Laser performance of Coumarin 540A dye molecules in polymeric host media with different viscosities: From liquid solution to solid polymer matrix

11 pages, 12 figures, 3 tables.-- PACS: 42.70.Hj; 42.55.Rz; 42.55.Mv; 66.20.+d; 78.55.Bq; 78.55.KzPhotophysical parameters and lasing properties of Coumarin 540A dye molecules are studied in solutions of increasing viscosity, from liquid solutions in 1,4-dioxane to solid solutions in poly(methyl methacrylate). The fluorescence quantum yield and lasing efficiencies decrease as the viscosity of the solution increases, reflecting the strong influence of the rigidity of the medium on the radiative processes. The photodegradation mechanisms acting on the fluorophores are analyzed by following the dependence of laser induced fluorescence and laser output on the number of pump laser pulses. The fluorescence redistribution after pattern photobleaching technique is used, and Fick's second law is applied to study the diffusion of dye molecules in the highly viscous polymer solutions. The diffusion coefficients of the dye molecules as a function of the increased viscosity of the medium are determined.This work was supported by the Spanish CICYT Project MAT94-0757.Peer reviewe

A borane laser

© 2015 Macmillan Publishers Limited. Emission from electronically excited species forms the basis for an important class of light sources-lasers. So far, commercially available solution-processed blue-emitting laser materials are based on organic compounds or semiconductor nanocrystals that have significant limitations: either low solubility, low chemical-and/or photo-stability and/or uncompetitive prices. Here we report a novel and competitive alternative to these existing laser materials that is based on boron hydrides, inorganic cluster compounds with a rich and diverse chemistry. We demonstrate that solutions of the borane anti-B 18 H 22 show, under pulsed excitation, blue laser emission at 406 nm with an efficiency (ratio of output/input energies) of 9.5%, and a photostability superior to many of the commercially available state-of-the-art blue laser dyes. This demonstration opens the doors for the development of a whole new class of laser materials based on a previously untapped resource for laser technology-the boranes.Peer Reviewe

Highly photostable solid-state dye lasers based on silicon-modified organic matrices

11 pages, 13 figures, 4 tables.-- PACS: 42.55.Rz; 42.60.FcWe report on the synthesis, characterization, and physical properties of modified polymeric matrices incorporating silicon atoms in their structure and doped with laser dyes. When the silicon-modified organic matrices incorporated pyrromethene 567 (PM567) and pyrromethene 597 (PM597) dyes as actual solid solutions, highly photostable laser operation with reasonable, nonoptimized efficiencies was obtained under transversal pumping at 532 nm. At a pump repetition rate of 10 Hz, the intensity of the laser emission remained at the level or above the initial lasing intensity after 100 000 pump pulses in the same position of the sample, corresponding to an estimated accumulated pump energy absorbed by the system of 518 and 1295 GJ/mol for PM567 and PM597, respectively. When the pump repetition rate was increased to 30 Hz, the laser emission of dye PM567 decreased steadily and the output energy fell to one-half its initial value after an accumulated pump energy of 989 GJ/mol. Dye PM597 demonstrated a remarkable photostability, and under 30 Hz pumping the laser emission from some samples remained stable after 700 000 pump pulses in the same position of the sample, corresponding to an accumulated pump energy of 17 300 GJ/mol. Narrow linewidth operation with tuning ranges of up to 31 nm was obtained with both pyrromethene dyes when some of the samples were incorporated into a grazing-incidence grating oscillator.This work was supported by Project Nos. 7N/0100/02 of the Comunidad Autónoma de Madrid ( CAM) and MAT2004- 04643-C03-01 of the Spanish CICYT. One of the authors (O.G.) thanks the MEC for awarding her a Ramón y Cajal scientific contract. Another author (D.A.) thanks CAM for a predoctoral scholarship.Peer reviewe

