Mode Selective Up-conversion Detection with Turbulence

Abstract

We experimentally study a nonlinear optical approach to selective manipulation and detection of structured images mixed with turbulent noise. Unlike any existing adaptive-optics method by applying compensating modulation directly on the images, here we account for the turbulence indirectly, by modulating only the pump driving the nonlinear process but not the images themselves. This indirect approach eliminates any signal modulation loss or noise, while allowing more flexible and capable operations. Using specifically sum frequency generation in a lithium niobate crystal, we demonstrate selective upconversion of Laguerre-Gaussian spatial modes mixed with turbulent noise. The extinction reaches ~40 dB without turbulence, and maintains ~20 dB in the presence of strong turbulence. This technique could find utilities in classical and quantum communications, compressive imaging, pattern recognition, and so on.

Large-scale Ising emulation with four body interaction and all-to-all connections

“…We use a portion of the input pump beam to monitor the power fluctuation which is <5% during a whole day operation. The transverse FWHM of the pump beam is 2.6 mm incident on the SLM (Santec SLM-100, 1440 × 1050 pixels, pixel pitch 10.4 × 10.4 μm) at a 50°incidence angle 54,56 . Initially, a random binary phase mask with phase value 0 or π is uploaded onto the SLM.…”

“…The total supported spin number, on the other hand, is less in practice, due to the optical perfections. Although this study considers only SH generation, it can be straightforwardly extended to other nonlinear processes, such as sum-frequency generation, difference-frequency generation, four-wave mixing, for other interesting Ising machines [54][55][56][57]70 . Such nonlinear optical realizations of Ising machines could contribute as supplements for big data optimization and analyses that remain challenging for classical supercomputers or forthcoming quantum machines but with a limited number of qubits.…”

Large-scale Ising Emulation with Four-Body Interaction and All-to-All Connection

“…At the present, the maximum number of accessible spins is about 1 million, and can be further increased by using modulators with more pixels or combining multiple modulators. While this study considers only second-harmonic generation, it can be straightforwardly extended to other nonlinear processes, such as sum-frequency generation, difference-frequency generation, four-wave mixing, for other interesting Ising machines [59][60][61][62]73 . Such nonlinear optical realizations of Ising machine could contribute as supplements for big data optimization and analyses that remain challenging for classical super-computers or forthcoming quantum machines but with a limited number of qubits.…”

“…Equations ( 4)-( 5) can in principle be solved by using split-step Fourier and adaptive step-size methods. However, the numeric solutions consume significant computational time and resources that increase exponentially with the spin number 61 , whose inefficiency calls for the present optical realization. Only under the conditions of phase matching (∆κ = 0), undepleted pump approximation, and negligibly small diffraction terms in Eqs.…”

Super-resolution optical classifier with high photon efficiency

“…In this letter, we propose and demonstrate a nonlinear optical technique, based on mode-selective SF generation [20,21,26,27], for super-resolution optical classification using photon counting. By using a spatial-light modulator (SLM) to create optimized pump for SF generation, light sources spaced well below the Rayleigh criterion can be faithfully resolved.…”