Csir

University of the Witwatersrand, Johannesburg

University of the Witwaterstrand, Johannesburg

Andrew Forbes

Ihar Anatolievich Litvin

Isaac Nape

Liesl Burger

Angela Dudley

Sandile Ngcobo

Carmelo Rosales-Guzman

Bienvenu Ndagano

Mitchell Cox

Carmelo Guadalupe Rosales Guzmán

Carmelo Guadalupe Rosales GUZMÁN

This invention relates generally to a method and system for hybrid classical-quantum communication. The method comprises transmitting a single photon having a particular quantum state over a communication medium using a quantum mode set; and transmitting a classical light beam over the same communication medium using a classical mode set, wherein the classical and quantum mode sets comprise non-separable modes in common. The non-separable modes in common may be two degrees of freedom of a single photon or classical light and may thus be spatial modes in one or more indexes, and polarisation. The invention relates also to a system to implement the method accordingly.

Method and system for hybrid classical-quantum communication

The invention relates to optical communication methods and systems. In particular, the invention relates to an optical communication method and system which is configured to create a multiplexed beam from an incident beam, wherein the multiplexed beam comprises a predetermined number of spatial modes simultaneously generated and multiplexed together in a fashion that is independent of wavelength. The spatial modes have two degrees of spatial freedom. The multiplexed beam is de-multiplexed downstream from multiplexing thereof in the communication system in a simultaneous fashion independent of wavelength to yield the predetermined number of spatial mode. The modes are used in optical communication as channels or as bits in a bit (de) encoding scheme.

Optical communication method and system

This invention relates to a method of and a system for determining a beam quality factor (VQF) of a beam of light having a transverse electric field that may be scalar, vector, or a combination thereof, wherein the VQF is a measure of the degree of vectorness of the beam of light varying between pure scalar and pure vector. The beam is typically a laser beam, wherein the method comprises receiving an input laser beam to be analysed and splitting the received beam of light into two orthogonal components. A predetermined number of modes or states per orthogonal component is then detected and an on axis intensity of each detected mode or state detected is measured. The measured intensities is then used to calculate the VQF in terms using at least one quantum mechanical entanglement measure.

Method and system for measuring beam quality of a laser beam

Laser apparatus includes an output coupler, a gain medium for generating laser light, a rear optical element, and an input coupler. The input coupler is arranged to direct a pump beam to the gain medium and to define an optical path between the output coupler and the rear optical element. The rear optical element is a spatial light modulator arranged to act as an intra-cavity digital holographic mirror which can be digitally addressed. The spatial light modulator displays selectively a gray-scale image of a hologram thereby to phase-modulate laser light in the cavity, thus making it possible to generate an output laser beam having a desired characteristic. The apparatus includes a computer arranged to generate at least one hologram corresponding to a desired output beam characteristic, and a driver circuit responsive to an output from the computer to generate a corresponding gray-scale image of the hologram on the spatial light modulator.

Method of operating a laser and laser apparatus using intra-cavity digital holograms

The invention relates to an optical resonator, laser apparatus and a method of generating a laser beam inside an optical resonator. The optical resonator () includes an optical cavity () and an optical element () at either end thereof, operable to sustain a light beam () therein, characterized in that each optical element () is a phase-only optical element operable to alter a mode of the beam () as it propagates along the length of the optical resonator (), such that in use the beam () at one end of the optical resonator () has a Gaussian profile while the beam () at the other end of the optical resonator () has a non-Gaussian profile.

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Johannesburg, South Africa

Andrew Forbes