Compact Raman spectrometer system for low frequency spectroscopy

We report low frequency Stokes and anti-Stokes Raman spectra resolving frequency shifts down to 15 cm(-1) using a standard commercial Raman spectrometer with ultra-narrow band notch filters. The ultra-narrow band notch filters were fabricated holographically in a glass material with optical densities ranging from 4 to 6 per notch filter at the standard Raman laser lines of 488 nm, 532 nm, 633 nm and 785 nm. The notch filters have greater than 80% transmission at 15cm(-1) away from the laser line. This simple notch filter-based system provides high performance low frequency Raman spectroscopy as a low cost alternative to bulky and expensive triple spectrometer Raman systems. Optical Density