Summary form only given. Spontaneous emission represents a loss mechanism that fundamentally limits the performance of semiconductor lasers. The rate of spontaneous emission may, however, be controlled by a new class of periodic dielectric structures known as photonic crystals. Although a three-dimensional periodic structure may rigorously forbid spontaneous emission within a frequency interval, a simpler-to-fabricate two-dimensional (2-D) periodic structure may also introduce a large suppression of spontaneous emission