Two-Photon Patterning of Inorganic and Hybrid Materials

One strategy is to fabricate a template structure using polymeric material (thus, using the same chemistry as described in Sects. 5.2 and 5.3) and back-fill or coat this structure with inorganic materials. For example, surface modification, followed by electroless deposition of Ag [217-219] or Cu [220], or by chemical reduction of Au solutions by surface functionalities [220], has been used to obtain metallized structures, while infiltration of polymeric photonic bandgap-type structures with Ti(0 Pr)4 solution, followed by hydrolysis and calcination, has been used to obtain highly refractive inverted Xi02 structures [221]. Au has also been deposited onto multiphoton-patterned matrices of biomaterials [194]. 

The use of organic dyes with high 2PA cross section in the writing of inorganic structures has been much more limited however, dyes i.l and i.2 (Fig. 21) have been used to write wires of group-10 metals, especially Ag. In this case, donor-substituted dyes, such as q.l, are unsuitable, since the ground state molecule, as well as the excited state, is capable of reducing Ag . However, acceptor-substituted quadrupolar dyes, such as i.l and i.2. 

Organic-silica hybrid materials have been used for multi-photon microfabrication. These include the acrylate-functionalized oligosiloxanes known as ORMOCERs, which have been polymerized by radical processes using conventional IP radical iniatitors, such as c.2 [221,234]. Commercial poly(dimethylsiloxane)-based resists containing vinyl and Si-H functionalities use two different 2PA-induced processes hydrosilylation catalyzed by the photodecomposition products of Cp PtMes (Cp = ti -methylcyclopentadienyl) and radical initiation by c.4 (Fig. 13) [235]. The former process was complicated by thermally-induced polymerization. 

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