Abstract: An electro-optic waveguide polarization modulator (20) comprising a waveguide core (4) having first and second faces defining a waveguide core plane, a plurality of primary electrodes (22, 24) arranged at a first side of the waveguide core plane and out of said plane, and at least one secondary electrode (26) arranged at a second side of the waveguide core plane and out of said plane, wherein the electrodes (22, 24, 26) are adapted in use to provide an electric field having field components (13, 15) in two substantially perpendicular directions within the waveguide core (4) so as modulate the refractive index thereof such that electromagnetic radiation propagating through the core (4) is converted from a first polarization state to a second polarization state.

Abstract: A horizontal access semiconductor photo detector (2) comprises a horizontal light absorbing layer (8) for converting light into photo-current which layer is configured to confine light within it in whispering gallery modes of propagation. The detector is configured to have a first waveguide portion (18) and a second light confining portion (20, 21) arranged such that the waveguide portion couples light into the detector and transfers light into the light confining portion so as to excite whispering gallery modes of propagation around the light confining portion. The light absorbing layer may be part of the light confining portion or alternatively light can be coupled into the light confining portion or alternatively light can be coupled into the light absorbing layer from the light confining portion by evanescent coupling. The excitation of whispering gallery modes within the light absorbing layer significantly increases the effective absorption coefficient of the light absorbing layer.

Abstract: A horizontal access semiconductor photo detector (2) comprises a horizontal light absorbing layer (8) for converting light into photo-current which layer is configured to confine light within it in whispering gallery modes of propagation. The detector is configured to have a first waveguide portion (18) and a second light confining portion (20, 21) arranged such that the waveguide portion couples light into the detector and transfers light into the light confining portion so as to excite whispering gallery modes of propagation around the light confining portion. The light absorbing layer may be part of the light confining portion or alternatively light can be coupled into the light confining portion or alternatively light can be coupled into the light absorbing layer from the light confining portion by evanescent coupling. The excitation of whispering gallery modes within the light absorbing layer significantly increases the effective absorption coefficient of the light absorbing layer.

Abstract: A device for spatially separating components of frequency in a primary radiation beam comprising means for separating the primary radiation beam into a plurality of secondary radiation beams, a plurality of electrically biasable waveguides forming a waveguide array, each for transmitting a secondary radiation beam to an output, wherein each waveguide has an associated optical delay line having a corresponding optical delay time, wherein each of the optical delay times is different. The device also comprises means for applying a variable electric field across each of the waveguides such that the phase of the secondary radiation beams transmitted through each may be varied by varying the electric field. The secondary radiation beams output from each of the waveguides interfere in a propagation region with a secondary radiation beam output from at least one of the other waveguides so as to form an interference pattern comprising one or more maximum at various positions in the propagation region.

Abstract: An electro-optic waveguide device (10) comprises an assembly of waveguides (30) connected to a common light input region (41) and forming a common far field diffraction pattern (44). The device (10) comprises an n.sup.+ GaAs substrate (14) bearing a waveguide lower cladding layer (16) of n.sup.+ Ga.sub.0.9 Al.sub.0.1 As, which is in turn surmounted by a waveguide core layer (18) of n.sup.- GaAs. The layer (18) has grooves (20) defining the waveguides (30), each of which has a respective Schottky contact (32). Each contact (32) is biased negative with respect to the substrate (14), which reverse biases the respective Schottky diode waveguide structure. The waveguide core layer (18) has electro-optic properties, and its refractive index varies with electric field. The phase of light emerging from each waveguide is therefore independently variable by means of its applied bias voltage.