All-fiber nonlinear optical wavelength conversion system from the C-band to the mid-infrared

We demonstrate an all-fiber wavelength conversion system from the C-band to the wavelength range of 2.30-2.64 µm of the mid-infrared (MIR). A series of nonlinear processes is used to perform this spectral shift in excess of 80 THz; from optical pulses in the C-band, self-phase modulation spectral broadening and offset filtering generate probe pulses in the C- and L-band. In parallel to this, Raman-induced soliton self-frequency shift converts pulses from the C-band into pump pulses in the 2 µm wavelength band. The resulting synchronized probe and pump pulses interact via degenerate four-wave mixing to produce wavelength-converted idler pulses in the MIR. Silica fiber is used for nonlinear processes at wavelengths $ {\lt} 2\;{\unicode{x00B5}{\rm m}}$<2µm whereas chalcogenide glass is used for nonlinear processes at wavelengths $ {\ge} 2\;{\unicode{x00B5}{\rm m}}$≥2µm. This system is a major step toward the development of compact MIR optical sources generated from widespread pump lasers of the C-band.