SRS in di‐glycine nitrate (NH2CH2COOH)2 · HNO3 crystals: Observation of high‐gain many‐phonon nonlinear interactions

Abstract

AbstractEfficient high‐gain many‐phonon steady‐state stimulated Raman scattering (SRS) was excited in the novel χ(3)‐active organic crystal of di‐glycine nitrate (DGN), (NH2CH2COOH)2 · HNO3, at room temperature under picosecond laser pumping in the visible and near‐IR regions. Besides high‐order Stokes and anti‐Stokes (comb) generation in this centrosymmetric crystal, several cascaded and cross‐cascaded χ(3) ↔ χ(3) nonlinear photon–phonon interactions were observed. The recorded Raman‐induced lasing wavelengths were identified and attributed to the SRS‐promoting optical vibration modes ωSRS1 ≈ 1058 cm−1, ωSRS2 ≈ 2985 cm−1, ωSRS3 ≈ 895 cm−1, and ωSRS4 ≈ 3000 cm−1. The measured large Raman frequency shifts (≈3000 cm−1) and estimated moderately high steady‐state Raman gain coefficients ($g_{{\rm ssR}}^{{\rm St}_{1} } $ ≥ 6.5 cm · GW−1) make this DGN crystal attractive for a number of new applications in modern laser physics and nonlinear optics.