Deasy, KieranSediq, Khalid N.Brittle, StuartWang, TaoDavis, FrankRichardson, Tim H.Lidzey, David G.2016-05-242016-05-242014-08-27Deasy et al. (2014) A chemical sensor based on a photonic-crystal L3 nanocavity defined in a silicon-nitride membrane, Journal of Materials Chemistry C, Vol. 2, Iss. 41, pp. 2-412050-7526http://dx.doi.org/10.1039/C4TC01320Dhttps://dspace.lib.cranfield.ac.uk/handle/1826/9909The application of a silicon-nitride based L3 optical nanocavity as a chemical sensor is explored. It is shown that by adjusting the thickness of an ultra-thin Lumogen Red film deposited onto the nanocavity surface, the fundamental optical mode undergoes a progressive red-shift as the layer-thickness increases, with the cavity being able to detect the presence of a single molecular monolayer. The optical properties of a nanocavity whose surface is coated with a thin layer of a porphyrin-based polymer are also explored. On exposure of the cavity to an acidic-vapour, it is shown that changes in the optical properties of the porphyrin-film (thickness and refractive index) can be detected through a reversible shift in the cavity mode wavelength. Such effects are described using a finite difference time-domain model.enAttribution-Non-Commercial 3.0 Unported (CC BY-NC 3.0) You are free to: Share — copy and redistribute the material in any medium or format, Adapt — remix, transform, and build upon the material. The licensor cannot revoke these freedoms as long as you follow the license terms. Under the following terms: Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. Information: Non-Commercial — You may not use the material for commercial purposes. No additional restrictions — You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits.Article