Whispering gallery mode study of phase transition and shape change in liquid crystal droplets

Neogi, Arkalekha (avtor), Zaplotnik, Jaka (avtor), Ravnik, Miha (avtor), Muševič, Igor (avtor)

We demonstrate that the Whispering Gallery Mode (WGM) lasing spectroscopy is a versatile high resolution tool to study the structure of interfaces of liquid crystalline (LC) droplets immersed in an immiscible fluid, such as water. The eigenfrequencies of WGMs in spherical microcavities are very sensitive to the refractive index profile in the nanometer thin interfacial region. This makes it possible to detect interfacial phenomena and temperature change in LC droplets with interferometric accuracy. We use 10–30 µm diameter droplets of a nematic liquid crystal labeled with a fluorescent dye and floating in water as an optical microcavity that sustains the WGMs. At the isotropic–nematic transition we observe wetting of the droplet's interface by a nanometer-thin layer of paranematic LC. Just below this transition, we observe red-shift and strong fluctuations of WGM spectra just before spherical droplet elongates into a fiber. The experiments are modeled with Finite-Difference Time-domain (FDTD) analysis of WGMs in nematic droplet and we find very good qualitative agreement.

• Jezik: Angleški jezik
• Ključne besede: Whispering Gallery Mode spectroscopy, liquid crystals, liquid crystal droplets
• Vrsta gradiva: Članek v reviji
• Tipologija: 1.01 - Izvirni znanstveni članek
• Organizacija: FMF - Fakulteta za matematiko in fiziko
• Status publikacije: Objavljeno
• Različica publikacije: Objavljena publikacija
• Leto izida: 2026
• Št. strani: Str. 604-615
• Številčenje: Vol. 22, iss. 3
• PID: 20.500.12556/RUL-178234
• UDK: 538.9
• ISSN pri članku: 1744-6848
• DOI: 10.1039/D5SM01126D
• COBISS.SI-ID: 264538627
• Datum objave v RUL: 21.01.2026

Gradivo je del revije

• Naslov: Soft matter
• Skrajšan naslov: Soft matter
• Založnik: Royal Society of Chemistry
• ISSN: 1744-6848
• COBISS.SI-ID: 23741223

Licence

• Licenca: CC BY 4.0, Creative Commons Priznanje avtorstva 4.0 Mednarodna
• Povezava: http://creativecommons.org/licenses/by/4.0/deed.sl
• Opis: To je standardna licenca Creative Commons, ki daje uporabnikom največ možnosti za nadaljnjo uporabo dela, pri čemer morajo navesti avtorja.

Sekundarni jezik

• Jezik: Slovenski jezik
• Ključne besede: WGM spektroskopija, tekoči kristali, tekočekristalne kapljice

Projekti

• Financer: EC - European Commission
• Številka projekta: 884928
• Naslov: Light-operated logic circuits from photonic soft-matter
• Akronim: LOGOS