Integrated photonics is a powerful platform that can improve the performance
and stability of optical systems, while providing low-cost, small-footprint and
scalable alternatives to implementations based on free-space optics. While
great progress has been made on the development of low-loss integrated
photonics platforms at telecom wavelengths, visible wavelength range has
received less attention. Yet, many applications utilize visible or near-visible
light, including those in optical imaging, optogenetics, and quantum science
and technology. Here we demonstrate an ultra-low loss integrated visible
photonics platform based on thin film lithium niobate on insulator. Our
waveguides feature ultra-low propagation loss of 6 dB/m, while our microring
resonators have an intrinsic quality factor of 11 million, both measured at 637
nm wavelength. Additionally, we demonstrate an on-chip visible intensity
modulator with an electro-optic bandwidth of 10 GHz, limited by the detector
used. The ultra-low loss devices demonstrated in this work, together with the
strong second- and third-order nonlinearities in lithium niobate, open up new
opportunities for creating novel passive, and active devices for frequency
metrology and quantum information processing in the visible spectrum range
