First-order optical spatial differentiator based on a guided-mode resonant grating

Abstract

We present an experimental demonstration of a subwavelength diffraction grating performing first-order differentiation of the transverse profile of an incident optical beam with respect to a spatial variable. The experimental results are in a good agreement with the presented analytical model suggesting that the differentiation is performed in transmission at oblique incidence and is associated with the guided-mode resonance of the grating. According to this model, the transfer function of the grating in the vicinity of the resonance is close to the transfer function of an exact differentiator. We confirm this by estimating the transfer function of the fabricated structure on the basis of the measured profiles of the incident and transmitted beams. The considered structure may find application in the design of new photonic devices for beam shaping, optical information processing, and analog optical computing.

Analog Optical Spatial Differentiators Based on Dielectric Metasurfaces

“…For practice, simple structures are more preferable, for example by a single layer of resonant metasurface . As an important component for optical processing, the first‐order analog optical spatial differentiator has attracted special attentions . The practicability has been greatly improved in recent works.…”

“…In 2017, Zhu et al has experimentally realized such an optical differentiation device utilizing the angle sensitive excitation of surface plasmonic polariton on metal films . More recently, Bykov et al and Dong et al separately have showed the similar function using subwavelength gratings . However, the plasmonic approach could not be readily extended for other frequency bands primarily limited by the response of material properties.…”

“…By introducing metasurfaces, the combined system became thinner and much compact than conventional ones. This progress sheds light on the potential development of optical analog processors based on metasurfaces.There already exist a few potential application examples about metasurface-based analog optical spatial devices such as differentiators, [18][19][20][21][22][23][24][25][26][27][28] integrators, [18,19,25] and even equation solvers. [29][30][31] The artificial materials utilized in these studies could be classified into three categories: multilayer films, [18,21,22] 1D gratings, [23,24,26] and general 2D metasurfaces.…”

“…This progress sheds light on the potential development of optical analog processors based on metasurfaces.There already exist a few potential application examples about metasurface-based analog optical spatial devices such as differentiators, [18][19][20][21][22][23][24][25][26][27][28] integrators, [18,19,25] and even equation solvers. [29][30][31] The artificial materials utilized in these studies could be classified into three categories: multilayer films, [18,21,22] 1D gratings, [23,24,26] and general 2D metasurfaces. [19,20,25,[27][28][29][30][31] Among these structures, the general 2D metasurfaces with strong modulation flexibility are widely employed to realize the desired spatial operation functions mathematically defined by different Green's functions.…”

“…[25,28] As an important component for optical processing, the first-order analog optical spatial differentiator has attracted special attentions. [18][19][20][22][23][24][25][26][27] The practicability has been greatly improved in recent works. In 2017, Zhu et al has experimentally realized such an optical differentiation device utilizing the angle sensitive excitation of surface plasmonic polariton on metal films.…”