Modification of Absorption of a Bulk Material by PhotonicCrystals

We show theoretically that it is possible to modify absorption of a bulk absorbing material by inserting another non-absorbing dielectric slab periodically to form one-dimensional photonic crystals. It is found that, for frequencies within photonic bandgaps, absorptance is always suppressed. For frequencies located at photonic bands, absorptance can be suppressed or enhanced, which depends on the relative values of the real refactive index of the absorbing and non-absorbing dielectric layers.