title: Nonlinear frequency conversion in waveguide directional couplers.
abstract: Nonlinear optical effects for frequency conversion require a phase-matching condition to efficiently generate a coherent field at the new wavelength. We find that the phase-matching condition can be replaced by a resonance condition when the nonlinear effect takes place in a waveguide directional coupler. We apply this theory to second-harmonic generation and find a theoretical conversion efficiency of 100%, equivalent to the perfect phase-matching condition. An example of the design of such waveguide directional coupler is presented.
authors.affiliation: Photonic Systems Group, Department of Electrical and Computer Engineering, McGill University, 3480 University Street, Montreal, QC, H3A 2A7, Canada. podong@photonics.ece.mcgill.ca
authors.forename: Po
authors.initials: P
authors.lastname: Dong
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Kirk