Optical-gain enhancement in two-dimensional active photonic crystals

Optical-gain-enhancement effects are numerically investigated in detail for two-dimensional photonic crystals with active (gain) lattice points. First, this gain enhancement is shown to occur in the vicinity of every photonic band edge. A thorough examination is carried out to isolate the leading factors that determine this enhancement on the basis of a number of (more than 1000) numerically calculated data points. The gain-enhancement factor is uniquely determined by the product of the time for light to pass a gain rod and the confinement factor of the field energy in the gain rod, irrespective of the choice of dielectric constants, wave numbers, band indices, and polarization directions of light. In designing photonic crystals, therefore, more gentlly sloped bands and a greater contrast in the dielectric constant between gain and background materials are essential in order to intensify optical gain more effectively. (C) 2001 American Institute of Physics.