Papers by Keyword: Lasing

Abstract: We report a hybrid hetero p-n junction between Zinc Oxide (ZnO) microspheres and p-GaN thin film or poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS). ZnO microspheres, which have high crystalline quality, were synthesized by ablating a ZnO sintered target with focused pulsed laser at high fluence. Recent investigation has demonstrated that ZnO microspheres had high optical property and laser actions in the WGM (whispering gallery mode) from the microshperes under pulsed laser irradiation. In this study, we fabricated a hybrid hetero p-n junction between ZnO microspheres and p-GaN or PEDOT:PSS, and both p-n junctions with p-GaN or PEDOT:PSS had a good rectifying characteristic. In the case of p-GaN, electroluminescence was observed under forward bias.

Abstract: Continuously tunable random laser basing on rhodamine 6G was achieved. Wavelength tuning was implemented by wedge-shaped sample shift relatively to the pump beam. The physical base of the tuning method is gain band shift caused by reabsorption. We ascertained that two medium thickness ranges of significantly different tune efficiency exist. The lasing characteristics of the laser were investigated depending on active medium and pump beam parameters. The feedback formation mechanisms in the random lasers of different thickness were analyzed.

Abstract: We investigated the lasing spectra of multiple scattering active media based on solid polymer solutions of rhodamin 6G with embedded scattering silica particles of mean diameter 500nm. Lasing in these samples appears without any cavity and arises even in rather small active volume 0.05*0.5*0.5mm3. In a thick sample positive feedback for lasing is provided mainly by multiple scattering of light. In a thin sample the feedback is provided both by multiple scattering of light on the particles and light reflection from the sample surface. It is found that the lasing spectra peak wavelength can be varied within 13nm by varying sample thickness in a range 0.1 -1.65mm. A method of continuos laser tuning by wedge-like sample shift with respect to the pump beam is proposed. The presented results are aimed at the development of a new type of microlaser.