An Effective 1µs/A-Scan, 8-Beam Space-Division Multiplexing Optical Coherence Tomography Using Photonic-IC Based Multi-Beam Generation and CMOS TIA Based Readout

Optical Coherence Tomography (OCT) is a non-invasive imaging modality that delivers micrometer-scale cross-sectional and volumetric views of biological tissue. This paper presents an 8-beam space-division multiplexing optical coherence tomography (SDM-OCT) system achieving an effective 1 µs/A-scan rate through a customized photonic integrated circuit (PIC) and CMOS transimpedance amplifier (TIA) readout architecture. The PIC generates eight laterally separated sample beams with ~3.5mm optical path offsets, mapping the output of each beam to a distinct frequency band that is ~70MHz apart. A 22nm SOI CMOS TIA capable of amplifying all the 8-beams achieves a digitally programmable 60–70 dB transimpedance gain, -3 dB bandwidth of 750 MHz, and input referred noise of 27 pA/√Hz. The SDM-OCT system achieves 10 µm axial and 22 µm lateral resolution, and in vivo imaging confirms an effective 8× improvement in volumetric acquisition speed compared to single-beam systems, significantly reducing motion artifacts.