Flat and broadband supercontinuum generation by four-wave mixing in a highly nonlinear tapered microstructured fiber.

We have demonstrated broad supercontinuum (SC) generation by using a highly nonlinear tapered tellurite microstructured fiber pumped by a 15-ps-pulsed laser with the peak power of 375 W. The fiber is characterized with a short section with a large diameter followed by a long section with a small diameter. The SC was mainly generated in the last 30-cm-long section which had a core diameter of 0.9 μm and a zero dispersion wavelength around the pump wavelength. Such a core size and a dispersion profile were chosen to ensure the SC was mainly broadened by phase matched four-wave mixing. The SC spans from UV to mid IR. The 10 dB spectrum is from 780 to 1890 nm. The input peak power is much lower than conventionally adopted in the picosecond regime. The constructed SC light source is cost-effective, since neither femtosecond pulsed laser nor high power picosecond pulsed laser is adopted.