Abstract: Quasi-phase matched (QPM) second-harmonic (SH) generation in the reflection geometry is described. The SH intensity can be strongly enhanced by spatially modulating the optical properties of the nonlinear medium. This type of quasi-phase matching is demonstrated using an Al.sub.0.8 Ga.sub.0.2 As/GaAs heterostructure designed for .lambda.=1.06 .mu.m incident light. The SH light intensity generated in reflection from the heterostructure is enhanced 70 times relative to the SH response of a homogeneous GaAs wafer. A Fabry-Perot resonant cavity design employs this structure to make thin films with extremely high SH generation efficiencies. This is of particular interest used in vertical cavity surface emitting lasers (VCSELs).

Abstract: A plurality of signals are mixed in a non-linear waveguide for generating a near field sum frequency output pattern. The near field output pattern is monitored for changes which correspond to changes in the phase relationship between the plurality of signals. A grating provides a mask through which the near field pattern may propagate. Detectors positioned above the grating at predetermined locations measure the intensity of the near field pattern and a change in the phase relationship between the input signals is determined from a change in the intensity of the near field output pattern.

Abstract: An optical signal deflector comprising an optical signal waveguide formed of plural layers of optically non-linear semiconductor material, apparatus for launching a first optical signal in the waveguide in a first direction which is parallel to the layers, apparatus for applying a second optical signal to the waveguide in a second direction parallel to the layers but at an angle to the first direction, the thickness and indexes of refraction of the layers being predetermined to cause non-linear field contributions of the signals to add in phase in the far field, whereby a third optical signal is obtained having an angle of emission which is the three dimensional vector addition, at a harmonic sum frequency, of the first and second signals.

Abstract: Optical multilayer structures for harmonic laser emission are disclosed. The multilayer structures are made of plurality of layers of different optically nonlinear semiconductor materials. The thicknesses, locations and refractive indices of the layers are designed, according to a modified Fourier transform, to give a broad bandwidth for interaction of fundamental light fields. Various applications are envisioned and described, e.g. spectrometers, non-blocking switching systems, wavelength division multiplexing fiber optic receivers etc.

Abstract: Sum frequency generating devices are disclosed. The devices include a waveguide having a multilayer structure comprising at least one nonlinear semiconductor material. In a preferred embodiment, each of the layers of the multilayer structure has the same thickness and alternate layers have a first and a second predetermined refractive index. The sum frequency output generated by two contra-propagating beams of fundamental wavelengths within the waveguide is enhanced by the multilayer structure of the waveguide. The sum frequency output is in a direction different from that of the waveguide and contrapropagating fundamental beams.