Generation of ultrashort optical pulses using multiple coherent anti-Stokes Raman scattering in a crystal at room temperature

We demonstrate Fourier synthesis of multiple coherent anti-Stokes Raman scattering signals in a $\mathrm{Li}\mathrm{Nb}{\mathrm{O}}_3$ crystal at room temperature. The signals up to the 20th order $(470–800\mathrm{nm})$ were generated by two crossing femtosecond Ti:sapphire laser pulses. Angle dispersion of the signals was compensated into one white-continuum beam by modifying a conventional $4f$ configuration. Spectral phase of the signal was measured by spectral phase interferometry for direct electric-field reconstruction. Isolated pulses with $25\mathrm{fs}$ duration at $1\mathrm{kHz}$ were generated only by appropriately aligning the angle-dispersion compensator. This result opens the possibility of the generation of subfemtosecond pulses in the visible region.