Abstract

The generation of second harmonic light in optically modified fibers¹ and thin films² has been shown to arise from a periodic modulation of the second-order susceptibility, χ⁽²⁾, along the direction of propagation.³ This longitudinal modulation allows the phase matching of the generated second harmonic light with the fundamental wave. The efficiency of the second harmonic for different waveguiding modes and different polarizations is governed by an additional modulation in the transverse direction. The overlap of χ⁽²⁾ with the transverse profiles of the optical electric fields across the waveguide, as described by the overlap integral, governs the modal response of the waveguide generated light.⁴ Unlike the traditional second harmonic generation (SHG) processes, the overlap integrals describing higher order modal combinations may be on the same order as the overlap integral describing the combination of the lowest order modes. In planar waveguides the difference in the transverse charge density governs the polarization dependence.

© 1995 Optical Society of America