IQ Photonic Receiver for Coherent Imaging With a Scalable Aperture
Silicon photonics (SiP) integrated coherent image sensors offer higher sensitivity and improved range-resolution-product compared to direct detection image sensors such as CCD and CMOS devices. Previous generations of SiP coherent imagers suffer from relative optical phase fluctuations between the signal and reference paths, which results in random phase and amplitude fluctuations in the output signal. This limitation negatively impacts the SNR and signal acquisition times. Here, we present a coherent imager system that suppresses the optical carrier signal and removes non-idealities from the relative optical path using a photonic in-phase (I) and quadrature (Q) receiver via a 90° hybrid detector. Furthermore, we incorporate row-column read-out and row-column addressing schemes to address the electro-optical interconnect density challenge. Our novel row-column read-out architecture for the sensor array requires only 2N interconnects for N² sensors. An 8×8 IQ sensor array is presented as a proof-of-concept demonstration with 1.2×10⁻⁵ resolution over range accuracy. Free-space FMCW ranging with 250μm resolution at 1 m distance has been demonstrated using this sensor array.
© 2021 The Author(s). This work is licensed under a Creative Commons Attribution 4.0 License. Received 21 July 2021; revised 10 September 2021; accepted 11 September 2021. Date of publication 17 September 2021; date of current version 10 December 2021. The authors would like to acknowledge Behrooz Abiri, Parham Porsandeh Khial, and Samir V. Nooshabadi for their valuable input and discussions
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