Tunable whispering gallery modes lasing in dye-doped cholesteric liquid crystal microdroplets

This paper reports the observation of optically pumpedwhispering gallery mode(WGM) lasing emission from dye-doped emulsionmicrodroplets of cholestericliquid crystals (CLCs) suspended in an immiscible aqueous environment. The higher index contrast between the immersion liquid and CLCmicrodroplet contributes to the generation ofWGM resonance so that lasing emission can be realized in the CLCmicrodroplet viatotal internal reflection. TheWGM lasing nature is verified by numerical simulations as well as experiment of size-dependent lasing action. The lasing wavelength depends on therefractive index of the CLCmicrodroplet and can be tuned by varying thetemperature. A tuning range of 9.1  nm within 6 °Ctemperature interval is realized in a 20-μm-diametermicrodroplet. Such atemperature tunable microlaser is promising for applications of flexible photothermic devices.
Source: Applied Physics Letters - Category: Physics Authors: Source Type: research