True-time tunable and spectrally-isolated dispersive wave generation by manipulating thermo-optic birefringence of lithium niobate on insulator waveguide
Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, National Engineering Research Center for Optical Instruments, Zhejiang University, 310058, Hangzhou, China
2 Ningbo Research Institute, Zhejiang University, 315100, Ningbo, China
Accepted: 15 December 2022
Published online: 11 January 2023
Dispersive wave emission from a high-order dispersion perturbed soliton during the supercontinuum generation can efficiently and directionally transfer the soliton pump energy to the desired wavelength regime, which has a localized spectral structure and maintains the coherence of pump. However, it remains challenging to tune the central wavelength of dispersive wave in a true-time manner because conventional tuning methods depend on the lithography control of the waveguide geometry. In this work, we numerically show that manipulating the thermo-optic birefringence of a thin-film lithium niobate on insulator (LNOI) waveguide, the spectrally-isolated dispersive wave induced by a mode hybridization effect can be thermally tuned. The method is realized in a single suspended LNOI ridge waveguide with thermo-electrodes loaded, regardless of massed waveguide arrays with different geometries and many times of edge-coupling. We show that the mode hybridization dispersive wave (MH-DW) presents a distinguishable isolated spectrum and a broad tuning range up to 200 nm within the temperature of 25 to 500 °C, which is 15 folds larger than that of the conventional dispersive wave (C-DW). Furthermore, the spectrum intensity of the MH-DW can be ~ 20 dB larger than that of the C-DW. We believe this work opens an avenue to true-time tunable spectrum isolation and enhancement in chip-scale supercontinuum generation and its potential applications in spectroscopy at highly targeted frequencies, narrow-band frequency-swept sources, and spectrally-isolated frequency combs generation, etc.
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