PM567-Doped solid dye lasers based on PMMA

Polymers are a kind of attractive hosts for laser dyes due to their high transparency in both pumping and lasing ranges and superior optical homogeneity. In this paper solid dye samples based on polymethyl methacrylate （PMMA） doped with different concentrations of 1, 3, 5, 7, 8 -pentamethyl-2, 6-diethylpyrromethene-BF2 （PM567） are prepared. The absorption, fluorescence and lasing spectra of the samples are obtained. Wide absorption and fluorescence bands are obtained and a red shift of the maxima of the lasing emission spectra is observed. With the second-harmonic generation of Q-switched Nd：YAC laser （532 nm, -20 ns） pumping the samples longitudinally, the slope efficiencies of the samples are obtained. There is an optimal dye concentration for the highest slope efficiency when the pumping energy is lower than some typical value （-250 mJ）, and the highest slope efficiency 35.6% is obtained in the sample with a dye concentration of 2 × 10^-4 mol/L. Pumping the samples at a rate of 10Hz with a pulse energy as high as 200 mJ （the fluence is 0.2 J/cm^2）, the output energy drops to one-half of its initial value after approximate 15500 pulses and the normalized photostability is 5.17CJ/mol. A kind of solid dye laser which could have some applications is built.

Energy transfer in solid-state dye lasers based on methyl methacrylate co-doped with sulforhodamine B and crystal violet

Laser action in methyl methacrylate （MMA） co-doped with sulforhodamine B and crystal violet dyes was investi- gated. The dye mixture was incorporated into a solid polymeric matrix and was pumped by a 532-nm Nd：YAG laser. Distributed feedback dye laser （DFDL） action was induced in the dye mixture using a prism arrangement both in the donor and acceptor regions by an energy transfer mechanism. Theoretically, the characteristics of acceptor and donor DFDLs, and the dependence of their pulse widths and output powers on acceptor-donor concentrations and pump power, were studied. Experimentally, the output energy of DFDL was measured at the emission peaks of donor and acceptor dyes for different pump powers and different acceptor-donor concentrations. Tuning of the output wavelength was achieved by varying the period of the gain modulation of the laser medium. The laser wavelength showed continuous tunability from 563 nm to 648 nm.

Medium performance effect on the high output energy from a xenon lamp-pumped pyrromethene-567 solid-state dye laser

In order to obtain a high output energy from a xenon lamp-pumped solid-state dye laser, homogeneities of laser mediums and flatnesses of medium faces with different processing treatments are discussed in the paper. The mediums without aging treatment, which are prepared by using a prepolymer process and have diamond-machined end faces to produce the required optical finish, give a highest laser output of 281.9 mJ with 0.215% slope efficiency at 2.0x 10^-4 mol/L. The best medium lifetime is 21 shots to 50% of original output equating 74.6 k J/liter.

A New Organic Up-conversion Laser Dye HEASPS

A new organic dye, trans-4-[p-(N-hydroxyethyl-N-ethylamino)styryl]-N-methyl- pyridinium p-toluene sulfonate (HEASPS) has been synthesized and its structure has been determined. Pumped with a 1064 nm, 50 ps laser pulses, 0.05 mol/L HEASPS/DMF solution showed the two-photon pumped (TPP) output/input efficiency of 9.1% which is higher than that of known TPP laser dyes trans-4-[p-(N-hydroxyethyl-N-methylamino) styryl]-N-methylpyridinium iodide (ASPI) and trans-4-[p-(N-hydroxyethyl-N-methylamino) styryl]-N-methylpyridinium p-toluene sulfonate (HMASPS) at the same experimental conditions.

Characteristics of xenon-lamp pumped pyrromethene 567-doped dye laser based on polymethylmethacrylater

The solid-state medium containing pyrromethene 567 （PM567） in a polymethylmethacrylate polymer host is shown to lase under the flash lamp excitation. The experimental setup is an ordinary industrial product without special design. The bulk transmission losses, the output energy, and the other lasing properties are compared. The medium with the lowest transmission loss, measured to be 0.392 %/cm at 633 nm, gives a laser output of 130 mJ with a slope efficiency of 0.082%.

