MULTI-SIDED OPTICAL WAVEGUIDE-FED PHOTOCONDUCTIVE SWITCHES
A photoconductive switch and optical transconductance varistor having a photoconductive region e.g. a wide bandgap semiconductor material substrate between opposing electrodes. An optical waveguide is arranged to surround the photoconductive region for directing conduction-inducing radiation into the photoconductive region. And an optical diffusion element is arranged to diffuse/disperse the radiation prior to entering the optical waveguide and into the substrate, for uniformly illuminating the substrate for conduction.
1 . A photoconductive switch comprising:
a wide bandgap semiconductor material substrate;
first and second electrodes in contact with said substrate;
an optical waveguide surrounding exposed facets of the substrate for directing conduction-inducing radiation into said exposed facets of the substrate; and
an optical diffusion element arranged to diffuse/disperse said radiation prior to entering the optical waveguide and into the substrate.
2 . The photoconductive switch of claim 1 ,
wherein the optical waveguide is coated with a reflective coating to reflect radiation into the exposed facets of the substrate.
3 . The photoconductive switch of claim 2 ,
wherein the optical diffusion element is a tapered light pipe connected to the optical waveguide.
4 . The photoconductive switch of claim 1 ,
wherein the first and second electrodes are in contact with said material so that a first triple junction boundary region is formed between the substrate and the first electrode and a second triple junction boundary region is formed between the substrate and the second electrode, and the substrate is located completely within a triple junction region formed between the first and second triple junction boundary regions.
5 . An optical transconductance varistor comprising:
a wide bandgap semiconductor material substrate, whose conduction response to changes in amplitude of incident radiation that is substantially linear throughout a non-saturation region thereof, whereby the material is operable in non-avalanche mode as a variable resistor;
first and second electrodes in contact with said substrate;
an optical waveguide surrounding exposed facets of the substrate for directing conduction-inducing radiation into said exposed facets of the substrate; and
an optical diffusion element arranged to diffuse/disperse said radiation prior to entering the optical waveguide and into the substrate.
6 . The optical transconductance varistor of claim 5 ,
wherein the optical waveguide is coated with a reflective coating to reflect radiation into the exposed facets of the substrate.
7 . The optical transconductance varistor of claim 6 ,
wherein the optical diffusion element is a tapered light pipe connected to the optical waveguide.
8 . The optical transconductance varistor of claim 5 ,
wherein the first and second electrodes are in contact with said material so that a first triple junction boundary region is formed between the substrate and the first electrode and a second triple junction boundary region is formed between the substrate and the second electrode, and the substrate is located completely within a triple junction region formed between the first and second triple junction boundary regions.
9 . A photoconductive switch comprising:
a wide bandgap semiconductor material substrate;
first and second electrodes in contact with said substrate and defining a triple junction region therebetween, with all remaining surfaces of the substrate having a reflective coating to internally reflect conduction-inducing radiation; and
an optical diffusion element arranged to diffuse/disperse said conduction-inducing radiation into the substrate so that the triple junction region may be uniformly illumated and made conductive.
10 . The photoconductive switch of claim 9 ,
wherein the optical diffusion element is a tapered light pipe connected to a face of the substrate.