A blue random laser based on solid waveguide gain films with silver nanoparticles (NPs) and SiO<sub>2</sub> NPs is demonstrated. Located surface plasmon resonance (LSPR) property and multiple scattering are proven playing an important role simultaneously.
After the multiphoton ionization of sodium-argon mixture, time-resolved atomic emission spectrum is used to experimentally study the unusual phenomenon of the obviously different broadening between Na D<sub>1</sub> and D<sub>2</sub> lines spectra. The primary reason for the unusual broadening of Na D<sub>2</sub> line is that the spectral line of Ar I 588.9 nm overlays with Na D<sub>2</sub> line (589.0 nm) after ionization, and the serious self-absorption on Na D<sub>2</sub> line is the secondary reason. Although there is difference of population between 3<sup>2</sup>P<sub>3/2</sub> and 3<sup>2</sup>P<sub>1/2</sub> states, the experiment result demonstrates that the difference between Na D lines in radiation channel will not affect the broadening of spectral profile.
Recently, the optically pumped rare gas lasers have been attracted extensive attention. Rare gas laser systems with Ne (2p<sup>5</sup>3p), Ar (3p<sup>5</sup>4p), and Kr (4p<sup>5</sup>5p) atoms have been investigated. However, there are sparse studies based on Xe. In this work, new phenomena, intensive mid-infrared amplified spontaneous emissions (ASEs), are found after two-photon excitation of Xe from the ground state to the 6p[1/2]<sub>0</sub> state. Simultaneously, substantial 6p[1/2]<sub>1</sub> atoms are populated. The thresholds of ASE peak 1 and the generation of 6p[1/2]<sub>1</sub> atoms are both about 1.5 mJ. It indicates that there should exist the relationship between these two phenomena. The ASE signals show broadband spectra. Therefore, it must be yielded by the superposition of Xe<sub>2</sub>* excimer transitions. The mid-infrared ASEs lead to excimers correlating to the 6s’[1/2]<sub>1</sub> enormously generated. Then these excimers dissociate to produce substantial 6p[1/2]<sub>1</sub> atoms. Under some circumstance, the ratio of the 6p[1/2]<sub>1</sub> to 6p[1/2]<sub>0</sub> atoms reaches about 80%. It indicates that the 6p[1/2]<sub>0</sub> atoms strongly tend to decay through the emissions between the excimer states. Using these emissions, continuous-tunable mid-infrared laser with metastable Xe can be promisingly produced.