Coherent modem-enabled spread-spectrum time-domain diffuse optical spectroscopy.

We present a spread-spectrum time-domain diffuse optical spectroscopy (TD DOS) system utilizing a commercially available dual-polarization coherent optical modem operating at a wavelength of 1547.7 nm. The modem features a sampling rate of 114.6 GSa/s, enabling a temporal resolution of 17.5 ps. Our findings demonstrate that for low received optical powers (< -72 dBm), the scattering and absorption parameters of two studied tissue phantoms can be estimated with less than 12% fitting error within an exposure time of under 6 ms.