Embedding Optical Microcavities in Nanoporous SiO2 Film via Infill Inkjet Printing

• Published in: Advanced photonics research 2022-08, Vol.3 (8), p.n/a
• Main Authors: Obata, Nasim, Mikami, Yuya, Yoshioka, Hiroaki, Oki, Yuji
• Format: Article
• Language: English
• Subjects: inkjet printing; Light; Methods; Nanoparticles; nanoporous films; optical microcavities; organosilica sol; Polymers
• ISSN: 2699-9293; 2699-9293
• DOI: 10.1002/adpr.202200018

The main practical method for fabricating fine optical structures involves mounting them on the surface of a substrate. Although there are other methods for fabricating structures inside materials, none involves the fabrication of optical structures, particularly resonator structures. Thus, a novel method, namely, infill printing in which a resonator structure is embedded in a nanoporous film, is demonstrated to fabricate optical structures. The highly transparent nanoporous film comprises nonspherical SiO2 nanoparticles with a diameter of ≈12 nm. The voids in the nanoporous film are interconnected, facilitating the penetration of polymers exhibiting a diameter of 2–3 nm. By filling the voids in the nanoporous film with a hyperbranched polymer via the printing method, the refractive index can be uniformly controlled, and the optical structures can be embedded. Using infill printing, this is the first time a microdisk resonator exhibiting a reasonable quality factor inside a nanoporous film is successfully demonstrated just as “writing on paper.” A novel and innovative method, “infill printing,” for embedding optical structures in a nanoporous film is established. This method can directly form optical waveguides and microcavities inside of highly transparent SiO2 nanoparticles‐deposited nanoporous films not on a solid substrate such as quartz. It is performed with highly controlled dielectric permeation to the voids in nanoporous films with inkjet technology.