We report temperature-induced tuning of whispering gallery mode (WGM) laser emission from a Rhodamine-B-doped polymethylmethacrylate hollow optical fiber. Lasing studies on dye-doped hollow fibers with different radii were carried out with optical pumping using a Q-switched Nd:YAG laser. The observed lasing modes were confirmed as WGM emission with a high quality factor of 7.58×10. The diameter-dependent variation in lasing spectra of these hollow fibers was investigated. A tuning range of 0.44 nm with a sensitivity of 0.011  nm/°C was obtained for the lasing modes by varying the temperature from 25°C to 60°C from a dye-doped polymethylmethacrylate hollow fiber of diameter 305 μm.

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Quality evaluation of fruits and vegetables is of great concern as there is a shortage of unadulterated items on the market. Even unadulterated fruits and vegetables, especially those with soft tissue, cannot be stored for longer times due to physical and chemical changes. Moreover, damage can occur during harvest and in the post-harvest period, while preserving or transporting the fruits and vegetables. This work describes the use of a laser dynamic speckle imaging technique as a powerful optoelectronic tool for the quality evaluation of certain seasonal fruits and vegetables in an Indian market. A simple optical configuration was designed for developing the dynamic speckle imagining system to record dynamic specklegrams of the specimens under different conditions. These images were analysed using a cross-correlation function and the temporal history of specklegrams. The technique can be effectively adapted to the industrial environment and would be beneficial for all stakeholders in the field.