Two‐Photon 3D Optical Data Storage via Fluorescence Modulation of an Efficient Fluorene Dye by a Photochromic Diarylethene

Abstract

3D optical data storage based on two-photon processes provides a mechanism for writing and reading data with less crosstalk between multiple memory layers, due to the quadratic dependence of two-photon absorption (2PA) on the incident-light intensity.[1] This capacity for highly confined excitation and intrinsic 3D resolution affords immense information storage capacity (up to 10 12 bits cm -3). [2] Recently, the use of photochromic materials for 3D memory has received intensive interest because of several major advantages over current optical systems, including their erasable/rewritable capability, high resolution, and high sensitivity. [3] Among the several classes of photochromic materials, diarylethenes with heterocyclic aryl groups are the most promising candidates for applications because of their excellent fatigue resistance, picoseconds switching time, high photoisomerization quantum yields, and absence of thermal isomerization. [4,5] Various optical systems for reading and writing 3D memories using diarylethene derivatives as storage media have been reported, [3] where several methods using fluorescence readout were used to avoid destructive readout. [4] In particular, Jares-Erijman and Irie used Lucifer Yellow I as the donor and bis(thienyl)ethane as the acceptor to build fluorescent molecules and they developed a general conceptual reading/writing system based on fluorescence resonance energy transfer (FRET), where they found that the single-photon fluorescence emission of the donor is reversibly modulated by cyclical transformations of the photochromic acceptor upon irradiation with appropriate UV and visible light. [5,6] This system provided a novel method of using fluorescence to readout the recorded data without simultaneously erasing part of the stored information. However, to the best of our knowledge, modulation of the twophoton fluorescence emission of a dye by a photochromic diarylethene has not been reported as the readout method in a 3D optical-data-storage system. This may be due, in part, to the difficulty in making suitable materials with large 2PA cross sections, high fluorescence quantum yields, and high photostability, in which the emission spectrum properly overlaps the absorption spectrum of one of the isomers of the photochromic diarylethene. In this paper, we demonstrate a novel two-photon 3D optical-storage system based on the modulation of the fluorescence emission of a highly efficient two-photon absorbing fluorescent dye and a photochromic diarylethene. This system is suitable for recording data in thick storage media and providing a non-destructive readout method without exhibiting any apparent fatigue, even after 10 000 readout cycles. The storage medium consists of a commercial available photochromic molecule (diarylethene 1), 1,2-bis(2-methylbenzo[b]thiophen-3-yl)hexafluorocyclopentene, and a specially designed two-photon absorbing dye (2,7-bis[4-(9,9-didecylfluoren-2-yl)vinyl]phenylbenzothiazole (fluorene derivative 2) (Scheme 1). Figure 1 shows the absorption spectra of t...

Two-photon absorption spectra of carotenoids compounds

“…Two-photon absorption (2PA) has been widely exploited in different fields due to its quadratic dependence on the irradiance, which makes it possible to confine the laser excitation to the focal volume. 1 Such feature has led to a large number of technological applications, such as multiphoton fluorescence microscopy, 2 two-photon photopolymerization, 3,4 3D optical data storage [5][6][7] and two-photon photodynamic therapy. 8 In the last decade, p-conjugated molecules have emerged as potential candidates for applications in photonic devices due to its easy handling, environmental stability and structural flexibility.…”

Two-Photon Absorbing Molecules as Potential Materials for 3D Optical Memory

“…The photochromic reactions of the diarylethene derivative 3,4-bis-(2,4,5-trimethyl-thiophen-3-yl)furan-2,5-dione. In 2006 [45,46] and 2007 [47], the same group has reported two-photon resonance energy transfer (RET) from two-photon absorbing fluorene derivatives to the photochromic diarylethene molecule. In the latter report [47], the storage medium used was a polymer matrix of poly(methylmethacrylateco-diethylvinylbenzylphosphonate) PMMA-co-VBP containing diarylethene 7, which was a commercially available photochromic molecule, and two-photon absorbing fluorene derivatives 8 or 9, as shown in Scheme 12.…”

Synthesis, photochromism and fluorescence of new diarylethene bearing a benzofuran unit

“…Photochromic diarylethene compounds have received intense interest because of their potential applications in the area of optoelectronics such as optical recording, photo-switching, and full-color display devices [1][2][3][4][5][6]. Among the numerous reported photochromic compounds, diarylethene derivatives have been achieved much attention because of their outstanding fatigue resistance and thermally irreversible photochromic behavior [7][8][9].…”