Increased Red Frequency Shift in Coherent Mid-Infrared Supercontinuum Generation from Tellurite Microstructured Fibers

We investigate coherent broadband mid-infrared supercontinuum generation in all normal dispersion (ANDi) tellurite microstructured fibers through numerical simulations. The proposed tellurite microstructured fibers (PTMFs) have an inverted L-shaped ANDi profile in the wavelength range of < 5.2 μm. By using a 2-μm femtosecond laser as the pump source, the spectral broadening occurs in the PTMF, which is caused by self-phase modulation (SPM) and optical wave breaking. Interestingly, SPM induced spectral broadening is larger on the Stokes side than the antistokes side, since the trailing edge of laser pulse becomes smoother than its leading edge, and the effect of self-steepening (SS) on pulse shape is compensated by the effect of the dispersion in the PTMF. Such a phenomenon is inaccessible in previously reported optical fibers, since the trailing edge of output pulse is steeper than the leading edge of output pulse when SS occurs in previously reported ANDi fibers. As a result, coherent broadband mid-infrared supercontinuum light with long operating wavelength can be generated in the PTMF.