Time-domain diffuse optical spectroscopy up to 1700 nm using an InGaAs/InP Single-Photon Avalanche Diode

Time domain diffuse optical spectroscopy provides the absorption and scattering properties of biological tissues and diffusive materials. Few measurements are available at discrete wavelengths beyond 1100 nm, and just one time-domain system continuously tuneable up to 1400 nm. We developed a time-domain system, based on a continuously tuneable supercontinuum pulsed source, and a custom InGaAs/InP Single-Photon Avalanche Diode. Operation was demonstrated in the 1100-1700 nm range with a spectral resolution of 15 nm, a temporal resolution of 150 ps and a background of 6000 counts/s. A first example of application on the optical characterization of collagen powder is given.