Generation of ultrashort optical pulses in the 10 fs regime using multicolor Raman sidebands in KTaO3.

We demonstrated Fourier synthesis of a new type of multiple coherent anti-Stokes Raman scatterings in KTaO(3) crystal. The signals with a wavelength range of 500-750 nm were generated by two femtosecond pulses whose frequency difference was set to be a two-phonon Raman frequency. Angle dispersion of the signals was compensated into one white-continuum beam by spherical mirrors and a prism. The spectral phase, measured by spectral phase interferometry for direct electric-field reconstruction, was compensated for by carefully aligning the angle and the position of the optical components so that 13 fs isolated pulses were generated. This result shows the robustness of our scheme to produce ultrashort optical pulses.