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

TL;DR

This paper demonstrates a subwavelength diffraction grating that performs first-order optical differentiation in transmission, validated by experimental results and an analytical model, with potential applications in photonic devices for beam shaping and optical computing.

Contribution

The paper introduces an experimental demonstration of a guided-mode resonant grating acting as a first-order optical differentiator in transmission, supported by an analytical model.

Findings

Experimental results agree with the analytical model.

The grating performs differentiation in transmission at oblique incidence.

The structure can be used for beam shaping and optical information processing.

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.