Enhanced Kerr nonlinearity in sub-wavelength diameter As_2Se_3 chalcogenide fiber tapers

Abstract

We experimentally demonstrate enhanced Kerr nonlinear effects in highly nonlinear As₂Se₃ chalcogenide fiber tapered down to subwavelength waist diameter of 1.2 µm. Based on self phase modulation measurements, we infer an enhanced nonlinearity of 68 W^-1m^-1. This is 62,000 times larger than in standard silica singlemode fiber, owing to the 500 times larger n ₂ and almost 125 times smaller effective mode area. We also consider the potential to exploit the modified dispersion in these tapers for ultra-low threshold supercontinuum generation.