Rhodamine 6G Dye Laser Research Articles

Spectral fluctuations of a high repetition rate dye laser through a flowing gain medium

In this paper, wavelength and bandwidth fluctuations of a Rhodamine 6G dye laser, transversely pumped by CVL, through a flowing gain medium are investigated. The gain medium mass flow rates were varied in the range 1–6 l min−1 (LPM). Analysis of the wavelength and bandwidth fluctuations of the dye laser was carried out using a high resolution Fabry–Perot etalon based setup and composite images generated from spectral profiles. The wavelength varied within 0.0290, 0.0240, 0.0200, 0.0120, 0.0110 and 0.0200 nm while the bandwidth was within 1.340, 0.912, 0.679, 0.301, 0.296 and 0.509 GHz at flow rates of 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0 LPM, respectively. The minimum fluctuations, which depend on the experimental conditions, were observed at ∼5 LPM. Spectral fluctuations at particular flow rates depend mainly on the microscopic fluctuations in the temperature and flow velocity inside the boundary layers.

Surface roughness induced random lasing in bio-polymeric dye doped film

Here we report on the surface roughness induced random lasing phenomenon observed in thin film of biophotonic matrix – an modified deoxyribonucleic acid with cationic surfactant cetyltrimethylammonium chloride, doped with Rhodamine 6G laser dye. The random lasing was achieved using doubled in frequency Nd:YAG nanosecond pulse laser as a source of excitation. The experiments were carried out for different lengths of excitation areas resulting in lasing fluence threshold reduction from 16.6mJ/cm2 down to 33μJ/cm2. Using Fast Fourier Transformation analysis of random lasing spectra an average resonator length was estimated to amount 37μm.

Fingerprint visualization enhancement by deposition of columnar thin films and fluorescent dye treatment

Enhanced visualization of latent fingerprints on two non-porous surfaces, smooth glass slides and highly reflecting rough aluminum sheets, is obtained by depositing columnar thin films (CTFs) of calcium fluoride (CaF2) and silica (SiO2) by physical vapor deposition at large oblique angles. Due to the vapor flux getting shadowed by the physical residues in the fingerprints, the CTFs are deposited only on the upraised ridges, resulting in highly enhancing the visibility of the fingerprint. The visualization of these fingerprints with deposited CTFs is further enhanced by subsequently treating them with a fluorescent dye and fluorescence imaging. A specific amino-acid reagent (1,2-indanedione) and non-specific laser dye (Rhodamine 6G), both allowed enhanced visualization of the CTFs grown on the fingerprints, due to the localization and entrenchment of the dye within the CTF regions.

Optofluidic microring dye laser embedded in polydimenthylsiloxane with reduced threshold

We demonstrate an integrated optofluidic microring dye laser with a relatively low threshold on a polydimenthylsiloxane (PDMS) chip. The chip was fabricated through conventional soft lithography. It consists of a liquid waveguide with microring structure providing the feedback. A reduced threshold is realized due to the unique design of the bus waveguide across the center of the microring structure, which results in a great reduction in the cavity losses. Laser dye rhodamine 6G (R6G) dissolved in benzyl alcohol was injected into the microfluidic channel as the gain medium. When the dye laser was pumped with a pulsed laser at 532 nm, the dye laser oscillation was achieved with a threshold of only 4–5 μJ mm−2. The convenience in fabrication and operation makes the optofluidic microring dye laser a promising underlying photonic component in the integrated optofluidic systems.

Low threshold amplified spontaneous emission from dye-doped DNA biopolymer

In this study, we investigate the amplified spontaneous emission (ASE) properties and conduct a comparative study for two kinds of dye-doped deoxyribonucleic acid (DNA) biopolymers. The system consists of optical films made of DNA modified by two types of surfactants and doped with a common laser dye rhodamine 6G (Rh6G). The ASE properties of the optical films were characterized by a pulsed Nd:YAG laser. The results show that low threshold of DNA biopolymer can be achieved by the employment of suitable surfactant in the system, resulting from an efficient energy transfer process. Coupled with the fluorescence enhancement exhibited in DNA, this effect can further advance biopolymers toward highly efficient media for lasing applications and organic solid-state lasers.

