Organic laser dyes rhodamine

Laser action in organic dyes was discovered independently by Sorokin et al. [8.45] and Schafer et al. [8.46] in 1966. Since then, several hundreds of dyes have been shown to have suitable properties, to greater or lesser degrees, for use as laser media. One of the most common laser dyes is Rhodamine 6G dissolved in methanol or ethylene glycol. The complex structure of organic dyes is illustrated in Fig.8.18, where the formula for Rhodamine 6G is shown. 

Small organic molecules doped into polymer binders have also been employed in DEED devices. Coating is done using inexpensive solution techniques. A commonly used polymer is polyvinylcarbazole [50-52], which is a hole transport material with moderate mobility. Polysilanes have also been used as hole transport agents [53]. Common laser dyes may be employed as the emissive molecular dopant, for example coumarins [50, 51], rhodamines [50] or pyrans [51, 53]. Similar considerations of energetics and concentration apply to doped polymers as to small molecule dopant-host systems the dopant should provide the lowest energy site for the exciton and concentration quenching should be minimized. 

Liquid Organic solvent (dye-chromophore) Rhodamine dye (Rh6G) 580-610 Flashlamp laser pumping... 

The strongest commonly observed absorption bands in organic molecules are exhibited by laser dyes such as rhodamine 6G, a xanthene dye with a rigid chromophore which exhibits e ax 10 L/mol cm at 5300 A (Chapter 9). Its fluorescence lifetime t is in the neighborhood of 5 ns (depending on solvent), and is dominated by t,ad because (2f nearly unity under conditions in which stimulated emission is suppressed. At the other extreme, for Ij in an inert solvent like cyclohexane is about 7 x 10 L/mol cm for the spin-forbidden -V B ITou transition. In accordance with Eq. 8.50, T d for this transition is in excess of 10 /xs. Little I2 -> emission can be seen in solution,... 

Organic Dye Lasers. Organic dye lasers represent the only weU-developed laser type in which the active medium is a Hquid (39,40). The laser materials are dyestuffs, of which a common example is rhodamine 6G [989-38-8]. The dye is dissolved in very low concentration in a solvent such as methyl alcohol [67-56-17, CH OH. Only small amounts of dye are needed to produce a considerable effect on the optical properties of the solution. 

The first, and still the most commonly used, of the tunable lasers were those based upon solutions of organic dyes. The first dye laser was developed by Sorokin and Lankard 05), and used a "chloro-aluminum phthalocyanine" (sic) solution. Tunable dye lasers operating throughout the visible spectrum were soon produced, using dyes such as coumarins, fluorescein, rhodamines, etc. Each dye will emit laser radiation which is continuously tunable over approximately the fluorescence wavelength range of the dye. 

Fig. 12.12 Photograph of a Coumarin 6 solution excited by the organic laser (a) and photoluminescence of the marker dyes Coumarin 152, Coumarin 6 and Rhodamine 6G measured with utilization of an organic solid-state laser as excitation source (b).

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