6–10 Jul 2026
University of the Western Cape
Africa/Johannesburg timezone
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Nonlinear wave mixing: from optical elements to artificial neurons

7 Jul 2026, 11:40
20m
Lecture Hall DL1 (University of the Western Cape)

Lecture Hall DL1

University of the Western Cape

Oral Presentation Track C - Photonics Photonics

Speaker

Nikisha Baboolal (University of the Witwatersrand)

Description

The field generated by three-wave mixing in a second-order nonlinear crystal, under suitable approximations, can be described by the product of the two input fields. By controlling the amplitude and phase of the input fields, a single nonlinear crystal can be used to perform many different transformations on the generated field. Here we use difference frequency generation, an effect of three-wave mixing in a nonlinear crystal, to produce different two-dimensional beam shapes by encoding the transmission function of the desired optical element onto one of the input beams. In this way, we demonstrate using a nonlinear crystal as a two-dimensional, virtual optical element. Furthermore, the multiplication of fields in the crystal allows it to exhibit behaviour analogous to that of an artificial neuron, the fundamental unit of a neural network. We classify different Laguerre-Gaussian modes by encoding the mode to be classified on one beam entering the nonlinear crystal, and a phase-only mask composed of different Zernike polynomials with trainable coefficients on the other. This approach of exploiting the multiplication of fields that result from three-wave mixing allows for reconfigurable optics with just a single nonlinear crystal.

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Author

Nikisha Baboolal (University of the Witwatersrand)

Co-authors

Nikita Azevedo (University of the Witwatersrand) Subith Kumar Purakkatteri Meethal (University of the Witwatersrand) Wagner Tavares Buono (University of the Witwatersrand) Angela Dudley (University of the Witwatersrand) Isaac Nape (University of the Witwatersrand) ANDREW FORBES (U. Witwatersrand)

Presentation materials