On-chip directional octave-spanning supercontinuum generation from high order mode in near ultraviolet to infrared spectrum using AlN waveguides

On-chip ultraviolet to infrared (UV-IR) spectrum frequency metrology is of crucial importance as a characterization tool for fundamental studies on quantum physics, chemistry, and biology. Due to the strong material dispersion, traditional techniques fail to demonstrate the device that can be applied to generate coherent broadband spectrum that covers the full UV-IR wavelengths. In this work, we explore several novel techniques for supercontinuum generation covering near-UV to near-IR spectrum using AlN micro-photonic waveguides, which is essential for frequency metrology applications: First, to create anomalous dispersion, high order mode (TE10) was adopted, together with its carefully designed high efficiency excitation strategies. Second, the spectrum was broadened by soliton fission through third order dispersion and second harmonic generation, by which directional energy transfer from near-IR to near-UV can be obtained. Finally, high quality single crystalline AlN material was used to provide broadband transparency from UV to IR. Under decently low pulse energy of 0.36 nJ, the experimental spectrum from supercontinuum generation covers from 490 nm to over 1100 nm, with a second harmonic generation band covering from 405 nm to 425 nm. This work paves the way towards UV-IR full spectrum on-chip frequency metrology applications.