Lasing mechanism in two-dimensional photonic crystal lasers

We conduct a comprehensive investigation of the lasing mechanism in a photo nic crystal slab laser with a refractive index that is periodic in two dime nsions. Experimental spectra of laser structures fabricated with organic ga in media are presented. It is found that lasing frequencies can be explaine d in terms of Van Hove singularities in the density of modes. We also obser ve lasing spectra that cannot be obtained from structures with one-dimensio nal periodicity, such as traditional distributed feedback lasers. Lasing fr equencies an computed using numerical techniques.