Abstract: A high speed optical switching device includes a waveguide arrangement, incorporating a pn junction, with a large bondpad for the purposes of increasing the capacitance presented by the device. Data and control signals can be input at an input port of the waveguide arrangement, presence of the control signal operating to modify the optical path length of the device for the data signal. By incorporating the device in an interferometer arrangement, or by exploiting a Fabry-Perot cavity of the device, it can be used to transmit the data signal selectively, for instance so as to demultiplex a time multiplexed optical communications signal. The high capacitance provides a very short recovery times so that data rates of 10 GHz and substantially above can be accommodated.

Abstract: An optoelectronic device includes a first n-type epitaxial layer, an active layer having a second epitaxial layer grown on said first layer and a third epitaxial layer of p-type material in the form of a ridge structure selectively grown on or over the active layer, in which a p-n junction is formed in the active layer between a region of p-type material aligned beneath the ridge, and adjacent n-type regions of the active layer, the underlaying first layer being wholly n-type. A method of fabricating such a device involves growing an all n-type planar, forming a dielectric mask thereon, growing by selective epitaxy the ridge structure of p-type material and simulatneously forming the p-n junction by diffusion thereon.