Abstract
Manipulation of the performance of the random lasers from dye-doped nematic liquid crystals with TiN nanoparticles in non-oriented cells is studied. The experimental results show that the introduction of TiN nanoparticles into dye-doped nematic liquid crystals significantly reduces the threshold of random lasing due to the localized surface plasmon resonance of TiN nanoparticles. The emission spectrum of random lasers can be controlled by the shape of the pump spot. The threshold of random lasers increases with the decrease of the length of pump stripe. In order to obtain the emission spectrum with fine discrete sharp peaks, the narrow pump stripe is more effective than the circular pump spot. When the pump area is more like a circle, the emission spectrum is more like an amplified spontaneous emission. The underlying mechanisms of these phenomena are discussed in detail. This study provides a promising platform for designing the high-quality and low-threshold random lasers which can be controlled by the shape of the pump spot.
Highlights
Conventional laser is usually formed by three basic elements: a gain medium, an exciting source, and an optical resonant cavity
In order to obtain the emission spectrum with fine discrete sharp peaks, the narrow pump stripe is more effective than the circular pump spot
The results show that the threshold the random lasers formed by the dye-doped nematic liquid crystals with TiN nanoparticles inofnonNPDDNLC
Summary
Conventional laser is usually formed by three basic elements: a gain medium, an exciting source, and an optical resonant cavity. In the past few decades, a wide range of materials, such as semiconductor [7], π-conjugated [8], human tissues [9], quantum dots [10], metallic nanoparticles [11,12], polymers [13], and liquid crystals (LCs) [14,15,16] have been used to realize random lasers. Metal nanoparticles, such as gold (Au) nanoparticles and silver (Ag) nanoparticles are often used to enhance the performances of random lasers [11,12,17,18,19,20]. In 2019, the recyclable random lasers assisted by metal nanoparticles in DCM dye doped polyvinyl alcohol (DCM-PVA) thin films are studied [20]
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