Reverse pillar chalcogenide glass waveguides with ultraflat and low dispersion profile over an ultrawide bandwidth

Two types of reverse pillar integrated chalcogenide glass (As₂S₃) waveguides are proposed in this study. These geometries exhibit an ultraflat and low dispersion profile with four zero dispersion wavelengths. Its low dispersion is approximately ±10  ps/nm/km over a 2240 nm bandwidth (for L waveguide) and ±13  ps/nm/km over a 2030 nm bandwidth (for F waveguide). Waveguide dispersion engineering is achieved by tuning the structural parameters of the waveguide, which has less sensitivity to the variations of structural parameters compared with silicon pillar waveguides. Moreover, the nonlinear coefficient and phase-matching condition in four-wave mixing (FWM) showed a great potential for broadband FWM processes in the near- and middle-infrared regions.