The infrared comb is generated by the difference of fundamental frequency of femtosecond mode-locked fiber laser pulse

A fiber differential frequency generation (DFG) infrared comb based on femtosecond mode-locked fiber laser pulse fundamental frequency light and its development technology are reported. Based on the self-developed repetition frequency locked 200 MHz femtosecond mode-locked erbium-doped fiber laser, the length of near zero dispersion OFS fiber (model: OFS-980-20) is optimized through chirped pulse fiber amplification and supercontinuum generation technology, and the accurate synchronous fundamental frequency bicolor pulse is obtained by combining the adjustable delay line; Using GaSe as a nonlinear crystal and optical rectification technology, a DFG infrared optical comb with a maximum spectral width of 1.3 µ m can be produced, which can be tuned broadly in the range of 6-10 µ m. This optical fiber far infrared comb is expected to play an important role in the field of precise measurement of molecular spectra.