Abstract
In this paper, magnetically tunable random lasing from a polymer dispersed liquid crystal (PDLC) in a capillary was achieved by means of doping with magnetic nanoparticles (MNPs). We experimentally explored the effects of the concentration of MNPs and the amplitude and direction of the magnetic field on the emission properties of random lasing, such as threshold, envelope of the emission spectrum, and intensities. The related mechanism was also investigated theoretically. Experimental results also showed that weakly tuned effects appeared from the sample with a polymer or pure liquid crystal (LC) doped with MNPs in comparison with PDLCs. Our research would provide an additional way to achieve tunable compact LC-based lasers.
Highlights
Magnetically tunable random lasing from a polymer dispersed liquid crystal (PDLC) in a capillary was achieved by means of doping with magnetic nanoparticles (MNPs)
A magnetically tunable random laser from a PDLC doped with MNPs in a capillary was demonstrated
Experimental results showed that the envelope center of the random lasing presented a blue-shift with increasing MNP concentration
Summary
In 1994, Lawandy et al first verified the phenomenon that stimulated radiation amplification can be achieved in disordered gain media through experiments, namely random lasing. At present, the applications of random lasing have far reaching impacts on other disciplines, for example, photonics and biology, and scholars have conducted multiple studies in this regard. Generally, random lasing is generated in several ways, for example, from laser crystal powder, laser dye doped in a particle suspension, or a powdered semiconductor, such as ZnO, TiO2, Fe3O4, etc. With the advance in materials, the random lasing behavior has been found in liquid crystal (LC) systems or LC-based systems. Thanks to the reorientation of liquid crystal molecules under external excitation, such as force, temperature, electric and magnetic field, and light, laser radiation based on liquid crystal systems can be influenced and modulated by external excitation. Thanks to the reorientation of liquid crystal molecules under external excitation, such as force, temperature, electric and magnetic field, and light, laser radiation based on liquid crystal systems can be influenced and modulated by external excitation. Ye et al studied the electromagnetic and thermal modulation of random lasing in dye-doped liquid crystal systems.. In 2017, Mur et al studied magnetic field tuning and whispering cavity mode lasing emission of a ferromagnetic nematic liquid crystal microdroplet structure.. LC-based lasers have been prepared in optical fibers or two-dimensional capillary structures for various application scenarios. LC-based lasers in capillaries with a polymer dispersed liquid crystal (PDLC) (capi-PDLC) doped with ferromagnetic MNPs were prepared, and the random lasing properties of the prepared samples were explored experimentally. The intensity of lasing with the magnetic field in the parallel direction is stronger than that of the magnetic field in the vertical direction
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