally demonstrated a 120-channel OPA with dual-Gaussian power distribution in bothφandθdirections.The SLSRs inφandθdirections are measured to be 15.1 d B and 25 dB,respectively.Furthermore,we steer the beam to the maximum field of view of 25°×13.2°with a periodic 2λpitch(3.1μm).The maximum total power consumption is only 0.332 W with a thermo-optic efficiency of 2.7 m W∕π.