Enhanced /spl chi//sup (2)/ interactions near the band-edge of finite, one-dimensioaal photonic band gap structures

One of the most intriguing aspects related to the /spl chi//sup (2)/ response of PBG crystals that still remains unresolved is the possibility of greatly enhancing the conversion efficiency of nonlinear processes. The enhancement of SHG is perhaps the best example. The processes that we discuss owe their increased efficiency to the simultaneous availability of: (1) exact phase matching conditions (1); and (2) high localization of the fields with frequencies tuned at transmission resonances near the photonic band edge. The nonlinear dynamics of the field envelopes in the SHG case may be described by a first order perturbative approach. As an example we calculate the second harmonic conversion efficiency of a new type of blue laser that could operate in the 400 nm range, based on a one-dimensional PBG structure.