Abstract: An optical signal switch has improved port isolation and extinction ratio by utilizing cascaded or tandem Mach-Zehnder Interferometer (MZI) with thermo-optical or electro-optical refractive index-modulating electrodes on the MZI arms.

Abstract: A high-performance electro-optic intensity modulator using two polymeric waveguides having a high extinction-ratio modulation process is implemented by the coupling-out effect of induced grating modulation. The two waveguides can be either single-mode or multi-mode, even highly multimode. The inducing of a modulated grating-coupler in a waveguide channel makes the coupling between two waveguides become unidirectional and the coupling efficiency can be achieved to a very high value in theory. The two waveguide channels in this intensity modulator may have large dimensions, so the device can support either single-mod or multi-mode operation. The electro-optic waveguide intensity modulator may be used either as a single optical modulator/switch or as a waveguide modulator/switch array for fiber-optic communication.

Abstract: An optical waveguide switch using two unidirectional waveguide couplers with coupling gratings is provided. Each unidirectional waveguide coupler compromises two waveguide channels and a coupling grating along one waveguide channel. Two such waveguide couplers with coupling gratings are positioned on a substrate to form a symmetric couple-pair. An optical signal launched into the input port of the first coupler may exit from the output port of the second coupler. A modulating electrode is used to eliminate the coupling gratings on the two couplers, and the optical signal launched into the input port of the first coupler exits from its own output port. Similarily, this process can also be performed for an optical signal launched into the second coupler. Thus an effective 2×2 switching performance is implemented with this structure. M×N switching performance may also be implemented with several 2×2 waveguide switches.