Photo-Physical Properties of Stilbine-3 (STB-3) Laser Dyes Embedded in Sol-Gel Glasses

Solid-state tunable dye laser materials developed by incorporation of stable laser dye molecules into solid host matrices like polymers, organically modified silicates (ORMOSILS) and porous sol-gel glasses. These materials have technical advantages such as compactness, better manageability and suitability for field measurement. The recent research work with highly porous sol-gel glasses having good transparency in UV-Near UV region used as solid host for solid-state dye laser materials has attracted a great deal of attention because of its high potential utility than polymers. Two different procedure’s are used for incorpoerating the Stilbine-3 (STB-3) laser dyes into porous sol-gel matrices such as dope or dip methods. In dope method dye is mixed at the sol state and drying is carried out afterward;while in dip method matrix is first prepared and the matrix is dipped in desired dye solution. After preparation of these dye embedded sol-gel glasses we studied their spectroscopic properties of using absorption and fluorescence spectroscopy. Along with spectroscopy properties, the studies for longevity or the shelf life and lasing action of these materials were carried out. Laser dye STB-3 incorporated in sol-gel glass samples shows the same result as in methanolic solution.

Synthesis and Characterization of a New Organic Up-conversion Laser Dye HMASPS

A new organic dye, trans-4-[4'-(N-hydroxyethyl-N-methylamino)styryl]-N-methylpyridinium p-toluene sulfonate (HMASPS) has been synthesized and its structure has been determined. Pumped with a 1064 nm, 50 ps laser pulses, 0.05 mol/L HMASPS/DMF solution showed the two-photon pumped (TPP) output/input efficiency of 8.4% which is higher than that of trans-4-[p-(N-hydroxyethyl-N-methylamino) styryl]-N-methylpyridinium iodide (ASPI)(1) at the same pump level.

Comparative Study of Coumarin-120 (C-120) and Stilbine-3 (STB-3) Laser Dyes Doped in Sol-Gel Glasses

In 1967 the first work in solid state dye laser was performed by doping rhodamine dyes in Polymethylmethacrylate (PMMA) materials. Since then some materials like various types of polymers, co-polymers, poly composite glasses have been used as host matrices for doping different laser dyes. Polymers suffer from limited mechanical and thermal stability. Hence glasses can be the alternative hosts. However, because of high processing temperature leading to permanent destruction of dye molecules, the conventional glass preparation technique is not suitable for the introduction of organic laser dyes. This difficulty can be overcome by introducing the laser dye molecules in sol-gel glass which is prepared at low temperature. Recent work with sol-gel glasses shows that these glasses may prove to be better materials compared to polymeric materials because glasses being hard, best optically transparency in Near UV-UV and Visible region and show better photostability. In this research work we reported, comparative study of the photophysical properties of Coumarin-120 (C-120) belonging to 7-aminocoumarin family having two hydrogen atoms attached to the N atom at the 7-position, with Stilbene-3 (STB-3) in three types of HCl catalyzed SiO2 sol-gel matrices prepared by Method I, Method II and Method III respectively.

Laser treatment in 341 patients with exudative agerelated macular degeneration

AIM:To document the prognosis of laser treatment in patients with exudative age-related macular degeneration(AMD).· METHODS:Efficacy of the intervention was evaluated using a before-after method.· RESULTS:A total of 392 eyes of 341 patients with exudative AMD were examined.77.6% had choroideal neovascularisation(CNV).Before the use of indocyanine green(ICG) angiography,occult CNV was detected in only 1.8% of the eyes,but after the use of ICG angiography,this increased to 19.5%(P<0.001).Of the 349 eyes which were followed up,visual acuity had remained stable in 68.2% of the eyes.There was a statistically significant relationship between localisation of lesion and visual acuity changes on pre-and post-laser treatment(P<0.001).Also there was a statistically significant relationship between localisation of lesion and recurrence(P<0.05).The recurrence was less in subfoveal lesions than that in juxtafoveal and extrafoveal lesions.· CONCLUSION:ICG angiography is highly important in the treatment of occult CNV.

