Abstract
The graphene and nanoparticles composites have novel optical and electrical properties. They are widely used in the fields of information sensing, photoelectric conversion and medical diagnosis. Graphene has excellent photoelectric properties and can regulate the random laser properties, but the current composite process of graphene with special structures and metal nanostructures is complicated. Thus, there is still a challenge to effectively reducing the threshold of random laser by using graphene. In this work, the Au/graphene structure is prepared by convenient chemical reduction and adsorption method, and the dye DCJTB is used as the gain medium to form the film by spin coating. The random laser properties of Au nanoparticles and Au/graphene structure are studied, and the mechanism of graphene is analyzed. The results show that the transmission peak of Au/graphene composite is near the photoluminescence peak of gain medium, which promotes the energy level transition of dye molecules. With the addition of graphene into the same gain medium, the scattering frequency of photons in the disordered medium increases, resulting in the enhancement of surface plasmon resonance. The scattering effect and the surface plasmon resonance effect cooperate with each other, showing good random laser threshold, which is reduced from 3.4 μJ/mm<sup>2</sup> to 2.8 μJ/mm<sup>2</sup>. Repeatability and high quality of maser are obtained by repetitively measuring the same sample, showing that the lasing sample has good repeatability and high quality. This study plays a certain role in promoting the application of random laser and realizing the high-performance optoelectronic devices.
Highlights
The inset is the optical image under the pumping
3) (College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, China) ( Received 31 August 2021; revised manuscript received 22 September 2021 )
Summary
图 2 石墨烯的 (a) TEM 图、(b) SEM 图、(c) 红外光谱图和 (d) 拉曼光谱图 Fig. 2. (a) TEM image, (b) SEM image, (c) IR spectra, and (d) Raman spectra of Graphene. 图 2 石墨烯的 (a) TEM 图、(b) SEM 图、(c) 红外光谱图和 (d) 拉曼光谱图 Fig. 2. (a) TEM image, (b) SEM image, (c) IR spectra, and (d) Raman spectra of Graphene. 图 3 (a) Au 纳米颗粒的 TEM 图; (b) Au 纳米颗粒的粒径分布统计图; (c) Au/石墨烯的 TEM 图; (d) Au 纳米颗粒和 Au/石墨 烯的透射光谱以及 DCJTB 染料光致发光光谱. 由图 3(d) 光谱图可以看出, DCJTB 荧光峰位于 602 nm, Au 纳米颗粒的吸收位于 648 nm, Au/石 墨烯结构的吸收位于 576 nm. 相比于 Au 纳米颗 粒, Au/石墨烯复合结构透过率更高且透射峰与 DCJTB 的激射峰更接近, 拥有更好的光谱重叠, 这有利于复合材料与染料间发生能量的转移 [30]. 在激光测量实验中, 采用纳秒激光器 (Continuum, Surelite) 发出的重复频率 10 Hz 的 532 nm 脉冲光作为泵浦光, 光束通过透镜汇聚后所得光斑 直径为 3 mm, 以 45°入射角单脉冲激发样品. 泵浦 能量密度在 1—20 μJ/mm, 通过光纤收集激光信 号并进行研究分析 [26]. 图 4(a) 显示了 Au 纳米颗 粒的随机激光光谱, 激光的中心波长位于 650 nm 处. 图 6 为 Au 纳米颗粒和 Au/石墨烯激射样品 在不同泵浦能量下光谱的半峰宽和峰强度变化图. 图 6 为 Au 纳米颗粒和 Au/石墨烯激射样品 在不同泵浦能量下光谱的半峰宽和峰强度变化图. 对 Au 纳米颗粒激射样品来说, 当泵浦能量超过 4.3 μJ/mm 后, 光谱半峰宽急剧下降, 由 100 nm 降至 13 nm 左右, 且发射强度迅速增加, 样品的激 射阈值约为 4.3 μJ/mm; 对于 Au/石墨烯激射样 μJ/mm
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
