Dresden 2020 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 15: Postersession KFM

KFM 15.14: Poster

Thursday, March 19, 2020, 16:00–18:30, P2/1OG

Tunable coupling of Whispering Gallery Mode resonators by temperature regulated contraction of Liquid Crystal Elastomers — •Osman Karayel, Simon Woska, Roman Oberle, Pascal Rietz, and Heinz Kalt — Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany

Applications in various fields of optics like communications or sensors can be realized using Whispering Gallery Mode (WGM) resonators, which grant in particular on micron scales exceptionally high quality factors. Evanescent fields in the surrounding medium allow for coupling of WGM resonators in close proximity. Coupling of WGM resonators and especially the ability to vary their coupling strength by tuning the gap between them is essential for advanced applications.

We present WGM resonators processed by Direct Laser Writing on Liquid Crystal Elastomer (LCE) substrates to achieve adjustable coupling gaps. LCE has the ability to reversibly contract in one direction for rising temperature, which can be utilized to move resonators placed on top of the LCE towards each other. It is possible to produce LCE substrates on sub-millimeter scales matching the dimensions of the WGM resonators, which potentially allows for on-chip applications.

We demonstrate tunable coupling of two WGM resonators purely by temperature variation of the LCE substrate. In fiber-based transmission-spectroscopy measurements of the resonators the effects of coupling are reflected by modifications of the spectral features. These changes get more pronounced with rising temperatures due to observably smaller gaps between the resonators.