Enhanced laser characteristics of pyrromethene 650 using modified PMMA as solid hosts

Solid-state samples based on modified polymethyl methacrylate （MPMMA） with methanol doped with the dye pyrromethene 650 （PM650） axe prepared. The effects of a volume percentage of methanol on the laser characteristics of the sample, including spectra properties, slope efficiency, photostability and tunable properties, are investigated. The broadband dye laser output wavelength is around 655 nm and a highest slope efficiency of 32.23% is achieved. Pumping the samples at a repetition rate of 5 Hz with a pulse energy of as high as 100 mJ （the fluence is 0.26 J/cm2）, the longest lifetime （168000 shots） is obtained in the sample （MMA：methanol=18：2）, and the corresponding normalized photostability reaches 109.19 GJ/mol. When the sample （MMA：methanol=18：2） is placed in a Shoshan-type oscilla- tor, the naxrow-linewidth operation is a continuous tuning range （up to 64 nm）. The results indicate that the laser characteristics of solid-state dyes can be greatly enhanced by using modified PMMA with methanol serving as the solid host.

Two-photon Up-conversion Luminescent Properties of HMASPS and HEASPS in Three Different Polymer Matrices

Three dye-doped polymer rods in different matrices were synthesized in which weak hydrogen bond, strong hydrogen bond and covalent bond existed between the dye and the polymer chain. And the two-photon up-conversion luminescent properties of HMASPS and HEASPS1 in three different microenvironments were studied.

Enhancement of stimulated Raman scattering of acetone and the generation of three-color laser by using fluorescence dye RB

The enhancement of stimulated Raman scattering (SRS) of acetone (C3H6O) and the generation of three color lasers in lasing dye rhodamine B (RB) were reported. The first-order Stokes wave (629.9 nm) of SRS of C3H6O was amplified by 2.83 times than that of pure C3H6O. At the same time, a dye laser of RB at the wavelength from 575 to 598 nm can be generated in a suitable concentration of RB between 3×10-5 and 2×10-4 mol/L. Thus the green pump laser, yellow dve laser, and red Stokes wave concurred.

Effects of lower fluence pulsed dye laser irradiation on production of collagen and the mRNA expression of collagen relative gene in cultured fibroblasts in vitro

Background Lower fluence of 585-nm flashlamp-pumped pulsed dye laser has been successfully used as a nonablative technique in the treatment of wrinkles. The objective of this study was to evaluate the effect of the pulsed dye laser （585 nm） on the production of collagen and the mRNA expression of collagen related gene in fibroblasts in vitro. Methods Cultured fibroblasts were treated with a 585-nm flashlamp-pumped pulsed dye laser （ fluence 3 J/cm^2, 4 J/cm^2, spot size 7 mm, pulse duration 450 12s）. The production of collagen and the mRNA expression of transforming growth factor （TGF）-β1, SMAD2, SMAD3, SMAD4, SMAD7 and type Ⅰ procollagen α1, α2 in fibroblasts were investigated by colorimetry or real time polymerase chain reaction. Results The production of collagen was significantly up-regulated after treatment with a 585-nm flashlamp-pumped pulsed dye laser with a fluence of 3 J/cm^2 （P 〈0.001）. The mRNA expression of TGF- β1, SMAD2, SMAD3, SMAD4, SMAD7 and procollagen I was significantly up-regulated after treatment with a 585-nm flashlamp-pumped pulsed dye laser with a fluence of 3 J/cm^2 （P 〈0.001）. No significant difference of mRNA expression of SMAD2, SMAD3, SMAD4, SMAD7 and type Ⅰ procollagen was found between controls and fibroblasts treated with pulsed dye laser with a fluence of 4 J/cm^2 （P 〉0.05）. Conclusions Lower fluence （3 J/cm^2） pulsed dye laser increased the collagen production in fibroblasts by up-regulating TGF-β1, SMAD2, SMAD3, SMAD4, SMAD7 and type Ⅰ procollagen mRNA expression. These may be the reason it can be effectively used in the treatment of wrinkles.

