  It is shown that two fundamentally different phenomena, the bound states in
continuum and the spectral singularity (or time-reversed spectral singularity),
can occur simultaneously. This can be achieved, in particular, in a rectangular
core dielectric waveguide with embedded active (or absorbing) layer. In such a
system a two-dimensional bound state in a continuum is created in the plane of
a waveguide cross section and it is emitted or absorbed along the waveguide
core. The idea can be used for experimental implementation of a laser or a
coherent-perfect-absorber for photonic bound state that resides in a continuous
spectrum.
