  UV and visible photonics enable applications ranging from spectroscopic
sensing to communication and quantum information processing. Photonics
structures in these wavelength regimes, however, tend to experience higher loss
than their IR counterpart. Particularly in the near-UV band, on-chip optical
microresonators have not yet achieved a quality factor beyond 1 million. Here
we report ultra-low-loss photonic waveguides and resonators patterned from
alumina thin films prepared by a highly scalable atomic layer deposition
process. We demonstrate ultra high Q factor of 1.5$\,\times\,$10$^6$ at 390nm,
a record value at UV bands, and 1.9$\,\times\,$10$^6$ at 488.5nm.
