Image sensor for spectral-domain optical coherence tomography on a chip

Abstract

This Letter presents a global shutter image sensor based on PINphotodiodes intended to be used for optical coherence tomography(OCT) in the spectral domain, where the light is brought to the photo-diodes via optical waveguides monolithically integrated on top of elec-tronics in a photonic layer. Photodiodes are optimised to have the peakresponsivity in the wavelength range between 800 and 900 nm, whilethe main features of electronics are high signal-to-noise ratio, highframe rate, low-power consumption and low noise. The sensor isdesigned using 0.35 µm high voltage CMOS and employing lowdoped epitaxial starting material in order to improve the detector effi-ciency by enabling fully depleted photodiodes and lowering the cross-talk. Image sensor parameters are obtained using the photon-transfercurve method and compared with commercial cameras for OCT.