Nonlinear coloration of photochromic spiropyran solutions

Abstract

Epitaxial BeZnO layers, the candidates for active barrier layers composed of the ZnO/Be x Zn 1−x O quantum well structure, were successfully grown using the hybrid beam deposition method. The Be rate of x in the grown Be x Zn 1−x O layer was estimated to be 0.11. The optical properties caused by the thermal quenching phenomenon of BeZnO, an ultraviolet light emitting material, were studied using the temperature dependence of photoluminescence spectra. Emission of the neutral donor-bound exciton shows a tendency to quench the intensity and extend the spectral width with increasing temperatures. This tendency is related to the phonons generated by the lattice vibration of the host material in BeZnO. These findings led us to conclude that the phonons may be participating in the quenching process.

Experimental characterization of two-photon materials for fast rewritable optical data storage

“…The majority of previously suggested photochromic materials including fulgides [12][13] , spiropyrans 14,15 and diarylethenetype chromophores 16,17 show 2PA cross section σ 2 < 10 2 GM. Literature data on these materials are summarized in Table 1.…”

“…In a disk comprising a large number of data layers, the out of focus 1PA is especially damaging because it strongly reduces the signal to background ratio (SBR). For this reason it was assumed in all previous works [1][2][3][4][12][13][14][15][16][17] that the working frequency is detuned far to the red from 1PA resonance. On the other hand, if the frequency detuning is too large, the 2PA cross section is small and cannot support fast access.…”

“…Over the previous years there have been numerous studies of how to increase the efficiency of simultaneous 2PA in organic chromophores [5][6][7][8][9][10] . A variety of materials for 2PA based volumetric storage has been proposed including fulgides [12][13] , spiropyrans 14,15 and diarylethene-type chromophores 16,17 . All these compounds show 2PA cross section σ 2 < 10 2 GM, which is less than what would be required for practical signal to noise ratio (SNR) for fast writing and readout.…”

Data storage based on photochromic and photoconvertible fluorescent proteins

“…While Hirschberg showed that most of the photochromic molecules in solution can be reversibly phototransformed after the absorption of a single photon at room temperature, other researchers demonstrated that some molecules retain photochromic properties in a rigid medium (Lewis and Lipkin, 1942). Furthermore it was demonstrated that photochromism can be produced by two-photon excitation (TPE) (Mandzhikov et al, 1973). The probability of simultaneous absorption of two photons is proportional to the square of the intensity and, therefore, two-photon excitation only allows the excitation of molecules at the very focus 0168-1656/$ -see front matter © 2010 Elsevier B.V. All rights reserved.…”

Very efficient two-photon induced photo-tautomerization in non-symmetrical phthalocyanines

“…In the late 1980s-beginning of 1990s, the Rentzepis' [1] and other groups [2] brought forward an idea of three-dimensional (3D) re-writable memory, based on photochromic reaction induced by simultaneous two-photon absorption (2PA) [3]. Since the 2PA rate depends quadratically on power density, a tight focusing of laser beam allows one to write a bit (voxel) of information in a diffraction-limited (micron-size) volume in a large number of layers in the depth of a disk with standard DVD dimensions.…”