High-sensitivity frequency modulation CARS with a compact and fast tunable fiber-based light source

Frequency modulation (FM) coherent anti-Stokes Raman scattering (CARS) is presented, using a compact as well as fast and widely tunable fiber-based light source. With this light source, Raman resonances between 700 cm(-1) and 3200 cm(-1) can be addressed via wavelength tuning within only 5 ms, which allows forFMCARS measurements with frame-to-frame wavelength switching. Moreover, the functionality for high-sensitivity FM CARS measurements was integrated by means of fiber optics to keep a stable and reliable operation. The light source accomplishedFMCARS measurements with a 40 times enhanced sensitivity at a lock-in amplifier (LIA) bandwidth of 1 Hz. For fast imaging with frame-to-frame wavelength switching at a LIA band-width of 1 MHz, an 18-fold contrast enhancement could be verified, making this light source ideal for routine and out-of-lab FM CARSmeasurements for medical diagnostics or environmental sensing. (C) 2021 Optical Society of America

Automated summary

The technology utilizes a compact and fast tunable fiber-based light source for frequency modulation coherent anti-Stokes Raman scattering (CARS). With wavelength tuning, Raman resonances between 700 cm(-1) and 3200 cm(-1) can be addressed within 5 ms, allowing for frame-to-frame wavelength switching for FMCARS measurements. Integration of high-sensitivity functionality via fiber optics enables a 40 times enhanced sensitivity at a lock-in amplifier bandwidth.