Experimental evidence of mixed gratings with a phase difference between the phase and amplitude grating in volume holograms

Abstract

Abstract:The Coupled Wave Theory of Kogelnik has given a wellestablished basis for the comprehension of how light propagates inside a hologram. This theory gives an accurate approximation for the diffraction efficiency of volume phase holograms and volume absorption holograms as well. Mixed holograms (phase and absorption) have been also treated from the point of view of this theory. For instance, Guibelalde theoretically described the diffraction efficiency of out of phase mixed volume gratings. In this work we will show that when using fixation-free rehalogenating bleaches, out of phase mixed volume gratings can be recorded on the hologram at high exposures. This is due to the oxidation products of the developer and the bleaching agent. The effects described theoretically for out of phase mixed volume hologram gratings are experimentally observed.

Temporal evolution of the angular response of a holographic diffraction grating in PVA/acrylamide photopolymer

“…Here also there is asymmetry in the angular response. This type of phenomenon has been widely studied in photographic emulsions [12] and is due to the fact that with high index modulations, not only is there a phase grating but also a small amplitude modulation (absorption coefficient modulation, α) [13,14]. Therefore, in order to carry out a more precise fitting, this should be done based on the mixed gratings theory.…”

Угловая Селективность Амплитудно-Фазовых Голограммных Решеток В Полимерном Материале С Фенантренхиноном

“…В работе [2] такая модель была применена к объемным пропускающим и отражательным голограммам (решеткам) без фазового сдвига. Позднее многие ученые занимались совершен-ствованием данной модели [3,4]. Используемый в данной работе вариант математического аппарата с учетом рас-хождения решеток по фазе был предложен в 2008 г.…”

Parity-time symmetry diffractives implementing unidirectional diffraction–application to optical combiners

“…The balanced spatial alteration of gain and loss regions produces a new type of metamaterials with unique optical characteristics not found in nature [1,2]. The concept of parity time (PT) symmetry borrowed from quantum field theory [3] has been applied to the design of such type of optical structures.…”

“…PT-symmetric materials can produce interesting and unusual optical functionalities. These include double refraction and "nonreciprocal" diffraction [1], or unidirectional Bloch oscillations [2]. In particular, Paladian [4] predicted unidirectional diffraction of waveguide reflective Bragg gratings when they combine balanced periodic modulations of refractive index and loss/gain which was later theoretically analyzed in details showing the complete reflectiveness of such Bragg gratings when probed from one side.…”