High-power mid-infrared frequency comb source based on a femtosecond Er:fiber oscillator

We report on a high-power mid-infrared (MIR) frequency comb source based on a femtosecond (fs) Er: fiber oscillator with a stabilized repetition rate of 250 MHz. The MIR frequency comb is produced through difference frequency generation in a periodically poled MgO-doped lithium niobate crystal. The output power is about 120 mW, with a pulse duration of about 80 fs and spectrum coverage from 2.9 to 3.6 mu m, and the single comb mode power is larger than 0.3 mu W over the range of 700 nm. The coherence properties of the produced high-power broadband MIR frequency comb are maintained, which was verified by heterodyne measurements. As the first application, the spectrum of a similar to 200 ppm methane-air mixture in a short 20 cm glass cell at ambient atmospheric pressure and temperature was measured. (C) 2013 Optical Society of America