Apparatus and methods for generating mid-IR frequency combs using intra-pulse DFG. A mode-locked pulse generation laser generates near-IR pulses which are amplified. The amplified pulses are spectrally broadened by a nonlinear element, for example a normal dispersion highly nonlinear fiber (ND-HNLF) to generate broadened pulses. The nonlinear spectral broadening element is a transparent dielectric material having a cubic nonlinear response. Broadened pulses are temporally compressed to generate short, high-power pulses which few-cycle conditioned pulses which are ready for the intrapulse DFG process. The DFG block generates a mid-IR comb by difference frequency generation. It might comprise an orientation patterned GaP (OP-GaP) crystal or a poled lithium niobate (PPLN) crystal.
We present a new approach to generating a coherent comb of infrared frequencies utilizing intra pulse difference frequency generation. The central claims of this invention are:
Our invention provides a robust source of coherent light in the infrared, that is difficult to obtain otherwise. There is rapid growth and increasing interest in this region of the spectrum because it is extremely important for spectroscopy, materials science, microscopy, chemistry, trace gas sensing, health diagnostics, to name a few.