Noise Measurements and Noise Statistical Properties Investigations in a Stimulated Raman Scattering Microscope Based on Three Femtoseconds Laser Sources

To induce a Raman-active transition in a material, stimulated Raman scattering (SRS) spectroscopy/microscopy implementations typically rely on two pulsed laser sources. One of their limitations is that not all of the regions of Raman spectra can be investigated, so only some applications can be exploited. In this paper, the noise characterizations of a stimulated Raman scattering spectroscopy/microscopy implementation, based on the insertion of a third pulsed laser source, are provided. The merit of this system is that it is able to explore the large variety of SRS applications. In order to characterize our system, an investigation of different kinds of noises due to the laser sources and electronics sources was carried out. Firstly, the relative intensity noises of three femtosecond laser sources were measured. Secondly, noise characterizations of the detection system were carried out and our findings prove that our SRS microscope is shot noise-limited, demonstrating that the third laser source introduction is well suited and satisfies our purpose. Finally, the statistical properties of the overall image noises are analyzed and discussed.