Simultaneous generation of spectrally distinct third harmonics in a photonic crystal fiber.

By coupling femtosecond pulses at lambda - 1.55mum in a short length (Z - 95 cm) of photonic crystal fiber, we observe the simultaneous generation of two visible radiation components. Frequency-resolved optical gating experiments combined with analysis and modal simulations suggest that the mechanism for their generation is third-harmonic conversion of the fundamental pulse and its split Raman self-shifted component.