  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.
