Design and modelling of all-normal dispersion As₃₉Se₆₁ chalcogenide photonic crystal fiber for flat-top coherent mid-infrared supercontinuum generation

A. Medjouri and DjamelAbed 

Volume 50, July 2019, Pages 154-164

Optical Fiber Technology

https://doi.org/10.1016/j.yofte.2019.03.021

Abstract

We report numerical investigation of mid-infrared supercontinuum (SC) generation in all-normal dispersion (ANDi) As₃₉Se₆₁ chalcogenide photonic crystal fiber (PCF). Numerical results, obtained by using the Finite-Difference Frequency-Domain (FDFD) method, indicate that desirable dispersion properties can be achieved by adjusting the air holes diameter and ANDi regime is obtained over the entire wavelength range with a PCF pitch and air holes diameter of 1.8 µm and 0.7 µm, respectively. Besides, the optimized design has a nearly zero dispersion wavelength of 3.45 µm and exhibits high Kerr nonlinearity of 5.89 w⁻¹ m⁻¹. By pumping 50 fs duration laser pulses at 3.45 µm, we demonstrate the generation of a broad, ultraflat-top and highly coherent SC spectrum extending from 2.43 µm to 4.85 µm at 4 dB spectral flatness and from 1.95 µm to 6.58 µm at 8 dB, by employing very low energy pulses of 50 pJ and 250 pJ, respectively. Owing to its remarkable optical characteristics, the proposed SC source based on As₃₉Se₆₁ chalcogenide glass PCF is found to be suitable for various potential mid-infrared applications such as optical coherence tomography, mid-infrared spectroscopy and metrology.

Keywords

Nonlinear fiber optics, Supercontinuum generation, As₃₉Se₆₁ chalcogenide glass, Photonic crystal fiber.