Enhancement of optical gain in two-dimensional photonic crystals with active lattice points

Photonic crystals with active lattice points (two-dimensional gain photonic crystals) are proposed, in which all lattice points are made of the same gain material embedded in other dissipative medium. The optical gain spectrum is found to exhibit a pronounced gain enhancement in the vicinity of the band edge of the photonic band. This gain value also shows a spatial anisotropy reflecting the symmetry of the photonic band. These gain values have a strong correlation with the variation of the group velocity of light, indicating that;he marked reduction in the group velocity near the photonic band edge causes the optical gain enhancement.