Ultrabroadband supercontinuum generation with low energy consumption on dispersion-engineered lithium-niobate-on-insulator waveguides

Lithium niobate on insulator (LNOI) offers the opportunity for chip-scale self-referenced frequency standards by enabling simultaneous ultrabroadband supercontinuum and second-harmonic generation. This is achieved through precise dispersion engineering and strong, diverse nonlinearities of submicron waveguides with low pump power. Out of consideration for low-power, chip-scale applications where the pump power is limited, optimizing the waveguide dispersion and extending the waveguide length are essential to achieve enhanced spectral flatness and improved energy efficiency. In this work, we report ultrabroadband supercontinuum generation on a dispersion-engineered waveguide on LNOI, achieving a 30 dB spectral bandwidth of over 1650 nm under a pulse energy below 80 pJ. Based on the above generated supercontinuum spectrum, we measured spectra1 response of two integrated edge coupler designs---monolayer and bilayer taper structure from 600 to 2400 nm. This chip-scale supercontinuum source offers low energy consumption, integration, and high coherence, making it a compelling complement to commercial sources and enabling applications, including spectroscopy, optical coherence tomography, midinfrared sensing, and quantum photonics.