Non-specular Reflective Optics

TL;DR

This paper explores non-specular wave scattering on 2D discrete surfaces, revealing novel behaviors like negative reflection and critical internal reflection, supported by experimental measurements on a periodic grating.

Contribution

It introduces the concept of non-specular reflection on decorated surfaces and demonstrates experimental validation of these phenomena with theoretical analysis.

Findings

Observation of negative reflection phenomena.

Experimental validation of inverse circular relation for scattering angles.

Excellent agreement between theory and experimental data.

Abstract

Geometrically decorated two-dimensional (2D) discrete surfaces can be more effective than conventional smooth reflectors in managing wave radiation. Constructive non-specular wave scattering permits the scattering angle to be other than twice that of incidence and can result in gross violations of the law of reflection. Hence significant fraction of the phase space becomes accessible. A wide range of novel reflective behaviors ensues; including the phenomenon of negative reflection were energy transport remains on the same side of the normal. Also, at a critical incidence coherent superposition can force both the transmitted and reflected waves to graze the scattering surface thus synergistically reinforcing the diffractive process in a behavior reminiscent of critical internal reflection of ray optics. We experimentally demonstrate the concept with measurements on a one-dimensionally periodic system (grating) where the scattering angle is shown to be an inverse circular function of a function that depends on the diffractive index and the two angles. Excellent agreement is found between experimental data and theory.