Lasing and intermode correlation of whispering gallery mode in dye-doped polystyrene microspheres

The advantage of organic materials like polystyrene is their plasticity so that they can be made into any shape. Polystyrene has a rather large refractive index of 1.58 and can be easily doped with the required laser dye and also can be made into spheres of the required size. Fabrication of microspheres was basically carried out by J. Vanderhoff and his assistants at Lehigh University. The host material in all of these samples is polystyrene. Microspheres doped with Bis-MSB, PPO and alpha-NPO dyes were studied with suitable lasers like UV, N-2 and XeCl excimer. We have observed enhanced emission and lasing action at certain wavelengths which correspond to the whispering gallery modes of polystyrene spheres. Characterization of the lasing process in microspheres with respect to their sizes will be presented. The two dimennsional crystalline structure on a periodic array thin film of polystyrene microspheres has been studied by both diffraction and microspopic techniques and will be presented as well.