Random lasing from granular surface of waveguide with blends of PS and PMMA

Xuanke Zhao,Dawei Wang,Zhaoxin Wu,Xun Hou,Shixiong Liang,Shuya Ning

doi:10.1364/oe.19.016126

Abstract

Lasing from a planar waveguide with the blend of Polystyrene(PS): Poly-methylmethacrylate(PMMA) doped with tris(8-hydroxyquinolinato)aluminum(Alq(3)) and 4-(dicyanomethylene)-2-tert-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran(DCJTB) was investigated. Due to phase separation of the blend of PS:PMMA during the solvent evaporation process, a waveguide with granular surface was obtained, which has 2D island-like nanostructures with diameters ranging between 200 and 400 nm and heights at about 25 nm. Pumped by a YAG laser with wavelength of 355 nm, a significant random lasing was observed. Compared to the amplified spontaneous radiation (ASE) of planar waveguides with only PMMA or PS doped with Alq3:DCJTB prepared under the same conditions, the lasing threshold of the former is decreased by about 5 times, and the full width at half maximum (FWHM) is reduced to 1.7 nm from 12~15 nm. Our experiments show a promising method to achieve lower threshold for organic lasers.

Highlights

Random lasers, which are formed by strong scattering in disordered gain systems, have attracted much attention in both theoretical and experimental areas for their potential applications as micrometer-scale laser sources, as remote sensors, and in optical storage [1,2,3,4,5,6], because of their extreme simplicity, low cost and robustness in operation
Our experiments show a promising method to achieve lower threshold for organic lasers
Our demonstration showed a simple and easy way to achieve organic random lasing with the lower threshold for the further applications

Summary

Introduction

Random lasers, which are formed by strong scattering in disordered gain systems, have attracted much attention in both theoretical and experimental areas for their potential applications as micrometer-scale laser sources, as remote sensors, and in optical storage [1,2,3,4,5,6], because of their extreme simplicity, low cost and robustness in operation. Many optical materials were reported for the random lasing, such as powders of solid-state luminescent and laser crystals [7,8,9], liquid laser dyes with scatterers [10,11], polymeric films with and without intentionally introduced scatterers [12,13,14,15], ZnO scattering films and nanoclusters [2,16],dye-infiltrated opals [13,17], porous media infiltrated with liquid crystals with dyes [18,19,20] and many others[21,22,23]. In this Letter, we reported random lasing emission form a waveguide with a granular surface made of spin-coated Polystyrene(PS): Poly-methylmethacrylate(PMMA): tris(8hydroxyquinolinato)aluminum(Alq3):4-(dicyanomethylene)-2-tert-butyl-6(1,1,7,7tetramethyljulolidyl-9-enyl)-4H-pyran(DCJTB) blend film. By spin-coating process, without doping nanoparticles in host materials, we obtained a 2D granular nanostructure with diameters of about 200-400 nm and heights of about 25 nm due to phase separation of PS/PMMA during the solvent evaporation process. Compared to the waveguides with only PS or PMMA doped by dyes, the waveguide of the blend of PS:PMMA doped by dyes exhibited excellent random lasing action with lower threshold

Sample preparation and experimental setups

Results and discussion

Conclusion