Photoprogrammable molecular hybrid materials for write-as-needed optical devices B.G. Potter Jr. a, * , K. Simmons-Potter b , H. Chandra a , G.M. Jamison c , W.J. Thomes Jr. c a Materials Science and Engineering Department, University of Arizona, Tucson, AZ 85718, United States b Electrical and Computer Engineering Department, University of Arizona, Tucson, AZ 85718, United States c Sandia National Laboratories, Albuquerque, NM 87185, United States Abstract The application of photosensitive materials to provide immediately configurable optical device functionality in integrated photonic systems has motivated an examination of the unique materials requirements associated with this alternative operational mode. In this case, a reliable photoinduced index change is needed when photopatterning under non-laboratory conditions utilizing compact, integra- ble optical sources. Molecular hybrid thin films, based on inorganic, Group IVA linear-chain polymers, are investigated in terms of exci- tation (writing) wavelength tuning through molecular modification and the influence of environmental conditions and thermal history on the photosensitive response observed. In general, a significant photoinduced refractive index change (with magnitude greater than 10 À2 at 632.8 nm) is found to be retained as the lowest energy absorption band (associated with the Group IVA conjugated backbone structure) is shifted with changes in side-group identity and backbone composition. In addition, the photosensitive response of a representative polysilane composition (poly[(methyl)(phenyl)silylene]) is observed to be strongly dependent on the local atmospheric composition dur- ing photoexposure, a key issue in the effective in-situ patterning of optical structures. Ó 2006 Elsevier B.V. All rights reserved. PACS: 78.66.Qn; 78.40.Me; 78.30.Jw; 42.70.Gi Keywords: Spin coating; Laser–matter interactions; Optical spectroscopy; Absorption; Photoinduced effects; FTIR measurements; Polymers and organics 1. Introduction Photonic device structures produced by the patterned optical exposure of photosensitive materials are now widely recognized as an important means to integrate opti- cal functionality into systems for data transmission, signal manipulation, and physical state sensing. For example, photosensitive Bragg gratings, written directly into the core of optical fiber, are now a widely established technology with broad impact in telecommunications and active pho- tonic systems [1]. More recently, photosensitive materials strategies have been applied in planar architectures for integrated photonic systems [2–4]. In both cases, a funda- mental understanding of the photophysics involved, cou- pled with advances in materials selection and processing, is necessary to optimize the photoinduced refractive index change attained and the subsequent optical performance of these devices. In conventional applications of photosensitivity, optimi- zation of the photowriting process typically focuses on optical sources and exposure procedures available in the laboratory and/or manufacturing environment. Conditions often employ high-power laser systems selected for their wavelength compatibility with the material at hand. In this context, the basic refractive index patterning paradigm is 0022-3093/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jnoncrysol.2006.01.096 * Corresponding author. Tel.: +1 11 520 322 2303; fax: +1 11 520 322 2971. E-mail address: bgpotter@mse.arizona.edu (B.G. Potter Jr.). www.elsevier.com/locate/jnoncrysol Journal of Non-Crystalline Solids 352 (2006) 2618–2627