Abstract

Quasi-phase matching (QPM)¹ is a well-established technique for achieving efficient frequency conversion. QPM structures have a uniform refractive index, and a periodic quadratic nonlinearity. The nonlinearity is usually periodic in one direction, and is piecewise constant in strips. A two-dimensional generalization was recently proposed by Berger² and studied experimentally by Broderick et al^.3 In Broderick’s samples, the re-fractive index is again uniform, but the periodicity derives from an hexagonal lattice, with a single hexagon in each unit cell in which the nonlinearity is inverted.

© 2001 Optical Society of America