Abstract: An embodiment of the invention provides a coupled waveguide photo detector device. Optically, the device includes an input waveguide. An output waveguide is coupled to the input waveguide with a nonuniform coupling coefficient in a coupling section. An absorber is included in the coupling section to convert an absorbed portion of optical radiation into photo current. The location of absorber and the optical radiation intensity pattern in the coupling section are set to control the maximum intensity of output power absorbed by the output waveguide to be within a predetermined limit that avoids saturation. The absorber is also part of a transmission line collector which has a phase and group velocity to match those of the optical wave in the coupling section such that currents collected by the transmission line collector add in phase as the optical wave propagates in the output waveguide.

Abstract: A method for optical modulation comprising the steps of guiding an optical wave in an optical waveguide, the optical wave having an evanescent tail; and applying a modulation voltage to the evanescent tail.

Abstract: In the band edge region, transmission and reflection of an optical wave can be made very sensitive to the change in radiation wavelength, a change in the modulator material refractive index, and/or a change in the material absorption. Controlling these parameters with the increased level of sensitivity is provided by modulation using the band edge region. A preferred embodiment method of the invention uses a periodic optical structure (i.e., a grating) on top of an optical waveguide structure. The combination of the periodic structure and the optical waveguide is designed so that the reflection and/or transmission of the guided wave have broad pass bands with narrow transition bands. The optical structure is exposed to an incident laser radiation with wavelength in one of the transition bands. Modulation of the incident laser radiation is controlled by the change in refractive index or absorption in the optical guided wave structure produced by the modulation voltage.

Abstract: In the band edge region, transmission and reflection of an optical wave can be made very sensitive to the change in radiation wavelength, a change in the modulator material refractive index, and/or a change in the material absorption. Controlling these parameters with the increased level of sensitivity is provided by modulation using the band edge region. A preferred embodiment method of the invention uses a periodic optical structure (i.e., a grating) on top of an optical waveguide structure. The combination of the periodic structure and the optical waveguide is designed so that the reflection and/or transmission of the guided wave have broad pass bands with narrow transition bands. The optical structure is exposed to an incident laser radiation with wavelength in one of the transition bands. Modulation of the incident laser radiation is controlled by the change in refractive index or absorption in the optical guided wave structure produced by the modulation voltage.