Femtosecond laser written diamond waveguides: A step towards integrated photonics in the far infrared

A first demonstration and complete characterization of mid-infrared waveguides in single crystal diamond are reported. Waveguides were designed for 2.4 ?m and 8.6 ?m waveguiding, with their group velocity dispersion analyzed using femtosecond pulses at 2.4 ?m wavelength propagated through the waveguide and the bulk substrate. The total dispersion was found to be dominated by the bulk material rather than the waveguide, and was on the range of 275 fs/mm, demonstrating that femtosecond laser written modifications in diamond introduce negligible perturbations to the pristine material.