Stimulated Raman scattering of light in suspension of diamond microparticles in ethanol and in water

The spectra of stimulated Raman scattering of light in ethanol and in water suspensions containing diamond microparticles with sizes 0.2-0.3 μm were investigated. An excitation radiation source was a pulsed ruby laser with a generation wavelength λ₀ = 694.3 nm, a pulse duration τ_p ≈ 20 ns, a maximum beam energy of E_max = 0.6 J, a spectral width Δν = 0.015 cm^-1, and a beam divergence 3.5·10^-4 rad. For the first time, the observation of stimulated Raman scattering of light at a boson peak in suspension of diamonds microcrystals with close sizes (0.2-0.3 μm) in a liquid is reported. The corresponding spectra were recorded using a Fabry-Perot interferometer. In this case, the frequency shift of the stimulated Stokes Raman scattering depended on the size of the diamond microparticles introduced into the liquid and amounted to ~1 cm^-1. In addition, stimulated Raman scattering by a fundamental optical mode with a frequency shift ν = 1331 cm^-1 was observed. In this case, the Raman spectra were recorded using a small-sized spectrometer with a multi-element receiver, detecting radiation in the range of 200-1000 nm. At a sufficiently high intensity of the exciting radiation, the Stokes and anti-Stokes satellites were simultaneously present in the spectrum of stimulated Raman scattering. The obtained results on stimulated scattering of diamond microparticles in liquids are of interest for estimating the sizes of microcrystals from scattering spectra at a boson peak, as well as for creating a frequency comb of emitters based on stimulated Raman scattering with a large frequency shift.