Abstract: A semiconductor optical switching device comprises a passive optical input stage, a matrix stage and a passive optical output stage. The matrix stage incorporates active amplifiers, the switch as a whole being therefore part passive and part active. Control over the switching configuration is provided by electrical inputs to the amplifiers. The matrix stage guides optical signals in a direction transverse to optical signals propagating in the input or output stages. With this configuration, fixed change in direction of the optical paths available to optical signals propagating through the device are provided by splitters, combiners and total internal reflection mirrors.

Abstract: A semiconductor device is disclosed that comprises a base semiconductor portion and, thereon, first and second elevated semiconductor portions separated by a channel. The uppermost surface of the first elevated semiconductor portion carries a metal electrical contact layer and the uppermost of the second a dielectric layer. The surfaces defining the channel are substantially free of metal and dielectric. The structure can be used in a ridge waveguide laser, the first elevated semiconductor portion constituting the ridge. Distributed feedback corrugations may be incorporated in such devices or in other ridge waveguide structures.

Abstract: A semiconductor device comprises a base semiconductor portion and, thereon, first and second elevated semiconductor portions separated by a channel. The uppermost surface of the first elevated semiconductor portion carries a metal electrical contact layer and the uppermost of the second a dielectric layer. The surfaces defining the channel are substantially free of metal and dielectric.The structure can be used in a ridge waveguide laser, the first elevated semiconductor portion constituting the ridge (7", 8").Distributed feedback corrugations may be incorporated in such devices (6), or in other ridge waveguide structures.