Supercontinuum generation using Raman pumped optical cavity

Apparatus (10) for generating a supercontinuum (SC) in an optical cavity (18) by increasing the power of pump radiation having a first wavelength to cause broadening of lasing radiation having a second wavelength, i.e. the Stokes shifted wavelength, in the cavity to generate an output that is a SC. The first wavelength may be selected to cause stimulated Raman scattering in the cavity to generate the lasing radiation. The Raman amplification in the cavity may improve the efficiency of the SC generation because the input power, e.g. the power of the source used to pump the cavity, may be distributed over a range of wavelengths. In combination with other effects caused by non- linear optical properties of the cavity, the Raman amplification may generate a SC which exhibits a flat power profile across its broad spectral range.