Photonic bound states in two-dimensional photonic crystals probed by coherent-microwave transient spectroscopy

The photonic analog of a semiconductor quantum well (QW) is constructed for the first time to our knowledge from two-dimensional periodic dielectric arrays. A sharp transmission peak is observed in the photonic band-gap spectral region of the barrier and is attributed to resonant transmission of an electromagnetic wave through a photonic bound state in this structure. In contrast with bound-state energy levels in semiconductor QW’s, the photonic bound state shifts to a higher frequency as the well width is increased, and a second bound state appears on the lower-frequency side.