Bookham Technology Limited

Kotura, Inc.

Bookham Technologies Plc

Ian Edward Day

Arnold Peter Roscoe Harpin

James Stuart McKenzie

Adrian Petru Vonsovici

George Frederick Hopper

Andrew Alan House

Emma Jane Clarissa Dawnay

An electro-optic device includes a semiconducting layer in which is formed a waveguide, a modulator formed across the waveguide comprising a p-doped region to one side and an n-doped region to the other side of the waveguide, wherein at least one of the doped regions extends from the base of a recess formed in the semiconducting layer. In this way, the doped regions can extend further into the semiconducting layer and further hinder escape of charge carriers without the need to increase the diffusion distance of the dopant and incur an additional thermal burden on the device. In an SOI device, the doped region can extend to the insulating layer. Ideally, both the p and n-doped regions extend from the base of a recess, but this may be unnecessary in some designs. Insulating layers can be used to ensure that dopant extends from the base of the recess only, giving a more clearly defined doped region. The (or each) recess can have non-vertical sides, such as are formed by v-groove etches, A combination of a vertical sidewall at the base of the recess and a non-vertical sidewall at the opening could be used.

Electro-optic modulator

A thermo-optic semiconductor device has one semiconductor region providing an optical waveguide and an adjacent semiconductor region providing a resistive heater between two doped regions, current may be passed through the resistive heater within the adjacent semiconductor region to heat it and thereby vary the optical characteristics of the waveguide.

Thermo-optic semiconductor device

An electro-optic device is disclosed for altering the density of charge carriers within an integrated optical waveguide. The device includes a substrate, and an integrated optical waveguide extending across the substrate with two doped regions being provided such that an electrical signal can be applied across the doped regions to alter the density of charge carriers within the waveguide. The doped regions can each include a plurality of doped areas spaced apart from each other along the length of the waveguide.

Electro-optic device

An isolation device that can be used for providing optical and electrical isolation between areas of an integrated chip. The isolation device includes three doped elongate regions which form diodes which can be connected in series. The isolation device can be used in optical devices or optical attenuators.

Isolation device

A doped slab region is described for use around a ridge waveguide, for controlling the refractive index of the waveguide material. Instead of simply diffusing dopant in from a surface of the slab region adjacent the waveguide, an area of the slab region is etched and dopant diffused in from a side face of the etched region. Thus, the dopant profile is established from a horizontal direction, allowing the profile to be controlled. A simple vertically uniform doping profile can thus be provided, leading to a vertically uniform current density, or an anisotropic wet etch can be applied after the initial etch to provide a profile which concentrates the current density at a selected height in the slab region.

Electro optic modulator

A method of providing a point to point connection between two electrical circuit boards ( ) in which a plurality of pairs of optical transceivers are provided, one transceiver of each pair being formed on a first silicon-on-insulator chip ( ) in electrical contact with a first electrical circuit board ( ), and the other transceiver of each pair being formed on a second silicon-on-insulator chip ( ) in electrical contact with a second electrical circuit board ( ). Each optical transceiver comprises a branched rib waveguide comprising a common stem ( ) and first and second branches ( ) extending from the common stem ( ); a fiber connector ( ) for receiving an optical fiber ( ) in communication with the stem ( ) of the branched rib waveguide; a light source ( ) in communication with the first branch ( ) of the branched rib waveguide; and a light receiver ( ) in communication with the second branch ( ) of the branched rib waveguide. Each pair of transceivers is linked by an optical fiber ( ) connected to the stem ( ) of the branched rib waveguide of the first transceiver and to the stem ( ) of the branched rib waveguide of the second transceiver.

Optical link between electrical circuit boards

Apparatus connecting electrical circuit boards (,, . . . N) so each board can communicate with each other. Each board has an optical circuit, which in turn has a transmitter module (T) and a receiver module (R). The transmitter module (T) has electrical to optical converters (,B) for converting electrical signals into optical signals, a wavelength multiplexer (,) for multiplexing the optical signals into a single optical waveguide (,A), and an optical splitter (,) for dividing the multiplexed signal into a plurality of identical signals for transmission to each of the receiver modules (R). The receiver module (R) has an optical selector (14) for selecting signals from the transmission modules (T), a wavelength demultiplexer (,) for demultiplexing the selected signal into signals each of a different wavelength (&lgr;,. . . &lgr;,), and optical to electrical converters (,B) for converting each of the signals of different wavelengths into an electrical signal.

Connecting a plurality of circuit boards

An integrated optical circuit formed on an optically conductive substrate having light absorbing means comprising one or more doped areas (,) of the substrate where the doping concentration is greater than that of areas of the substrate forming the optical circuit (,) to absorb stray light in the substrate which is not guided by components of the optical circuit.

Growing community of inventors

Headington, United Kingdom

Ian Edward Day