Broadband coherent light generation in a Raman-active crystal driven by two-color femtosecond laser pulses*

We demonstrate broadband light generation by focusing two-color ultrashort laser pulses into a Raman-active crystal, lead tungstate (PbWO$_{4}$). As many as 20 Anti-Stokes and 2 Stokes fields are generated due to strong near-resonant excitation of a Raman transition. The generated spectrum extends from infrared, through the visible region, to ultraviolet, and consists of discrete spatially-separated sidebands. Our measurements confirm good mutual spatial and temporal coherence among the generated fields, and open possibilities for synthesis of subfemtosecond light waveforms.