RAMAN-SCATTERING CROSS-SECTION AND NONLINEAR-OPTICAL RESPONSE OF LEADBORATE GLASSES

Lead berate glasses in the system xPbO .(10-x)B2O3(5 less than or equa l to x less than or equal to 9) have been studied by Raman scattering and Z-scan non-linear optical measurements. It is found that both Rama n scattering cross-section and non-linear refractive index, n(2), of g lasses increase significantly with increasing lead oxide content. The increase in Raman cross-section is dominated by an increase in the tow -frequency Raman scattering. The results indicate that both electronic and nuclear responses contribute to the observed optical non-linearit y which is further enhanced by two-photon resonance effects for glasse s with x greater than or equal to 80 mol%. The nuclear response is att ributed to low-frequency vibrational modes and the electronic response to highly polarizable lead cations in the glass matrix.