Two-photon polymerization initiators for three-dimensional optical data storage and microfabrication

Citation
Bh. Cumpston et al., Two-photon polymerization initiators for three-dimensional optical data storage and microfabrication, NATURE, 398(6722), 1999, pp. 51-54
Citations number
12
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Multidisciplinary,Multidisciplinary,Multidisciplinary
Journal title
NATURE
ISSN journal
0028-0836 → ACNP
Volume
398
Issue
6722
Year of publication
1999
Pages
51 - 54
Database
ISI
SICI code
0028-0836(19990304)398:6722<51:TPIFTO>2.0.ZU;2-1
Abstract
Two-photon excitation provides a means of activating chemical or physical p rocesses with high spatial resolution in three dimensions and has made poss ible the development of three-dimensional fluorescence imaging(1), optical data storage(2,3) and lithographic microfabrication(4-6). These application s take advantage of the fact that the two-photon absorption probability dep ends quadratically on intensity, so under tight-focusing conditions, the ab sorption is confined at the focus to a volume of order lambda(3) (where lam bda is the laser wavelength). Any subsequent process, such as fluorescence or a photoinduced chemical reaction, is also localized in this small volume . Although three-dimensional data storage and microfabrication have been il lustrated using two-photon-initiated polymerization of resins incorporating conventional ultraviolet-absorbing initiators, such photopolymer systems e xhibit low photosensitivity as the initiators have small two-photon absorpt ion cross-sections (delta). Consequently, this approach requires high laser power, and its widespread use remains impractical. Here we report on a cla ss of pi-conjugated compounds that exhibit large delta (as high as 1,250 x 10(-50) cm(4) s per photon) and enhanced two-photon sensitivity relative to ultraviolet initiators. Two-photon excitable resins based on these new ini tiators have been developed and used to demonstrate a scheme for three-dime nsional data storage which permits fluorescent and refractive read-out, and the fabrication of three-dimensional micro-optical and micromechanical str uctures, including photonic-bandgap-type structures(7).