Circularly polarized laser emission induced in isotropic and achiral dye systems

The production of efficient, tunable, and switchable circularly polarized laser emission would have far reaching implications in optical communications or biophotonics. In this work, it is demonstrated the direct generation of circularly polarized (CP) laser emission in achiral and isotropic dye laser systems without the use of extracavity polarizing elements, and without resorting to chiral dyes, chiral liquid crystal matrices, or interferometric methods. The origin of this ellipticity arises from the dynamic birefringence induced by the strong and polarized laser pumping and the subsequent orientation anisotropy of the excited molecular dipoles. A complete polarimetric characterization of the polarization state of conventional dye laser oscillators as a function of different experimental parameters is performed and it is shown that the generated light always possesses a certain level of circularity that changes in a distinctive way with pump energy and polarization. These results demonstrate that it is possible to generate and modulate CP laser light from efficient and photostable conventional laser dyes.Peer Reviewe

Effect of chromophore-chromophore electrostatic interactions in the NLO response of functionalized organic-inorganic sol-gel materials

In the last years, important non-linear optical results on sol-gel and polymeric materials have been reported, with values comparable to those found in crystals. These new materials contain push-pull chromophores either incorporated as guest in a high Tg polymeric matrix (doped polymers) or grafted onto the polymeric matrix. These systems present several advantages; however they require significant improvement at the molecular level - by designing optimized chromophores with very large molecular figure of merit, specific to each application targeted. Besides, it was recently stated in polymers that the chromophore-chromophore electrostatic interactions, which are dependent of chromophore concentration, have a strong effect into their non-linear optical properties. This has not been explored at all in sol-gel systems. In this work, the sol-gel route was used to prepare hybrid organic-inorganic thin films with different NLO chromophores grafted into the skeleton matrix. Combining a molecular engineering strategy for getting a larger molecular figure of merit and by controlling the intermolecular dipole-dipole interactions through both: the tuning of the push-pull chromophore concentration and the control of TEOS (Tetraethoxysilane) concentration, we have obtained a r33 coefficient around 15 pm/V at 633 nm for the classical DR1 azo-chromophore and a r33 around 50 pm/V at 831 nm for a new optimized chromophore structure.Comment: 10 pages, 11 figures, 1 tabl

Bichromatic laser emission from dipyrromethene dyes incorporated into solid polymeric media

9 pages, 9 figures.Bichromatic laser emission from dipyrromethene-based solid-state dye lasers is reported. The dependence of this dual emission on different factors and its origin and causes are discussed in the light of different models proposed in the literature. Our experimental results indicate that the long-wavelength emission can be explained in terms of reabsorption/reemission effects and inhomogeneous broadening of the S0-S1 transition. The short-wavelength emission corresponds to the usual S0-S1 transition and dominates at low dye concentration.This work was supported by Project Nos. MAT2004-04643-C03-01 and MAT2004-04643-C03-02 of the Spanish CICYT. One of the authors (M.Á.) thanks Ministerio de Ciencia y Tecnología (MCT) for a predoctoral grant. Another author (M.L.) thanks Comunidad Autónoma de Madrid for a postdoctoral grant and MCT for a Juan de la Cierva contract.Peer reviewe

8-PropargylaminoBODIPY: unprecedented blue-emitting pyrromethene dye. Synthesis, photophysics and laser properties

Highly emitting 8-propargylaminoBODIPY (8-PAB) 2 was prepared in 94% yield. Unlike any other BODIPY structure hitherto described in the literature, 2 displays efficient emission in the blue region of the visible spectrum with a fluorescence quantum yield up to 0.94 and high laser efficiency (35%) at 483 nm.Grants GTO-2007-C02-69094 (CONCyTEG) (Mexico), MAT2007-65778-C02-01 and -02 of the Spanish MICINN are gratefully acknowledged. V. Martin thanks CSIC for her JAE-postdoctoral contract.Peer reviewe

Laser performance of pyrromethene 567 dye in solid polymeric matrices with different cross-linking degrees

We report on the laser action of pyrromethene 567 ͑PM567͒ incorporated into copolymers of methyl methacrylate ͑MMA͒ with different methacrylic and acrylic cross-linking monomers: ethyleneglycol dimethacrylate, trimethylolpropane trimethacrylate, tetraethyleneglycol diacrylate, pentaerythritol triacrylate, and pentaerythritol tetraacrylate ͑PETRA͒. The vol/vol proportion of the different co-monomers in each copolymer formulation was systematically varied, and the effect of each composition on the lasing properties of PM567 was evaluated. The laser samples were transversely pumped at 534 nm with 5.5 mJ/pulse from a frequency doubled Q-switched Nd:KGW laser. Lasing efficiencies of up 26% and good stability with a drop of the initial laser output of 30% after 100 000 pump pulses at 5 Hz in P͑MMA:PETRA 95:5͒ were demonstrated

