Dielectric whispering-gallery-mode resonators are a great tool to entrap electro-magnetic radiation throughout the dielectric’s transparency range[1]. I will discuss hybrid systems which are resonant for both microwave and optical fields and that allow for second order nonlinear effects.
In an efficient resonant system and for strong microwave and optical fields, sum- and difference frequency generation can cascade, leading to optical frequency combs[2]. For the limit of very weak microwaves and only sum frequency generation, coherent conversion of microwave signals allows the quantum state of individual microwave photons to be transferred into the optical domain[3], useful for connecting future superconducting-qubits-based quantum-networks.
1. D.V. Strekalov, C. Marquardt, A.B. Matsko, H.G.L. Schwefel, and G. Leuchs, Journal of Optics 18, 123002 (2016).
2. A. Rueda, ... and H.G.L. Schwefel, Nature 568, 378 (2019).
3. A. Rueda, ... and H.G.L. Schwefel, Optica 3, 597 (2016)
We demonstrate humidity sensors based on optical resonances sustained in sub-wavelength thick dye-doped polymer coatings on reflecting surfaces. As a result of coupling between dye molecular absorption and Fabry-Perot resonances in the air-coating-surface cavity, the absorption spectra of such thin-film structures show a strong resonant peak under certain illumination conditions. These resonances are sensitive to the structural and material properties of the thin-film, metal underlayer and ambient conditions and hence can be used for gas and vapor sensing applications. Specifically, we present our proof of principle experimental results for humidity sensing using a thin-film structure comprising Rhodamine6G-doped polyvinyl alcohol (PVA) films on silver substrates. Depending on the PVA film thickness, dye-concertation and angle of incidence, the resonant absorption peak can undergo either red-shift or blue-shift as RH level increases in the range 20% to 60%. Also, the absorption magnitude at certain wavelengths near to resonance show almost linear reduction which can be used as the sensing signal. Our simulation studies show a very good agreement with the experimental data. The spectral and temporal sensitivity of this thin-film structure is attributed to the changes in the thickness of the PVA layer which swells by absorbing water molecules
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.