Spontaneous emission and nonlinear effects in photonic bandgap materials

We present results of theoretical and experimental investigations into spontaneous emission alteration and nonlinear optical effects in thin-film multilayer devices. We begin with a brief section on one-dimensional photonic band gaps (PBGs) and photonic band edges. We then introduce the concept of nonlinear optical effects in PBG structures with the outline of the method of operation of an all-optical PBG switch. Next, we model a device that exhibits passive anisotropic optical transmission—the analogue of the electronic diode. This structure is designed to exhibit a greater shift in the location of the photonic band edge for light incident from one direction than from the opposite direction. Finally, we show enhancement of the spontaneous emission power spectrum of an emitter that is localized within a PBG structure—without the use of a typical microcavity—for frequencies near the photonic band edge. Two slightly different AlAs/AlGaAs/GaAs semiconductor PBG light emitting diodes (LEDs) were designed and fabricated. The emission spectra of these structures were measured and compared with that of a reference GaAs LED. We use a novel method for modeling the emission rate from within the structures.