  Dark matter (DM) with masses of order an electronvolt or below can have a
non-zero coupling to electromagnetism. In these models, the ambient DM behaves
as a new classical source in Maxwell's equations, which can excite potentially
detectable electromagnetic (EM) fields in the laboratory. We describe a new
proposal for using integrated photonics to search for such DM candidates with
masses in the 0.1 eV - few eV range. This approach offers a wide range of
wavelength-scale devices like resonators and waveguides that can enable a novel
and exciting experimental program. In particular, we show how refractive
index-modulated resonators, such as grooved or periodically-poled microrings,
or patterned slabs, support EM modes with efficient coupling to DM. When
excited by the DM, these modes can be read out by coupling the resonators to a
waveguide that terminates on a micron-scale-sized single photon detector, such
as a single pixel of an ultra-quiet charge-coupled device or a superconducting
nanowire. We then estimate the sensitivity of this experimental concept in the
context of axion-like particle and dark photon models of DM, showing that the
scaling and confinement advantages of nanophotonics may enable exploration of
new DM parameter space.
