Optical gain by a simple photoisomerization process

Abstract

Organic holographic materials are pursued as versatile and cheap data-storage materials. It is generally assumed that under steady-state conditions, only photorefractive holographic media exhibit a non-local response to a light-intensity pattern, which results in an asymmetric two-beam coupling or 'gain', where intensity is transferred from one beam to the other as a measure of writing efficiency. Here, we demonstrate non-local holographic recording in a non-photorefractive material. We demonstrate that reversible photoisomerization gratings recorded in a non-photorefractive azo-based material exhibit large optical gain coefficients beyond 1,000 cm(-1), even for polarization gratings. The grating characteristics differ markedly from classical photorefractive features, but can be modelled by considering the influence of the Poynting vector on the photoisomerization. The external control of the Poynting vector enables manipulation of the gain coefficient, including its sign (the direction of energy exchange), a novel phenomenon we refer to as 'gain steering'. A very high sensitivity of about 100 cm(2) J(-1) was achieved. This high sensitivity, combined with a high spatial resolution, suggests a great technical advantage for applications in image processing and phase conjugation.

Functionalization of the living diatom Thalassiosira weissflogii with thiol moieties

“…Considering the similarity between hydrolyzed TMOS and sodium silicate, the natural source of silica for diatoms, it seems reasonable that both precursors are capable of forming SiO 2 in the presence of silaffins. Condensation of organoalkoxysilanes has been reported in sol-gel science because of the wide diversity of properties that the resulting hybrid materials may offer [10][11][12] . They are typically co-condensed with alkoxysilanes to tailor the crosslinking of the resulting silica network [13][14][15][16][17][18] .…”

Современное Состояние Разработки Светочувствительных Сред Для Голографии (Обзор)

“…В отличие от фоторефрактивных материалов полимерные слои с азокрасителем, испытывающим цис-транс-фотоизоме-ризацию, обеспечивали усиление сигналов в оптическом диапазоне без применения электрического напряже-ния [155]. При этом светочувствительность составляла 0.01 J/cm 2 .…”

Molecular design of photorefractive polymers

“…Thus, usual asymmetric energy transfer occurs in the presence of an external electric field. However, several reports on asymmetric two-beam-coupling gains without the application of an external electric field have been reported for carbazole-based PR polymers, 93,94,111,112 azobenzene derivatives in matrices 113 and carbazole-azobenzene monolithic compound-based PR polymers. [114][115][116] Asymmetric two-beam coupling has also been reported in high T g non-poled PR polymers with carbazole and azobenzene moieties as pendant groups.…”

“…117 A large optical gain coefficient exceeding 1000 cm − 1 was observed in a sol-gel matrix doped with Disperse Red 1 (DR1) in the absence of an external electric field. 113 Asymmetric energy transfer was found to occur in centrosymmetric media. A new model considering the influence of a Poynting vector on a photoisomerization process was proposed to explain the asymmetric two-beam-coupling gain in the sol-gel matrix doped with DR1 in the absence of an external electric field.…”

“…A new model considering the influence of a Poynting vector on a photoisomerization process was proposed to explain the asymmetric two-beam-coupling gain in the sol-gel matrix doped with DR1 in the absence of an external electric field. 113 On the basis of the coupled wave theory for thick hologram gratings proposed by Kogelnik, 36 Kawabe et al 118,119 reported a possible mechanism for this asymmetric energy transfer without charge redistribution in the matrix. They proposed that beam intensity variations, such as asymmetric energy transfer in a PR medium, could be reproduced if a phase difference between the refractive index (phase) modulation φ p and the absorption (amplitude) modulation φ A was 90 degrees.…”