  The conditions of critical coupling of light to Tamm plasmons are
investigated with comprehensive numerical simulations, highlighting the
parameters that maximise absorption of incident light in the metal layer. The
asymmetric response in reflection and absorption with respect to the direction
of incidence is discussed, the two cases yielding different optimal coupling
conditions. These findings are relevant for the design of optimised Tamm
structures, particularly in applications such as narrow-band thermal emitters,
field-enhanced spectroscopy and refractive-index sensing.
