A ring-shaped random laser in momentum space

Abstract

A color-switchable random laser is designed through directly coupling random laser with a commercial optical fiber. By using a simple approach of selectively coating the random gain layer on the surface of fiber, the red and yellow random lasers are respectively achieved with low threshold and good emission direction due to the guiding role of optical fibers. Moreover, the unique coupling mechanism leads to the random lasing with ring-shape in momentum space, indicating an excellent illuminating source for high-quality imaging with an extremely low speckle noise. More importantly, random lasing with different colors can be flexible obtained by simply moving the pump position. The results may promote random lasers' practical applications in the fields of sensing, in vivo biologic imaging, high brightness full-field illuminating. Experimental MethodsThe fabrication process of the fiber source is illustrated in Fig. 1a. The typical gain materials used in this experiment are: 4-(Dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidin-4-yl-vinyl) -4H-pyran(DCJTB, Tokyi Chemical Industry) and Pyrromethene567 (PM567, Sigma). The fabricated process of the fiber source is simply supplied as follows. First, polydimethylsiloxane (PDMS, n = 1.41) solution is mixed with cross-linking solution with the ratio of 1:10. Then, TiO 2 nanoparticles are dispersed in the dye-doped acetone solution (DCJTB at 1.5 mg mL -1 or PM567 at 1.25 mg mL -1 ) to obtain TiO 2 dispersion with a concentration of 0.9 mg mL -1 . The dye-doped TiO 2 dispersion and PDMS are mixed at a volume ratio of 1: 5 in an ultrasonic tank for 15 min and then vacuum them for 40 min to remove the air bubble. Finally, the mixture is dipped onto a clean fiber (TAIHAN Fiber Optics) to flow naturally. The length of the fiber is about 60 mm, the core diameter is 50 μm and the diameter of the cladding is 125 μm. The refractive indexes of the core and cladding layer are 1.54 and 1.52, respectively. The sample is placed in a drying oven at 80 °C for 3 hours to complete the cross-linking polymerization and drying. After cooling to room temperature, a fiber source is realized. Random lasers with different colors can be fabricated by coating different dye polymers at different locations on the surface of the fiber. And the polymer film with different thicknesses can be fabricated by controlling the dipping times.Acs Nano, 2017, 11. 36.

Anderson Localization Enabled Spectrally Stable Deep-Ultraviolet Laser Based on Metallic Nanoparticle Decorated AlGaN Multiple Quantum Wells

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Random Laser Spectral Fingerprinting of Lithographed Microstructures

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Ca2+/Sr2+/Ba2+ dependent phase separation, nanocrystallization and photoluminescence in fluoroaluminosilicate glass

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