Mid-infrared difference-frequency generation of ultrashort pulses tunable between 3.2 and 4.8 μm from a compact fiber source

We report single-pass difference-frequency generation of mid-infrared feratosecond pulses tunable in the 3.2-4.8 mu m range from a two-branch mode-locked erbiura-doped fiber source. Average power levels of up to 1.1 mW at a repetition rate of 82 MHz are obtained in the mid infrared. This is achieved via nonlinear mixing of 170 mW, 65 fs pump pulses at a fixed wavelength of 1.58 mu m, with 11.5 raW, 40 fs pulses tunable in the near-infrared range between 1.05 and 1.18 mu m. These values indicate that the tunable near-infrared input component is downconverted with a quantum efficiency that. exceeds 30%. (c) 2007 Optical Society of America.