Tunable integrated optical filters based on sapphire microspheres and liquid crystals

Gilardi, Giovanni and Yilmaz, Hasan and Murib, Mohammed sharif and Asquini , Rita and d'Alessandro, Antonio and Serpengüzel, Ali and Beccherelli, Romeo (2010) Tunable integrated optical filters based on sapphire microspheres and liquid crystals. In: Silicon Photonics and Photonic Integrated Circuits 2. Proceedings of SPIE-The International Society for Optical Engineering (7719 ). Spie-Int Soc Optical Engineering. ISBN 9780819481924

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We present an integrated optical narrowband electrically tunable filter based on the whispering gallery modes of sapphire microspheres and double ion-exchanged channel BK7 glass waveguides. Tuning is provided by a liquid crystal infiltrated between the spheres and the glass substrate. By suitably choosing the radii of the spheres and of the circular apertures, upon which the spheres are positioned, arrays of different filters can be realized on the same substrate with a low cost industrial process. We evaluate the performance in terms of quality factor, mode spacing, and tuning range by comparing the numerical results obtained by the numerical finite element modeling approach and with the analytical approach of the Generalized Lorenz-Mie Theory for various design parameters. By reorienting the LC in an external electrical field, we demonstrate the tuning of the spectral response of the sapphire microsphere based filter. We find that the value of the mode spacing remains nearly unchanged for the different values of the applied electric field. An increase of the applied electric field strength, changes the refractive index of the liquid crystal, so that for a fixed geometry the mode spacing remains unchanged.

Item Type: Book Section
Subjects: 600 Tecnologia - Scienze applicate > 620 Ingegneria e attivita' affini
Depositing User: Matteo Viola
Date Deposited: 08 Mar 2013 10:05
Last Modified: 22 Mar 2013 13:45
URI: http://eprints.bice.rm.cnr.it/id/eprint/4544

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