Absorption coefficient and Raman gain in CVD diamond as functions of pump wavelength: Towards efficient diamond Raman lasers

The design of diamond Raman lasers is contingent upon the wavelength dependence of the absorption coefficient and the Raman gain coefficient in chemical vapour deposition (CVD) grown diamond. Optical absorption in CVD diamond results mainly from the presence of substitutional nitrogen. The absorption coefficient increases at shorter wavelengths and can be significant for diamonds with substitutional nitrogen concentrations of the order of a few hundred parts per billion (ppb). This absorption should be taken into account during measurements of the Raman gain. The dependence of the absorption and Raman gain coefficients on the pump wavelength will determine the useful spectral range for diamond Raman lasers.