Abstract

It has been shown recently [1], that a sum-frequency signal generated in one-dimensional photonic bandgap (PBG) structure with a high contrast of the refractive index modulation, may be increased more than by one order of magnitude. This happens because of an increase of the electromagnetic field density at the fundamental frequencies near the photonic band gap edge, or nonphase-matching enhancement, and grating assisted phase matching, i.e. quasi-phase-matching (QPM) [2] enhancement. However, in the real experiment [1], at the collinear geometry of wave interaction, the QMP conditions near the photonic band gap edge are fulfilled approximately. Here we study, using the propagating matrix method, the enhancement of sum-frequency generation in one-dimensional PBG structure under condition of noncollinear geometry of wave interaction. The optimal angle between two incident fundamental waves is calculated to realize exact QPM and non-phase-matching enhancement conditions near the photonic band edge simultaneously. In this case, the intensity of generated reflected or transmitted sum-frequency signal may be increased in a few times compared with a case of collinear wave interaction. We show also that at specific angles of incidence the values of effective refractive indexes of two fundamental and sum-frequency waves are equal near photonic band adge. This gives rise to enhancement of noncollinear signal due to dispersive phase matching and non-phase-matching enhancement.

© 2001 EPS