Optically tunable random lasing from azo-dye-doped polymer dispersed liquid crystal in capillary tubes

This study demonstrated the optically tunable random lasing from azo-dye-doped polymer dispersed liquid crystal (PDLC) in capillary tubes, in order to expand new applications for this device. The azo-dye-doped PDLC was prepared in glass capillaries with different core diameters, and the random lasing thresholds of these samples were measured respectively. The spectra of random lasers were measured with increasing the intensity of ultraviolet radiation. The experimental results show that the random laser threshold measurements of different core diameter capillary samples (100 μm, 300 μm, 500 μm) are 11.8 μJ/pulse, 8.6 μJ/pulse and 13.2 μJ/pulse. The experimental results also show that as the intensity of ultraviolet radiation increases (from 0 mW/cm2 to 150 mW/cm2), the random laser intensity decreases gradually, and the FWHM of the spectrum becomes wider. And the random lasing showed similar properties under the UV beam with different polarized directions during the optical tuning process. Our work verifies the possibility to fabricate miniature laser devices in cylindrical confinement structures, and extends the application scope of PDLC.