Fabrication and assessment of mechanically flexible 1D photonic crystals and active planar waveguides

Thin-film optics is a key technology for the fabrication of miniaturized photonic devices, spanning from optical waveguides and photonic-integrated-circuits for optical signal processing, to multi-layered resonant structures and cavities for the confinement and spectral selection of the optical field. Active optical waveguides and photonic crystals are among the most versatile examples. One further step to add versatility to thin-film photonic structures involves the use of flexible materials. In fact, by adding mechanical flexibility to the rigid photonic systems, the range of applications greatly expands. However, passing from rigid to flexible substrates requires the development of suitable fabrication protocols, to preserve the optical and spectroscopic properties of the systems under mechanical deformation. We present the RF-sputtering fabrication of 1D photonic crystals and active Er3+ planar waveguides deposited on polymers and ultrathin flexible glass substrates. The structures deposited on ultrathin flexible glass show interesting results in terms of both optical and mechanical properties, making RF-sputtering a promising and scalable technique to fabricate flexible photonic devices [1,2]. Moreover, we report on the spectroscopic study of a 1D photonic crystal, fabricated via RF-sputtering on a flexible thermosetting polymer, in different bending conditions. Acknowledgements: This research is supported by the projects: FESR-PON 2014-2020 BEST4U ARS01_00519; CNR-PAS "Flexible Photonics" (2020-2022); NAWA PPN/IWA/2018/1/00104; MIUR-'Departments of Excellence' L 232/2016; ERC-H2020 PAIDEIA GA 816313; "nuovi Concetti, mAteriali e tecnologie per l'iNtegrazione del fotoVoltAico negli edifici in uno scenario di generazione diffuSa" CANVAS and NAWA-MAECI Canaletto (2022-2023). References: [1] A.Carlotto, et.al., Proc. SPIE 12142, pp. 1214206 (2022); doi:10.1117/12.2621281 [2] A.Carlotto, et.al., Ceramics International, (2023); doi:10.1016/j.ceramint.2023.03.012