Active wavelength tuning of dispersive wave in on-chip mid-infrared supercontinuum

Dispersive waves (DWs), which are generated at phase-matched (PM) wavelengths, are key mechanisms for spectral broadening of Supercontinuum. However, the PM wavelength is fixed once the waveguide material and geometry are determined, which results in a fixed DW wavelength. In this study, we demonstrate that DW wavelength can be actively controlled in a single device by modulating dispersion through modal coupling. An additional waveguide is placed near the main waveguide, where the optical mode is excited, to induce mode hybridization, which leads to a localized variation in dispersion. Adjusting the gap between waveguides within a 450 nm range changed the red-side zero-dispersion wavelength from 1.8 µm to 2.8 µm and controlled DW wavelength from 3.2 µm to 4.7 µm when using 1550 nm pump, covering fundamental vibrational modes of various molecules. These results demonstrate the potential for application in spectroscopy, such as selective molecular detection in a single device.