British Telecommunications Public Limited Company

The Centre for Integrated Photonics Limited

Other

British Telecommunications Corporation

Ucl Business Plc

University of Essex

British Telecommunications Public

The Centre for Intergrated Photonics Limited

Michael J Robertson

Ian F Lealman

Ian Lealman

Xin Chen

David Graham Moodie

Michael J Adams

Simon D Perrin

Howard John Wickes

Makoto Okai

David W Smith

Richard Wyatt

Alistair James Poustie

Graeme Douglas Maxwell

Jonathan R Armitage

Alexander Giles Davies

Douglas L Williams

Alwyn John Seeds

Michael Charles Brierley

Paul Rodgers

Edmund Harold Linfield

Peter E Barnsley

Paul C Spurdens

Michael J Harlow

Roger Alyn Payne

Philip J Fiddyment

Christopher David Wood

Paul John Cannard

Simon Ritchie

Cyril Renaud

Ian Douglas Henning

William James Duncan

Robert John Campbell

Gerard Sherlock

John Cunningham

Sukhjiban Dosanjh

Paul Cannard

Gordon Burns

Julie Burton

Planar waveguide apparatus provides a waveguide at least partially overlying a passive buried rib waveguide for coupling optical radiation there between. The overlying waveguide has at least one tapered section, the width of the taper determining the degree of coupling between the waveguides at points along the tapered section. The overlying waveguide may have an active core region. The passive buried rib may have one or more unguided sections below electrically driven regions of the active waveguide to avoid parasitic modes and/or may provide a grating for use as a filter or feedback. Variations include a branched passive waveguide for coupling to two or more overlying waveguides and two or more aligned and active overlying waveguides coupling to one passive waveguide, there being a break in a shared core region of the active waveguides to provide electrical isolation between them.

Coupled waveguide apparatus and structures therefor

The present invention provides a current blocking structure for electronic devices, preferably optoelectronic devices. The current blocking structure comprises a semiconductor material arrangement comprising an n-type ruthenium doped indium phosphide (Ru&#x2014;InP) layer and a first p-type semiconductor material layer wherein the n-type Ru&#x2014;InP layer is less than 0.6 &#x3bc;m thick. The semiconductor material arrangement and p-type semiconductor material layer form a current blocking p-n junction. The current blocking structure may further comprise other n-type layers and/or multiple n-type Ru&#x2014;InP layers and/or intrinsic/undoped layers wherein the n-type Ru&#x2014;InP layers may be thicker than 0.6 &#x3bc;m.

Opto-electronic device

A method of generating radiation comprises: manufacturing a structure comprising a substrate supporting a layer of InGaAs, InGaAsP, or InGaAlAs material doped with a dopant, said manufacturing comprising growing said layer such that said dopant is incorporated in said layer during growth of the layer; illuminating a portion of a surface of the structure with radiation having photon energies greater than or equal to a band gap of the doped InGaAs, InGaAsP, or InGaAlAs material so as to create electron-hole pairs in the layer of doped material; and accelerating the electrons and holes of said pairs with an electric field so as to generate radiation. In certain embodiments the dopant is Fe. Corresponding radiation detecting apparatus, spectroscopy systems, and antennas are described.

Generating and detecting radiation

An optical amplifier has a low polarization dependent gain. The amplifier includes a gain medium including a plurality of adjoining semiconductor layers to provide optical gain wherein the adjoining semiconductor layers define one or more quantum wells for electrons and are operative to provide both direct and indirect electron-hole transitions in the gain medium. A first quantized electron energy level in the conduction band and a first quantized hole energy level in the valence band is located in a first layer. A further first quantized hole energy level in the valence band is located in an adjacent second layer.

An example photodetector includes a waveguide structure having an active waveguide comprising an absorber for converting photons conveying an optical signal into charge carriers conveying a corresponding electrical signal; a carrier collection layer for transporting the charge carriers conveying the electrical signal; and a secondary waveguide immediately adjacent to the carrier collection layer, for receiving the photons to be detected, and which is evanescently coupled to the active waveguide.

Photodetector including multiple waveguides

A detector for electromagnetic radiation in the range 80 GHz to 4 THz comprises a laser light source () an optical modulator () arranged to modulate light from the laser light source () and a filter system () for selecting a defined range of frequencies of the modulated light. The optical modulator is an electroabsorption modulator () with an antenna () which is sensitive to electromagnetic radiation in the range 80 GHz to 4 THz. The signal received by the antenna () modulates the electric field across the electroabsorption modulator (), whereby to modulate the light from the laser light source ().

Terahertz detector

An optoelectronic device has at least a first facet (S), a first waveguide () and a second waveguide (). The waveguides are substantially coincident at the first facet (), such that light travelling along the first waveguide () is reflected into the second waveguide () by the first facet (). The first facet () is formed by precision cleaving. Preferably an etch feature is incorporated in the same mask level as that to define the waveguide core.

Folded cavity of optoelectronic devices

An optical filter is formed from at least two grating located in a waveguide region of a semiconductor optical device. Each grating has a multiple peak optical passband. The gratings are spaced apart in the waveguide region and form an optical cavity having a comb-filter characteristic. The gratings may be located in the active region of an optical gain element and in a preferred example are superstructure gratings (SSGs). A number of filters may be joined together in series.

Optical filters

A semiconductor optical device, for example a laser, has a composite optical waveguide including a tapered, MQW active waveguide in optical contact with a substantially planar, passive waveguide. The fundamental optical mode supported by the composite waveguide varies along the length of the composite waveguide so that, in a laser, the laser mode is enlarged and is a better match to single mode optical fibre. A method for making such semiconductor optical devices is also disclosed.

Method for making optical device with composite passive and tapered

Laser

A semiconductor optical device, for example a laser, has a composite optical waveguide including a tapered, MQW active waveguide in optical contact with a substantially planar, passive waveguide. The fundamental optical mode supported by the composite waveguide varies along the length of the composite waveguide so that, in a laser, the laser mode is enlarged and is a better match to single mode optical fiber. A method for making such semiconductor optical devices is also disclosed.

Optical device with composite passive and tapered active waveguide

Electrical barrier structure for semiconductor device doped with

An optical filter is formed from at least two gratings (102,103) located in a waveguide region (104) of a` semiconductor optical device (101). Each grating has a multiple peak optical passband. The gratings are spaced apart in the waveguide region and form an optical cavity having a comb-filter characteristic. The gratings may be located in the active region of an optical gain element and in a preferred example are superstructure gratings (SSGs). A number of filters may be joined together in series.

Optical comb filters used with waveguide, laser and manufacturing method

Optical clock extraction

Optical switching device with passive input and output stages and active

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Ipswich, United Kingdom

Michael J Robertson