Integration in analog optical computing using metasurfaces revisited: toward ideal optical integration

In this paper, we introduce a modified optical integrator based on suitably designed metamaterial blocks. The integration is performed on an impinging wave pattern as it propagates through these blocks. So far, various metamaterial-based optical integrators have been implemented with appropriate performance in the case of zero-DC input signals. However, these integrators suffer from low accuracy when fed by signals rich in low-frequency contents. The latter property arises from truncation of low-frequency contents of the input wave in the Fourier domain. To solve this shortcoming, we propose a new metasurface-based structure which reflects low-frequency parts of the input signal in the Fourier domain. This subtracted part is then measured in the input and compensated in the detected output signal. The numerically simulated output responses verify superior performance of the proposed structure compared to conventional metamaterial-based optical integrator in the case of input signals with considerable low-frequency contents. These findings may lead to remarkable achievements in light-based plasmonic signal processors at nanoscale, which can replace their bulky conventional dielectric lens-based counterparts. (C) 2017 Optical Society of America