Very Low Frequency Stokes and Anti‐Stokes Raman Spectra Accessible with a Single Multichannel Spectrograph and Volume Bragg Grating Optical Filters

Multichannel measurement of Raman bands with frequencies very close to the excitation line has traditionally been possible with the use of triple monochromator systems. These systems are very flexible, but they can be complex to use, large, low in throughput, and expensive. We have recently demonstrated the use of a single monochromator Raman system where the Rayleigh filtering elements are made of Volume Bragg Gratings (VBGs); such a system enabled recording of Stokes and antiStokes modes with frequencies less than 10 cm.