Determination of the Raman gain coefficient in leucosapphire

Abstract

An experimental investigation was made of stimulated Raman scattering in leucosapphire (α-Al2O3) pumped at the wavelength λ = 532 nm by pulses of τ =30 ps duration (the second harmonic of an Nd3+ : Y3Al5O12 laser). The Raman gain coefficient was determined for the first vibrational Stokes component with the wavelength λ = 544 nm, corresponding to a Stokes shift of 419 cm-1. This gain coefficient varied from 2.5 × 10-10 to 4.6 × 10-10 cm W-1, depending on the relative orientation of the leucosapphire crystal axes relative to the plane of polarisation and to the axis of the pump beam. The energy conversion efficiency was η =1% when the pump intensity was 100 GW cm-2.