Gec-marconi Limited

Terence P Young

Philip Henry Wisbey

Stuart N Radcliffe

Ian R Croston

Nicholas A Davies

Edwin F Leach

A smoothing layer is provided between the rough etched sides of a channel in a substrate in which an optical waveguiding material is to be produced. Losses are substantially reduced thereby. For a rectangular or rib waveguide, where the sides of the rib are left rough by etching, a smoothing layer is again provided over the rib. The smoothing layer preferably has a refractive index close to or the same as the materials having surface roughness.

Optical waveguides

An optical device comprises a heterojunction bipolar transistor which includes a light guiding layer to which the base contact is made. A ridge is included adjacent to the light guiding layer and acts as the emitter or collector of the transistor, the ridge also defining the lateral extent of the light guiding region. Current injected via the base contact controls the electric field in the region of the ridge and hence the refractive index of the layer controlling the passage of light transmitted along it.

Bipolar transistor including optical waveguide

An integrated optic device includes a waveguide which is curved and includes a section at the bend which is capable of supporting more than one waveguide mode at the opearting frequency. This enables bend angles of greater than 5.degree. be to accommodated without excessive power losses.

Integrated optic waveguide with bend

An optical in-line filter comprises a first waveguide whose output end is coupled to a second, narrower waveguide such that light from the first waveguide of a predetermined waveband or wavebands only is passed to the second waveguide light of other wavebands emerging elsewhere from the open end of the first waveguide.

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Chelmsford, United Kingdom

Terence P Young