Supercontinuum generation in bulk diamond — Experiment and the model

Diamond is known from its strong single and narrow Raman line at 1332 cm^-1. Our goal was to examine if the Raman response will noticeable influence the process of supercontinuum generation in diamond. We thus study experimentally the spectrum of the supercontinuum generated in a bulk diamond crystal as a function of the input energy. The 1 kHz regenerative amplifier was used as a source for 800 nm wavelength, 45 fs long input pulses. The advancing broadening of the blue side of supercontinuums spectrum is observed for energies below 26 μJ. The blue edge of supercontinuum has been found to be static for higher energies. The edge was found to be 615 nm. This limit is much higher than in case of commonly used shappire or CaF₂. It makes diamond not favourable as a material for supercontinuum generation for spectroscopic purposes in the visible light. The existence of the edge can be explained [1] by a 5-photon absorption over the band-gap. For energies over 31 μJ patterns characteristic for pulse splitting have been observed.