Steady-State Raman Gain in Diamond as a Function of Pump Wavelength

The variation in the Raman gain coefficient in single-crystal diamond for pump wavelengths between 355 and 1450 nm is measured. Two techniques are used: a pump-probe approach giving an absolute measurement and a stimulated Raman oscillation threshold technique giving a relative measurement. Both approaches indicate that the Raman gain coefficient is a linear function of pump wavenumber. With the pump polarized along a <; 111 >; direction in the crystal, the Raman gain coefficient measured by the pump-probe technique is found to vary from 7.6 ± 0.8 for a pump wavelength of 1280 nm to 78 ± 8 cm/GW for a pump wavelength of 355 nm. With the established dependence of the Raman gain coefficient on the pump wavelength, the Raman gain coefficient can be estimated at any pump wavelength within the spectral range from 355 up to 1450 nm.