The artificial cave 14 in the necropolis of los Algarbes (Tarifa, Cádiz). Death and funerary ritual in the middle of the III millennium BCE

Este trabajo se centra en el estudio de la cueva artificial 14, perteneciente a la necrópolis prehistórica de Los Algarbes (Tarifa, Cádiz). Profundizaremos en la realidad de la muerte y el ritual funerario a través del registro arqueológico del continente (estructura funeraria) y de su contenido (ajuar funerario y registro antropológico). Además, realizaremos una contextualización histórica y paleoambiental tanto en la propia necrópolis como en el extremo S de la península ibérica a través de su datación absoluta.This article focuses on the study of the artificial cave 14, which belongs to the prehistoric necropolis of “Los Algarbes” (Tarifa, Cádiz). In this context, we will delve into the death and the funerary ritual through the archaeological record from both the continent (funeral structure) and its contents (grave goods and anthropological record). In addition, we will carry out a historical and palaeoenvironmental contextualization both in the own necropolis and in the Southern end of the Iberian Peninsula

Photophysical and laser emission studies of 8-polyphenylene-substituted BODIPY dyes in liquid solution and in solid polymeric matrices

In our search for efficient and photostable laser dyes, four new dyes with the basic structure of the commercial BODIPY laser dye PM567, with either an 8-diphenylene or an 8-p-triphenylene group, both substituted at the terminal polyphenylene position with an acetoxymethyl (dyes P2Ar1Ac and P3Ar1Ac, respectively) or a methacryloyloxymethyl group (dyes P2Ar1MA and P3Ar1MA, respectively), have been synthesized. The photophysical and lasing properties of the dyes have been studied both dissolved in liquid solvents (acetoxymethyl dyes) and incorporated into solid polymeric matrices, in the latter case as solutions (acetoxymethyl dyes) or as copolymers with methyl methacrylate (methacryloyloxymethyl dyes). In liquid solution, the photophysics of P2Ar1Ac and P3Ar1Ac is scarcely affected by the number (two or three) of p-phenylene units. Quantum mechanical calculations reveal that the p-phenylene units in these dyes are twisted ca. 37◦ each other, an that the first 8-p-phenylene group stands nearly perpendicular to the aromatic BODIPY plane, resulting in electronic decoupling of the two chromophores. P2Ar1Ac exhibits a somewhat lower photodegradation quantum yield under UV and visible irradiation, if compared with P3Ar1Ac or with PM567, likely because of its also lower rate constant for the reaction with in situ-generated singlet molecular oxygen. Both acetoxymethyl dyes emit laser radiation in solution in all the solvents tried, under transversal pumping at 532 nm. In ethyl acetate, with a dye concentration of 0.80 × 10−3 M, laser efficiencies as high as 80% have been observed. When the 8-polyphenylene dyes were incorporated into solid poly(methyl methacrylate) (PMMA) matrices, as solutions or as copolymers, the fluorescence emission increased with respect to that of the parent PM567 dye dissolved in the same matrix, and lasing efficiencies in the range 18–31% were obtained, with good photostability. The dye P2Ar1Ac dissolved in PMMA was found to exhibit the best overall laser behavior, with a good balance between efficiency and photostability.This work was supported by Project MAT2004-04643-C03-01 of the Spanish CICYT. M. Liras thanks Comunidad Aut´onoma de Madrid for a predoctoral scholarship and Ministerio de Educaci´on y Ciencia for a Juan de la Cierva contract.M. A´ lvarez thanks Ministerio de Educaci´on y Ciencia for a predoctoral scholarship. The 8-polyphenylene-substituted boron-dipyrromethene dyes described in this paper and their utilization in liquid and solidstate dye lasers are covered by Spanish PatentNo. P200701763 filed on 25 June 2007.Peer reviewe