Multi-channel lock-in based differential front-end for broadband Raman spectroscopy

In Broadband Stimulated Raman Spectroscopy, the intrinsic limit given by the laser shot noise is seldom reached due to the electronic noise of the front-end amplifier and the intensity fluctuations of the laser source. In this paper we present a low-noise multi-channel acquisition system, with an integration-oriented design, able to compensate the common-mode fluctuations of the laser output power with the pseudo-differential structure and reach a sensitivity better than 10 ppm thanks to the lock-in technique.