“Acceptor impurity” mode in 1-D holographic photonic crystals achieved by controlling polarization state of the incident beam

Abstract

The critical incident angle – “general Brewster’s angle” is introduced. The effective “acceptor impurity” in 1-D photonic crystals can be achieved by controlling the polarization state of the incident beam at this critical angle. When a beam with S-polarization is incident on a photonic crystal at this angle, the forbidden band still remains as it is. However, when a beam with P-polarization is incident on the same photonic crystal at this angle the forbidden band will vanish. This means that in the background of the forbidden band of S-polarization, the incident beam with P-polarization can still pass through the photonic crystal. Thus, a status equivalent to the “defect mode” in semiconductors can be induced by controlling the polarization state of the incident beam. This kind of “polarization defect” can be controlled in real-time during practical use rather than being predetermined during fabrication of the photonic crystal, as is the case with traditional defects. A photonic crystal can, therefore, be used either as one without “defects” or as one with “defects”. The theoretical analysis and experimental verifications are given in details.