Toward Spectral-Domain Optical Coherence Tomography on a Chip

We present experimental results of a spectral-domain optical coherence tomography system based on an integrated optical spectrometer. A 195-channel arrayed-waveguide-grating (AWG) spectrometer with 0.4-nm channel spacing centered at 1300 nm and a 125-channel AWG with 0.16-nm channel spacing centered at 800 nm have been fabricated in silicon oxynitride waveguide technology. Interferometric distance measurements have been performed by launching light from a broadband source into a free-space Michelson interferometer, with its output coupled into the AWG. A maximum imaging depth of 1 mm and axial resolution of 25 and 20 μm in air are demonstrated for the 800- and 1300-nm ranges, respectively.