Analog image processing with nonlinear nonlocal flat optics

Abstract

Digital signal processing has revolutionized many fields of science and engineering, but it still shows critical limits, mainly related to the complexity, power consumption, and limited speed of analogue-to-digital converters. A long-sought solution to overcome these hurdles is optical analog computing. In this regard, flat optics has been recently unveiled as a powerful platform to perform data processing in real-time, with low power consumption and a small footprint. So far, these explorations have been mainly limited to linear optics. Arguably, significantly more impact may be garnered from pushing this operation towards nonlinear processing of the incoming signals. In this context, we demonstrate here that nonlinear phenomena combined with engineered nonlocality in flat optics devices can be leveraged to synthesize Volterra kernels able to outperform linear optical analog image processing.

Infrared imaging with nonlinear silicon resonator governed by high-Q quasi-BIC states

“…Additionally, the amplitude, phase change, and directionality of converted frequency emissions can be precisely controlled through the careful design of resonator geometry and the manipulation of resonant responses [5,9,10]. This ability to manipulate light at the sub-wavelength scale combined with minimal absorption allows dielectric resonators to overcome inherently low material nonlinear susceptibilities, and thus realise practical nonlinear applications [15][16][17][18][19].…”

“…Infrared nonlinear imaging, utilising frequency conversion to capture images from infrared in the visible region, has gained growing attention due to its numerous applications in sensing, night vision, and spectroscopy [40]. Relevant works of nonlinear imaging conversion have been demonstrated utilising arrays of nano-resonators, termed metasurfaces [4,18,40,41]. These structures harbour non-local resonances demanding excitation using large irradiance areas needed to satisfy a periodic boundary condition [42].…”