The flux-flow critical current as a function of transverse magnetic field for an oxygen-doped Al film perforated with a two-dimensional triangular lattice pattern of holes shows pronounced structure at harmonically related values of the applied magnetic field. Effects at thecharacteristic fields are interpreted in terms of the interaction between commensurate flux-line sublattices, one of which is strongly pinned to the holes by the vortex-hole coupling force and the other of which is located interstitially between the hole-lattice sites. A model is proposed for the vortex-hole coupling force which, in conjunction with a treatment of vortex-vortex interactions, qualitatively accounts for the observed temperature and field dependence of these harmonically related critical currents.

We report the first demonstration of channel optical waveguide directional couplers. The closely spaced channel waveguides were fabricated in GaAs by proton implantation. Optical coupling was observed at 1.15 μ with complete light transfer out of the initial channel into adjacent channels in lengths of typically 2 mm.

No abstract

A proposal for a new method of phase matching in nonlinear optical interactions is made. A periodic perturbation of the surface of a thin-film waveguide generates space harmonics with new propagation constants which can be phase matched. An analysis of this proposal shows it to be particularly interesting for a class of thin-film nonlinear devices using the cubic optically isotropic semiconductors (such as GaAs, GaP, etc.) which possess high nonlinear optical coefficients but are not phase matchable by the conventional birefringent techniques.

No abstract