We present a single-layer optical inference system based on nonlinear optical diffraction. In this system, input optical data is superposed with control parameters and then focused into a nonlinear optical crystal leading to second harmonic generation which serves as the output of the system. We demonstrate image classification while utilizing a very low number of degrees of freedom. Importantly, the performance of the system can be tuned by controlling the level of spatial mode mixing in the nonlinear crystal.
Recently an all-optical Quasi Phase Matching (QPM) scheme for High Harmonic Generation (HHG) was introduced in which the pump beam was constructed in the form of an intensity grating whose periodicity could be easily tuned. This was performed using a two-component fundamental beam, superposing a Bessel beam and a Gaussian beam.
Here we present, theoretically and experimentally, a phase matched non-collinear Second Harmonic Generation (SHG) in a doped LiNbO3, using a similar easily tunable scheme.
The phase matching condition depends on both the spatial properties of the fundamental beam and the thermal properties of the medium. We show that a thermally induced phase-mismatch can be compensated by choosing the spatial properties of the pump beam controlled by the SLM, resulting in a phase-matched non-collinear SHG.
Recently an all-optical Quasi Phase Matching (QPM) scheme for High Harmonic Generation (HHG) was introduced in which the pump beam was constructed in the form of an intensity grating whose periodicity could be easily tuned to allow selective enhancement of specific harmonic orders. This was performed using a two-component fundamental beam, superposing a Bessel beam and a Gaussian beam. Here we extend this scheme by constructing the pump as a travelling grating with both controlled periodicity and velocity - utilizing a spatiotemporal modulation, thus allowing both selective harmonic enhancement and fine-tuning of its frequency. Therefore, this scheme can be extremely useful for spectroscopic applications.
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