Thick photorefractive polymer device with coplanar electrodes

Abstract

We propose a structure of a photorefractive polymer device. An electric field is applied to the device in plane so as to coincide with the direction of a grating formed by two writing beams. This structure permits us to fabricate a thick photorefractive polymer device with a high optical gain. The maximum thickness we fabricated was 600 μm. We investigate the device performance using a two-beam coupling experiment and demonstrate high-beam-coupling gain in the thick device. We also describe position dependence of the photorefractive effect for an apical electrode structure.

Photorefractive Organic Materials and Applications

“…Hayasaki et al proposed a new electrode structure where both the anode and the cathode are on the same glass plate [138]. They named this configuration "coplanar electrodes" and the geometry is reproduced in Fig.…”

“…They named this configuration "coplanar electrodes" and the geometry is reproduced in Fig. 1 [138] vector (K) which maximizes the photorefractive response. The drawback of that geometry is the very limited active area due the high electric field that needs to be applied, requiring a small spacing between the electrodes.…”

“…An analytical solution of the first-order Fourier component of the space-charge field was derived by Cui and coworkers [138]. Using a similar approach, Yuan and coworkers derived a kinetic differential equation for the formation of the space-charge field as a function of the light intensity and the grating spacing, first for the case of no trapping, and in later papers [139][140][141][142] for the cases of deep traps (high and low density) and to consider moving gratings driven with a periodic force at an arbitrary frequency.…”

“…This approach was first presented by Ostroverkhova and Singer [102] and later modified by Kulikovsky and coworkers [106]. the more realistic situation of having at least two well-defined trapping levels: one regarded as a deep trapping level, already considered in Schildkraut's work, and a second regarded as a shallow trapping level; a situation already observed experimentally in a variety of photorefractive polymers [26,82,113,138,143].…”

Photorefractive polymers for holography

“…Electrode/film thicknesses varying from 100 to 600 µm were tested with this configuration and values of gain peaked at 35 cm −1 for the 600 µm sample. The limiting parameter of this device was the small active area, constraining the angles of incidence and beam sizes used and restricting the applicability of this geometry to display oriented devices …”