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We propose a novel, directional fiber-optic level meter based on a micro-air-bubble drifted in a liquid-core fiber-Fabry-Perot-interferometer which can detect non-horizontal state of structure/object and also be able to discriminate the inclining to clockwise/counterclockeise directions.

We proposed a novel, miniature and ultrasensitive fiber-optic thermometer based on an air-micro-bubble drifted in a liquid-core-fiber Fabry-Perot-interferometer. The proposed sensor has an ultrahigh sensitive and linear spectral response with -9.0 nm/°C in temperature measurement.

This paper reports for the first time an electrically and thermally controllable nanoparticle (NP) random laser in a well-aligned dye-doped liquid crystal (DDLC) cell. Experimental results show that the random lasing emission is attributed to the amplification of the fluorescence via the multiple scattering of the randomly distributed NPs in the diffusion rout of the well-aligned DDLC cell. The random laser can be electrically and thermally controlled by varying the applied voltage and cell temperature, respectively. As the applied voltage is increased, the orientational change of the LCs from homogeneous to homeotropic texture decreases the dye absorption and thus the spontaneous fluorescence emission, resulting in the decrease of the random lasing emission. The random lasing intensity decreases with increasing temperature at the nematic phase and dramatically increases after the nematic→isotropic (N→I) phase transition. The result in the former stage is attributed to the decreases in the absorption and thus in the spontaneous fluorescence emission for the laser dyes because of the decrease in the order of the laser dyes with increasing temperature at the nematic phase. The result in the latter stage results from the significant decrease of the loss because of the disappearance for the strong leakage of the scattering fluorescence light through the boundaries of the LCs and the glass substrates after the N→I phase transition. Moreover, the anisotropy of the random lasing is crucially determined by two factors: the anisotropies in the spontaneous emission and the leakage of the scattering fluorescence light.

We propose a dynamic, directional, and miniature fiber-optic level meter based on a micro-air-bubble drifted in a liquid-core fiber Fabry-Perot interferometer. The proposed in-fiber level meter can detect the non-horizontal/horizontal state of an object/structure and also be able to discriminate the test structure inclining to the clockwise or counterclockwise directions by measuring the spectral responses of the proposed optical fiber device. Dynamic drifting of the micro air bubble in the tilted condition has been recorded which investigates the drifted directions correlated closely with the tilted directions in the fiber level meter.