Qinetiq Limited

Spi Lasers UK Limited

Qubitekk, Inc.

Philip Michael Gorman

Paul Richard Tapster

Ewan David Finlayson

John M Heaton

Brian Sinclair Lowans

Christophe Andre Codemard

Michael J Kane

David Maurice Taylor

David Mark Benton

John Michael Heaton

Michael John Kane

Apparatus for providing optical radiation (), which apparatus comprises a laser diode (), a pulse generator (), and a modulator (), wherein: the pulse generator () is configured to emit picosecond pulses; the modulator () is configured to emit nanosecond pulses; the laser diode () has a first terminal () and a second terminal (); the pulse generator () is connected to the first terminal (); and the modulator () is configured to bias the laser diode () below a lasing threshold () of the laser diode (), and the apparatus being characterized in that: the modulator () is connected to the second terminal (); the pulse generator () comprises a semiconductor junction () connected to a differentiator (); the semiconductor junction () is such that electric current flowing through the semiconductor junction () can be turned off more quickly than it can be turned on; and the differentiator () is such that a step change that occurs when the electric current flowing through the semiconductor junction () is turned off is converted to an electrical pulse, thereby gain switching the laser diode () such that it emits an optical pulse () having an optical pulse width () less than 10 ns.

Apparatus and method for providing optical radiation

Random number generation apparatus () is described that comprises a threshold detector () and an electrical noise generator (). The electrical noise generator () has at least two channels (-) and each channel is arranged to generate an electrical noise signal. The threshold detector (), which may comprise a digital input-output (DIO) card, is arranged to periodically compare this electrical noise signal with a threshold and to provide a binary data output that indicates whether the threshold has been exceeded. Each channel of the electrical noise generator comprises at least two amplifiers (-) electrically connected in series that preferably provide a gain of 50,000 or more. Use of the random number generation apparatus () for quantum cryptography applications is also described.

Apparatus and method for generating random numbers

A non-linear optical device includes a frequency-conversion waveguide and first and second input waveguides. The longitudinal axes of the input waveguides are inclined to that of the frequency-conversion waveguide such a first transverse mode is excited in the latter at the input frequency in operation of the device. The frequency-conversion waveguide supports a second transverse mode at an output frequency of the device, such that the phase velocity of the second transverse mode at the output frequency is substantially equal to that of the first transverse mode at the input frequency, thus providing phase-matching by balancing the effects of chromatic and modal dispersion.

Non-linear optical device

An electro-optic waveguide polarization modulator () comprising a waveguide core () having first and second faces defining a waveguide core plane, a plurality of primary electrodes () arranged at a first side of the waveguide core plane and out of said plane, and at least one secondary electrode () arranged at a second side of the waveguide core plane and out of said plane, wherein the electrodes () are adapted in use to provide an electric field having field components () in two substantially perpendicular directions within the waveguide core () so as modulate the refractive index thereof such that electromagnetic radiation propagating through the core () is converted from a first polarization state to a second polarization state.

Electro-optic waveguide polarisation modulator

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Malvern, United Kingdom

Philip Michael Gorman