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Observation of stimulated emission from Rhodamine 6G-polymer aggregate adsorbed at foam interfaces
摘要： This paper reports for the first time the observation of stimulated emissions from the gas–liquid interface between two adjacent bubbles in highly ordered foams containing Rhodamine 6 G and surfactant. Stimulated emissions centred at 595 nm were observed when a monolayer of foam (～liquid fraction 0.11), placed on a highly reflective surface, was pumped with a 532 nm continuous wave laser directed along ～45° from the direction perpendicular to the substrate. Additionally, using confocal microscopy and micro-photoluminescence, it was found that the liquid fraction of the foam, the gap between two adjacent bubbles and the incidence angle of the laser are important parameters in guiding the light and promoting stimulated emissions at the interface. The adsorption of the polymer and dye increased the local concentration at the narrowest gaps between pairs of bubbles, which led to the formation of hemispherical micelles-dye agglomerates. The presence of the micelles aggregation caused random scattering induced stimulated emission. These results could have a significant impact on a number of applications, such as photocatalytic conversion at bubble interfaces, where TiO2 can scatter light and hence reaction rates may be increased.
关键词： photocatalysis,Stimulated emission,interface,lasing,microbubbles,foam
更新于2025-09-23 15:22:29
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Tunable laser emissions in freestanding high-Q polymethylmethacrylate microbubbles
摘要： A freestanding dye-doped polymethylmethacrylate microbubble laser based on high-Q whispering gallery mode (WGM) is demonstrated. Low threshold tunable laser emissions are observed in microbubbles with different sizes fabricated by a volumetric pipette. The whispering gallery mode laser emissions in the 944 nm diameter microbubble have a low laser threshold of about 15 μJ pulse?1 and a 0.083 nm free spectral range. The smooth wall of the microbubble ensures a high quality factor of approximately 24 120. In addition, 590 nm–610 nm laser emission is achieved by the reabsorption effect of the dye. This work provides an efficient way to implement a freestanding, easily doped and low cost tunable WGM micro-laser.
关键词： polymethylmethacrylate,laser,microbubbles,whispering gallery mode
更新于2025-09-23 15:19:57
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Mini-review: Laser-induced formation of microbubbles - biomedical implications
摘要： Recent work is summarized that shows how microbubbles may have potential utility in biomedical situations as (i) highly localized generators of intense whitelight in an aqueous environment, (ii) disruptors of matter in aqueous solution, (iii) essential precursors in laser-writing structures on substrates on which biological cells can be spatially aligned, and (iv) mediators in fabrication of hierarchical nano-structures that enhance signals in biological Raman spectroscopy. Indeed, microbubbles generated upon laser irradiation of surfaces have many more ramifications than originally thought, with implications in laser modification of surfaces producing either hydrophilicity or hydrophobicity. Many more possibilities remain to be explored and exploited.
关键词： Raman spectroscopy,biomedical applications,laser-induced formation,microbubbles,surface modification
更新于2025-09-10 09:29:36