Abstract: A semiconductor device for use in an optoelectronic integrated circuit; the device comprising: a group four substrate, a waveguide, and a group III/V multilayer stack; wherein the group III/V multilayer stack comprises a quantum component for producing light for the waveguide; wherein the waveguide comprises a material with a deposition temperature below 550 degrees Celsius and a refractive index of any value between 1.3 and 3.8.

Abstract: A semiconductor device comprising a silicon substrate on which is grown a <100 nm thick epilayer of AlAs or related compound, followed by a compound semiconductor other than GaN buffer layer. Further III-V compound semiconductor structures can be epitaxially grown on top. The AlAs epilayer reduces the formation and propagation of defects from the interface with the silicon, and so can improve the performance of an active structure grown on top.

Abstract: A semiconductor device comprising a silicon substrate on which is grown a <100 nm thick epilayer of AlAs or related compound, followed by a compound semiconductor other than GaN buffer layer. Further III-V compound semiconductor structures can be epitaxially grown on top. The AlAs epilayer reduces the formation and propagation of defects from the interface with the silicon, and so can improve the performance of an active structure grown on top.

Abstract: A semiconductor device is disclosed comprising: a substrate having a surface comprising germanium; a layer of gallium on said surface; and a layer of gallium arsenide on the gallium covered surface. The semiconductor heterostructure of gallium arsenide on germanium is fabricated by the steps of: protecting by a shutter a surface comprising germanium in an environment having a partial pressure of arsenic less than 10?8torr; epitaxially growing a layer of gallium on the said surface immediately after exposure of said surface; and epitaxially growing a layer of gallium arsenide on the gallium covered surface.

Abstract: A semiconductor device comprising a silicon substrate on which is grown a <100 nm thick epilayer of AlAs or related compound, followed by a compound semiconductor other than GaN buffer layer. Further III-V compound semiconductor structures can be epitaxially grown on top. The AlAs epilayer reduces the formation and propagation of defects from the interface with the silicon, and so can improve the performance of an active structure grown on top.

Abstract: A semiconductor device comprising a silicon substrate on which is grown a <100 nm thick epilayer of AlAs or related compound, followed by a compound semiconductor other than GaN buffer layer. Further III-V compound semiconductor structures can be epitaxially grown on top. The AlAs epilayer reduces the formation and propagation of defects from the interface with the silicon, and so can improve the performance of an active structure grown on top.

Abstract: A semiconductor device is disclosed comprising: a substrate having a surface comprising germanium; a layer of gallium on said surface; and a layer of gallium arsenide on the gallium covered surface. The semiconductor heterostructure of gallium arsenide on germanium is fabricated by the steps of: protecting by a shutter a surface comprising germanium in an environment having a partial pressure of arsenic less than 10?8torr; epitaxially growing a layer of gallium on the said surface immediately after exposure of said surface; and epitaxially growing a layer of gallium arsenide on the gallium covered surface.

Abstract: A method and apparatus for transporting three or more radio signals of the same frequency, such as multiple input multiple output (MIMO) radio signals, over optical fiber on a single optical carrier using a phase quadrature double sideband frequency translation technique is disclosed.

Abstract: An example photodetector includes a waveguide structure having an active waveguide comprising an absorber for converting photons conveying an optical signal into charge carriers conveying a corresponding electrical signal; a carrier collection layer for transporting the charge carriers conveying the electrical signal; and a secondary waveguide immediately adjacent to the carrier collection layer, for receiving the photons to be detected, and which is evanescently coupled to the active waveguide.

Abstract: A semiconductor photodetector is disclosed which can have a high responsivity, high saturation power, and high bandwidth. The photodetector comprises a waveguide structure comprising: an active waveguide comprising an absorber for converting photons conveying an optical signal into charge carriers conveying a corresponding electrical signal; a carrier collection layer for transporting the charge carriers conveying the electrical signal; and a secondary waveguide immediately adjacent to the carrier collection layer, for receiving the photons to be detected, and which is evanescently coupled to the active waveguide. The secondary passive waveguide layer in the photodetector epitaxial structure enables the use of fast carrier transport material to generate high intrinsic bandwidth and travelling wave techniques associated with a scheme of evanescent coupling to increase the responsivity, saturated output power and bandwidth.

Abstract: A method of transmission of radio signals over all types of graded-index multimode fibre is provided. The method comprises launching optical radiation into the core of the multimode fibre with a specified restricted launch to allow multiple trans-verse mode lasers transmitters to be used in low cost radio over fibre links. The launch technique allows a reduction in modal dispersion and modal interference, thus greatly improving the transmission performance of radio over fibre signals over multimode fibre as well as reducing system impairments such as outages and link failures.