Research And Modification Of Polymer Host Solid-State Dye Laser Gain Media

Solid-state dye lasers exhibit some attractive features as compared with conventional liquid-dye lasers, such as lack of toxicity and flammability, compactness and low-cost gain medium which, in addition to being an essentially maintenance-free system, make them suitable for applications in field such as medicine, remote sensing and spectroscopy. The development of tunable solid-state dye lasers in which a polymer or sol gel host medium is doped with an appropriate dye is an area of active research.This thesis reviewed the development of tunable lasers, introduced the theory of tunable lasers, and analyzed two ways to prepare of solid-state dye laser. Based on this analysis and research, different concentrations of solid dye samples were obtained via sol-gel process and polymer process. Different laser dyes, such as PM567,PM580,PM597 and DCM, were used to prepare solid–state dyes. The absorption spectrum,fluorescence spectrum,laser spectrum and slope efficiency were measured and analyzed in this thesis. Solid state dyes keep the broad band fluorescence spectrum, the FWHM (Full Wave at Half Maximum) of the fluorescence spectrum is about 30~50nm;Solid state dyes have broud band laser spectrum with the FWHM of ~10nm; The laser efficiency was also studied, and the slope efficiency of the solid state dye lasers was from 10% to 50%.To achieve better thermal properties, such as higher laser damage threshold and higher photostability, different inprovments were used during preparation of the samples. 1) Add small molecules to PMMA host. When small organic molecules (such as ethanol) was added to PMMA host, the samples abtained better thermal conductivity, and got longer lifetime; 2) Copolymer host. When two monomers copolymerized, the solid state dyes can get longer lifetimes; 3) Add Chemical stable additives. Chemical stable additives, such as DABCO were added to eliminate the oxygen molecules, so the laser dyes can got longer lifetimes; 4) Dye mixtures. Dye mixtures were used to produce multicolor output, but also used to improve laser effiencency via energy transfer between different dye molecules.Different modified solid state dyes were prepared, such as Pyrromethene series and Rhodamine series in MPMMA host,P(MMA+HEMA) host and P(MMA+HPMA) host. Optical properties and photostablities of the samples were studied. The experiment results showed that solid state dye lasers in copolymer hosts exhibited better photostability than monomer polymerized. Pumped with a frequency doubled Nd:YAG laser (160mJ/pulse, 10HZ), solid state dye in copolymer P (HEMA:MMA=1:1), got a normalized photostability of 7.80GJ/mol, which was 6 times of the normalized photostability of the PMMA host. Pumped by a frequency doubled Nd:YAG laser (183mJ/pulse, 10HZ), solid state dye in copolymer P (HPMA:MMA=1:9), got a normalized photostability of 5.08GJ/mol.When pump energy reduced to ~17.5mJ (10HZ), solid state dye in copolymer P (HEMA:MMA=1:1), the solid state dye samples got a lifetime more than of 123000 pulses with the normalized photostability of 15.2GJ/mol.