Self-focusing of narrow one-dimensional beams in photonic microcavity arrays

The self-focusing of one-dimensional spatial beams is studied in resonant periodic structures that consist of a linear array of coupled planar photonic microcavities. Self-focusing results from the nonlinear phase shift that is due to refractive detuning of the intraband resonance. Coupled with this resonance enhancement of the nonlinearity is the strong modification of linear diffraction, which can take on negative, positive, or zero values. Even in the regime where diffraction is significantly enhanced compared with that of bulk media, the self-focusing intensity threshold is reduced. The power throughput of the self-focused beam through the microcavity structure is also greater than for operation at the band edge of a photonic bandgap structure because of the broader nature of the intraband resonance. (C) 2003 Optical Society of America.