Abstract: A method of selectively adjusting the refractive index of the propagating portion of an optic waveguide, the method including the step of implanting into selected portions of the propagating portion of the optic waveguide a dopant material selected so as to minimise the number of additional attenuating, extrinsic charge carriers in the propagating portion of the optic waveguide.

Abstract: An optical filter has at least one input waveguide, a wavelength dispersive device receiving light from the optical input, and an optical output having a plurality of spatially separated waveguides receiving respective wavelength bands of light from the wavelength dispersive device, at least one of the waveguides in the optical output or optical input forming part of an evanescent waveguide coupler comprising a group of coupled waveguides side by side.

Abstract: An integrated optical transceiver comprising: a laser cavity formed between first and second feedback elements (3,7), wavelength selective means, eg a diffraction grating (4), within the laser cavity for determining a lasing wavelength thereof and a light receiver (10), one of the feedback elements (3) being partially transmissive at the lasing wavelength to enable the transceiver to emit radiation at the lasing wavelength, and the wavelength selective means (4) being arranged to receive light through the feedback element (3) and transmit light of a selected wavelength, differing from the lasing wavelength, to the light receiving means (10).

Abstract: A tapered rib waveguide tapering from a large, multi-mode optical waveguide to a smaller, single-mode optical waveguide, the tapered rib waveguide comprising two portions (4,5) formed of the same material: a lower portion (4) which tapers laterally from the large waveguide to the smaller waveguide and an upper portion (5) formed on the lower portion (4), which tapers to a point (or other form of termination), the dimensions of the two portions (4,5) being such that substantially all of a fundamental mode propagated in the large multi-mode waveguide is coupled to the smaller, single-mode waveguide.

Abstract: An optical fiber is connected to an optical device having a substrate with locating means, such as a V-groove, for locating the fiber on the substrate. Attachment means secure the optical fiber at a position remote from the locating means so that the fiber is held in a state of elastic deformation to assist in holding the fiber in contact with the locating means without it being secured thereto.

Abstract: A process for making a silicon rib wavegide structure is described comporising the following steps:(i) forming a window in a protective layer on the surface of a silicon wafer to expose a part of said surface;(ii) depositing a buffer layer at least over said exposed surface;(iii) carrying out an etch step to etch the buffer layer and silicon outside a protected rib portion thereby to form a silicon rib with the buffer layer on its upper surface; and(iv) forming a layer of cladding at least on side walls of the silicon rib.

Abstract: A turntable optical transmission circuit has a light source forming an input to a waveguide, a detector detecting light output from the waveguide, a comparator for comparing the output with a predetermined value to generate a difference signal and a waveguide trimmer for changing the waveguide transmission in dependence on the difference signal until the output matches the predetermined value.

Abstract: The device comprises a layer of silicon separated from a substrate by a layer of insulating material. A rib having an upper surface and two side surfaces is formed in the layer of silicon to provide a waveguide for the transmission of optical signals. A lateral doped junction is formed between the side surfaces of the rib such that an electrical signal can be applied across the junction to control the density of charge carriers across a substantial part of the cross-sectional area of the rib thereby actively altering the effective refractive index of the waveguide.

Abstract: A silicon-on-insulator chip has a location recess formed therein for receiving a laser diode. The location recess includes two non-parallel location surfaces adapted to abut against two reference surfaces formed on the laser diode. The abutment of the location surfaces against the reference surfaces enables a laser emission area of the laser diode to be accurately aligned with a rib waveguide formed on the silicon-on-insulator substrate.

Abstract: The device comprises a layer of silicon separated from a substrate by a layer of insulating material. A rib having an upper surface and two side surfaces is formed in the layer of silicon to provide a waveguide for the transmission of optical signals. A lateral doped junction is formed between the side surfaces of the rib such that an electrical signal can be applied across the junction to control the density of charge carriers across a substantial part of the cross-sectional area of the rib thereby actively altering the effective refractive index of the waveguide.