Cascaded photonic crystal guides and cavities:: Spectral studies and their impact on integrated optics design

We report on the investigation of cavities coupled to channel waveguides defined in a triangular-lattice photonic crystal etched into a GaAs/AlGaAs heterostructure waveguide. We make use of the internal probe technique by selectively exciting the photoluminescence of InAs dots embedded in the planar waveguide. We collect at the nearby cleaved edge the fundamental mode transmitted through the channel waveguides. From the study of a number of basic cases, we exemplify how one may deduce the main guideline design rules for given cavity-guide interaction mechanisms and then for the implementations of functions such as bending and filtering. In particular, the role of the so-called ministopband (MSB) feature of the waveguide and the nature of the cavity modes involved are outlined.