  Here we propose a route to the high-Q perfect absorption of light by
introducing the concept of a Fano anti-laser. Based on the drastic spectral
variation of the optical phase in a Fano-resonant system, a spectral
singularity for scatter-free perfect absorption can be achieved with an order
of magnitude smaller material loss. By applying temporal coupled mode theory to
a Fano-resonant waveguide platform, we reveal that the required material loss
and following absorption Q-factor are ultimately determined by the degree of
Fano spectral asymmetry. The feasibility of the Fano anti-laser is confirmed
using a photonic crystal platform, to demonstrate spatio-spectrally selective
heating. Our results utilizing the phase-dependent control of device bandwidths
derive a counterintuitive realization of high-Q perfect conversion of light
into internal energy, and thus pave the way for a new regime of
absorption-based devices, including switches, sensors, thermal imaging, and
opto-thermal emitters.
