The photo-neutronrefractive effect

Abstract

Since its discovery in 1966, the photorefractive effect, i.e. the change of the refractive index upon illumination with light, has been studied extensively in various materials and has turned out to play a key role in modern optical technologies like photonics.This article focuses on substances that change their refractive index for neutrons when irradiated with light.

Neutron Optical Beam Splitter from Holographically Structured Nanoparticle-Polymer Composites

“…This is the so-called photo-neutron refractive effect (PNRE) [8,11]. Upon illumination with a spatial light pattern a corresponding refractive-index modulation Án ¼ ð 2 =2ÞÁB occurs that is proportional to the local change ÁB of the coherent scattering length density B.…”

“…In particular, the groups of Tomita et al [14][15][16][17] and Stumpe et al [18,19] have intensively investigated inorganic nanoparticles (SiO 2 and ZrO 2 ) embedded in a photopolymer matrix. They serve as proof of principle for the essential advantages offered by this class of materials for neutron optics over previously used pure photopolymer systems [8,11,20]: the refractive-index modulation can be tuned by the type of nanoparticles, their size, and volume ratio. An additional benefit of including nanoparticles constitutes the increased mechanical stability because shrinkage, which is typical for polymerization processes, is strongly reduced [14].…”

Mirrors for slow neutrons from holographic nanoparticle-polymer free-standing film-gratings

“…Such grating structures can be produced by exploiting the lightinduced change of the refractive index for neutrons in materials-the photo-neutron-refractive effect. 8 Using a conventional holography setup, coherent light beams are superposed at the position of a recording material. Upon illumination with the resulting spatial light pattern, a sinusoidal modulation of b c q and, therefore, also of the refractive index for neutrons occurs in the recording material.…”

A Review of the Optimisation of Photopolymer Materials for Holographic Data Storage

“…As a consequence, not only the optical but also the neutron refractive index may be changed in these cases [86]. The light-induced change of the refractive index for neutrons in materials (the photoneutron-refractive effect) has been exploited to produce diffraction gratings for neutrons by structuring suitable recording materials using holography [87]. The reduction in size of the grating modulation with position, that is, within the layer depth due to the absorption during the recording process, becomes an issue at grating thicknesses of about 100 microns and larger.…”