Self-written waveguides in a dry acrylamide/polyvinyl alcohol photopolymer material

Abstract

For the first time it is demonstrated that permanent optical waveguides can be self-written in a solid acrylamide/polyvinyl alcohol photopolymer material. The novel (to our knowledge) technique used to prepare the polymeric medium used is described. It is demonstrated that the resulting waveguides formed can be used to guide different wavelengths. A standard theoretical model is used to predict both the evolution of the light intensity distribution and the channel formation inside the material during the exposure. The experimental results and the numerical simulations are compared, and good agreement is obtained.

Holographic waveguides in photopolymers

“…Their wide potential in photonics and communications have been long and extensively studied. There are interesting applications and development in diffractive optics [2,3], optical communications [4], photonic crystal [5], holographic data storage [6], sensors [7], solar concentrators [8], wearable eyeglasses [9] and waveguides [10,11]. This last application can be designed as a tool or supporting technology for more complicated displays, such as photovoltaic concentrators or see-through eyeglasses [12].…”

“…Previously, waveguides have been fabricated using different holographic architectures [14][15][16]. Additionally, waveguides can be self-written in these materials [10,11]. The last possibility is the fabrication by holographic transmission architecture [17].…”

Optical Trajectory Manipulations Using the Self-Written Waveguides Technique

“…The rate of production of the excited state photosensitizer is given by ka(x, y, z, t) (s -1 ). The effects of dye diffusion DA(x, y, z, t) are assumed negligible, due to the relatively slow diffusion of the large dye molecules, compared to the other process taking place [20,21]. It is also assumed that during the exposure the dye recovery is negligible, i.e., kr  0, being much faster than the recovery rate [22,23].…”

“…The photopolymer material, as used in this work [13], consists of several components: A binder (Polyvinyl Alcohol-PVA), a monomer (Acrylamide-AA), a cross-linker (Bisacrylamide-BA) and an electron donor (Triethanolamine-TEA). The dye used here is Eosin-Yellowish (EY) (C20H6Br4Na2O5), which is photo-sensitive to green light at wavelength λ = 532 nm, and acts to initiate the polymerization process [12,21,37]. A Gaussian beam at this wavelength emerges from the SM fiber inside the photosensitive material, see figure 1.…”

“…However eventually, as can be seen in figure 4(a) the light begins to focus to create a narrow channel that changes the beam intensity shape confirming the generation of a SWW. Therefore, the Gaussian beam is self-focused and self-trapped in the optical waveguide channel along the direction of propagation inside the sample [3,7,21,40,41]. Thus, the diffraction of the light is balanced by the self-focusing effect and self-trapping occurs.…”