Photo-physical Characterisation of Novel Organic Dye-doped Solid-state Laser Materials

1 Results The development of tuneable solid-state organic dye lasers is a subject of considerable interest and research activity.Compared to conventional liquid dye lasers they have the advantage of being free of solvent handling,having small size,and being easy to operate.For high-performance solid-state dye lasers highly photo-stable dyes with low quantum yield of triplet formation and low triplet-triplet absorption cross-section in the lasing wavelength region are required.For solid state dye lasers ...

Effect of Medium Acidity and Photostability of 3-（4-Dimethyl- amino-phenyl）-l-（2,5-dimethyl-thiophen-3-yl）-propenone （DDTP）： A New Green Emitting Laser Dye

On the line of a previous work on the spectral properties of some of heteroaryl chalcone, the effect of medium acidity and photoreactivity of 3-（4-dimethylamino-phenyl）-l-（2,5-dimethyl-thiophen-3-yl）-propenone （DDTP） has been investigated in dimethylformamide and in chloromethane solvents such as methylenechloride, chloroform and carbon tetrachloride. The dye solution （ca. 5×10^-4 mol·L^-1 in DMF） gives a good laser emission in the range 470 --560 nm with emission maximum at 515 nm upon pumping by nitrogen laser （λex=337.1 nm）. The laser parameters such as gain coefficient （a）, emission cross section （Cre） and half life energy （E1/2） at maximum laser emission are also determined.

Reverse mode switching of the random laser emission in dye doped liquid crystals under homogeneous and inhomogeneous electric fields

We report the observation of electric field induced random lasing in a dye doped liquid crystal system. This was achieved by using a liquid crystal host with negative dielectric anisotropy doped with laser dye PM 597 in a 75 μm cell with a homeotropic alignment layer. In the absence of an applied field, only amplified spontaneous emission was observed since the liquid crystal orientation was uniform. However, application of a field resulted in a fieldinduced planar-like configuration with local nonuniformity in liquid crystal orientation. This led to random lasing in the energized state(voltage greater than a transition threshold). The onset of lasing occurs by application of either a spatially homogenous or a spatially inhomogeneous electric field across the liquid crystal. The characteristics of the emission spectra as a function of different(i) dye concentration and(ii) applied voltage were investigated using nanosecond pulsed laser excitation at 532 nm. The effects of using an inhomogeneous field were compared to the use of a homogenous field and reported. It is shown that the spatial configuration can be used to alter the emission spectra of the system. The work is used to suggest a new configuration, referred to here as"reverse mode," for liquid crystal-based random lasers. This new configuration may provide additional avenues for their use in commercial devices.

Application of electric field ionization method to detect the high-lying Rydberg states of Eu I

The 4f^76s（~9S）np 8 P J （J = 5/2, 7/2, 9/2） Rydberg series converging to the first ionization limit 4f 7 6s 9 S 4 of the Eu atom using the three-step laser excitation and electric-field-ionization （EFI） method are studied. First, the Eu atom is excited from the 4f 7 6s 2 8 S o 7/2 ground state to the 4f 7 6s7s 8 S o 7/2 state through the 4f 7 6s6p 10 P 9/2 state by the first two dye lasers. Next, it is populated to many higher-n members of the 4f 7 6s（ 9 S）np 8 P J Rydberg series by the third dye laser whose wavelength is scanned within a certain range. Finally, the atom in these higher-n states is ionized by the external pulsed electric field. With the field strength up to 2 kV/cm, we can detect the atom in 4f 7 6s（ 9 S）np 8 P J states with n 40. With the given laser line width, the level energies of Rydberg states with n as high as 72 can be determined. We not only confirm the previous data on the 4f 7 6s（ 9 S） np 8 P J Rydberg series, but also extend the n-value assignment significantly by detecting more states.

Novel phthalocyanine thin film for compact disc recordable

In this paper, the spin-coated thin films of phthalocyanine dye are presented. Absorption spectrum of the thin film shows a comparatively broad absorption in the wavelength range 630 - 770 nm. Optical parameters of the thin film were measured by a spectroscopic ellipsometer system. 5-in CD-R discs made of this dye exhibit good performance with Yamaha 20-speed recorder. Jitters of land and pit are less than 30 ns, and the 3T-11T's signals show very good quality. This dye is a promising recording medium for CD-R with much higher recording speed.