Thermal tuning of spectral emission from optically trapped liquid-crystal droplet resonators

0478138 - ÚPT 2018 RIV US eng J - Journal Article
Jonáš, A. - Pilát, Zdeněk - Ježek, Jan - Bernatová, Silvie - Fořt, Tomáš - Zemánek, Pavel - Aas, M. - Kiraz, A.
Thermal tuning of spectral emission from optically trapped liquid-crystal droplet resonators.
Journal of the Optical Society of America. B. Roč. 34, č. 9 (2017), s. 1855-1864. ISSN 0740-3224. E-ISSN 1520-8540
R&D Projects: GA MŠMT(CZ) LD14069; GA MŠMT(CZ) LO1212; GA MŠMT ED0017/01/01
Institutional support: RVO:68081731
Keywords : emission spectroscopy * drops * optical tweezers
OECD category: Optics (including laser optics and quantum optics)
Impact factor: 2.048, year: 2017

Surfactant-stabilized emulsion droplets of liquid crystals (LCs) suspended in water and labeled with a fluorescent dye form active, anisotropic optofluidic microresonators. These microresonators can host whispering gallery modes (WGMs), high-quality morphology-dependent optical resonances that are supported due to the contrast of refractive index between the LC droplets and the surrounding aqueous medium. In addition, owing to the refractive index contrast, such LC emulsion droplets can be stably trapped in three dimensions using optical tweezers, enabling long-term investigation of their spectral characteristics. We explore various combinations of fluorescently dyed LC droplets and host liquid-surfactant systems and show that the WGM emission spectra of optical resonators based on optically trapped LC emulsion droplets can be largely and (almost) reversibly tuned by controlled changes of the ambient temperature. Depending on the actual range of temperature modulation and LC phase of the studied droplet, thermally induced effects can either lead to phase transitions in the LC droplets or cause modifications of their refractive index profile without changing their LC phase. Our results indicate feasibility of this approach for creating miniature thermally tunable sources of coherent light that can be manipulated and stabilized by optical forces.
Permanent Link: http://hdl.handle.net/11104/0274385