Fiber-optic soliton self-compression to subcycle pulse widths in the mid-infrared

We demonstrate physical scenarios whereby ultrashort mid-infrared pulses even with very low pulse energies can be compressed to subcycle pulse widths using nonlinear-optical field transformations in chalcogenide photonic-crystal fibers. We show that an 85 fs pulse with a spectrum centered at 3.5 µ m can be compressed to a subcycle pulse width through a solitonic transformation inside a chalcogenide photonic-crystal fiber with a hexagonal cladding. Waveform distortions of such pulses can be suppressed, as our simulations show, by combining chalcogenide photonic-crystal fibers with carefully optimized solid-state components for accurate nonlinear phase compensation. (letter)