Multiwave coupling in a high-gain photorefractive polymer

Abstract

The characteristics of a new high-gain photorefractive polymer composite with a PNP chromophore are investigated. Competition between beam fanning and two-wave coupling (TWC) is predicted and verified experimentally. The intensity dependence of TWC gain is studied. Higher diffraction order and forward phase conjugation in a TWC geometry are observed and explained.

Thick photorefractive polymer device with coplanar electrodes

“…The device with a thickness of 100 m has a gain coefficient ⌫ of 32.5 cm Ϫ1 under an applied field E 0 ϭ50 V/m. Its gain coefficient ⌫ is higher than that of the sandwich-structure device in the previous study 11 because the electric field vector and the grating vector are collinear each other. The beam-coupling ratio ␥ becomes higher for thicker devices.…”

“…The photorefractive polymer consists of a mixture of a nonlinear optical chromophore, (s)-(-)-N-͑5-nitro-2-pyridyl͒prolinol, a photoconductive polymer, poly ͑N-vinylcarbazole͒, a plasticizing agent, 9-ethylcarbazole, and a sensitizing agent, 2,4,7-trinitro-9-fluorenone, with a weight ratio of 50:33:16:1. 11 To fabricate a͒ Electronic mail: hayasaki@opt.tokushima-u.ac.jp the device, the four materials are first codissolved in chloroform to form a viscous solution. Two aluminum electrodes are then bonded onto glass substrates using an adhesive agent and the glass substrates are separated by 100 m. The viscous solution is casted on the glass substrate with the two electrodes.…”

<title>Simulation of wave mixing in photorefractive polymers</title>

“…al [3] have investigated the characteristics of a new high-gain photorefractive polymer composite of PNP:PVK:ECZ:TNF, 50:33: 16: 1 wt%. Competition between beam fanning and two-wave coupling was predicted theoretically and verified experimentally in [4]. They also observed higher order diffraction and phase conjugation in a twowave coupling (TWC) geometry.…”

“…In most experimental setups, the -2 diffraction order exceeds the critical angle and travels in the waveguide mode [3J. In the same study [4] a series of equations were derived that describe the intemction between the different waves in the material, A1, A., A2, A2, I (beam fanning), in the TWC coupling geometry. In this paper, the equations are presented without derivation The equations that describe the interaction are: …”

Phase-shifting holography using Bragg and non-Bragg orders in photorefractive lithium niobate

“…Higher order generation from self-diffraction is similar to Raman-Nath diffraction [6]. The evolution of higher orders has been explained by Solymar et al [7] and their occurrence during wave mixing in PR polymers [8]. Higher order diffraction has been studied not only for interacting beams but also for images created by an SLM, and has been shown that it is useful for image amplification, reduction and rotation [9].…”