Low frequency Raman scattering for high resolution low temperature optical fiber sensors

Raman distributed optical fiber temperature sensors are based on the intensity ratio of the anti-Stokes to the Stokes Raman band at 440 cm−1 of silica. In this paper we predict that the sensitivity of the Raman measurements for low temperatures can be improved by considering the Boson peak in the low frequency Raman scattering domain at 60 cm−1. In this way Raman temperature sensors can be performed down to cryogenic temperatures. It is further shown that the Boson peak is less dependent than the 440 cm−1 band to the polarization of light. For the usual excitation at 1550 nm the anti-Stokes Boson peak at 1536 nm is in the low loss transmission window of the silica fibers.