Polarization Anisotropy of Optical Gain in Two-Dimensional Photonic Crystals with Active Lattice Points

Polarization anisotropic properties of optical gain are theoretically investigated for the first time for photonic crystals with active lattice points, in which all lattice points are made of the same gain material embedded in other dissipative medium. The study of light scattering by an isolated gain cylinder rod indicates that the reaction producing optical gain for the light whose electric field is parallel to the rod axis always occurs more strongly than that for the one perpendicular to it. This anisotropy stems from the geometrical asymmetry of the rod. This polarization anisotropy is taken over by the above photonic crystal, i.e., the periodic array of gain rods. In photonic crystals, however, the anisotropy becomes more sensitive to the variation of the rod radius than in an isolated rod. Morever, the polarization anisotropy is found to be more pronounced for smaller rod radii or longer periods, indicating that it is approximately determined soley by the filling rate of the rod. These results can be regarded as a consequence of periodic arraying of multiple gain rods.