DETERMINATION OF THE RAMAN GAIN COEFFICIENT IN LEUCOSAPPHIRE

An experimental investigation was made of stimulated Raman scattering in leucosapphire (alpha-Al2O3) pumped at the wavelength lambda = 532 n n by pulses of tau = 30 ps duration (the second harmonic of an Nd3+:Y( 3)A1(5)O(12) laser). The Raman gain coefficient was determined for the first vibrational Stokes component with the wavelength lambda = 544 n m, corresponding to a Stokes shift of 419 cm(-1). This gain coefficien t varied from 2.5 x 10(-10) to 4.6 x 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 co nversion efficiency was eta = 1% when the pump intensity was 100 GW cm (-2).