Fluorescence intensification of Rhodamine 6G in Zirconia-Glymo glasses

Laser dye Rhodamine 6G incorporated into Zirconia-Glymo (Glymo-3-Glycidoxypropyltrimethoxysilane) glasses obtained by sol–gel method shows increased luminescence in presence of silver nanoparticles (NPs). The mechanism of the increase was studied by continuous and dynamical fluorescence. The intensity enhancement of fluorescence by 225% was obtained in glasses co-doped with silver NPs. The experimental results allow concluding that the increase of fluorescence is mainly due to the interaction of the dye molecules with the scattering of silver plasmons.

Simultaneous measurements of absorption spectrum and refractive index in a microfluidic system

The characterization of dyes in various solvents requires determination of the absorption spectrum of the dye as well as the refractive index of the solvent. Typically, the refractive index of the solvent and the absorption spectrum of the solute are measured using separate experimental setups where significant liquid volumes are required. In this work the first optical measurement system that is able to do simultaneous measurements of the refractive index of the solvent and the spectral properties of the solute in a microscopic volume is presented. The laser dye Rhodamine 6G in glycerol is investigated, and the refractive index of the solution is monitored using the interference pattern of the light scattered off the channel, while its spectral properties is found by monitoring reflected light from the channel.

Distributed feedback leaky laser emission from dye doped gel-glass dispersed liquid crystal thin film patterned by soft lithography

Gel-glass dispersed liquid crystal (GDLC) thin films doped with organic laser dye Rhodamine 6G (R6G) were prepared via a sol–gel procedure of tetraethyl orthosilicate (TEOS) and ethyl triethoxisilane (ETES). As characterized by scanning electronic microscope (SEM), surface-relief structures were successfully patterned on lower refractive index GDLC thin films by soft lithographic technology, which support distributed feedback (DFB) laser emission based on leaky mode propagation. The performance of the DFB laser emission was investigated and the spectral narrowing of the emitted radiation and the fine structure pattern were found to be controlled by the doping concentration of liquid crystal (LC) 4-cyano-4′-pentylbiphenyl (5CB). We also showed the synchronous excitation of a DFB lasing with random lasing mediated by light scattering inside the same GDLC leaky waveguide.

Adsorption of Cationic Laser Dye onto Polymer/Surfactant Complex Film

Fabrication of complex molecular films of organic materials is one of the most important issues in modern nanoscience and nanotechnology. Soft materials with flexible properties have been given much attention and can be obtained through bottom up processing from functional molecules, where self-assembly based on supramolecular chemistry and designed assembly have become crucial processes and technologies. In this work, we report the successful incorporation of cationic laser dye rhodamine 6G abbreviated as R6G into the pre-assembled polyelectrolyte/surfactant complex film onto quartz substrate by electrostatic adsorption technique. Poly(allylamine hydrochloride) (PAH) was used as polycation and sodium dodecyl sulphate (SDS) was used as anionic surfactant. UV-Vis absorption spectroscopic characterization reveals the formation of only H-type aggregates of R6G in their aqueous solution and both H- and J-type aggregates in PAH/SDS/R6G complex layer-by-layber films as well as the adsorption kinetics of R6G onto the complex films. The ratio of the absorbance intensity of two aggregated bands in PAH/SDS/R6G complex films is merely independent of the concentration range of the SDS solution used to fabricate PAH/SDS complex self-assembled films. Atomic force microscopy reveals the formation of R6G aggregates in PAH/SDS/R6G complex films.

Spectral properties of rhodamine 6G in smectite dispersions: Effect of the monovalent cations

Montmorillonite monoionic forms with alkali metal and NH4+-cations were prepared by ion exchange. The hydration properties and binding of the ions to montmorillonite surface and the swelling properties of the mineral specimens were analyzed. Whereas Na+- and Li+-ions were fully hydrated over a large range of conditions, large size K+, NH4+, and mainly Rb+ and Cs+ ions were apt to bind directly to the oxygen atoms on the mineral surface. The forms with large ions exhibited reduced hydration and swelling and the absence of macroscopic swelling of the respective aqueous colloids. The interaction of laser dye rhodamine 6G (R6G) in montmorillonite colloids was investigated by absorption and steady-state fluorescence spectroscopies. Significant effects of the properties of both the inorganic ions and swelling properties of colloidal dispersions on R6G molecular aggregation were observed. Large amounts of the molecular aggregates were formed in the colloids of Na+- and Li+-montmorillonites. The aggregates absorbed light at significantly lower wavelengths (∼460nm) with respect to the light absorption by monomers (535nm). Fluorescence spectroscopy provided a key evidence for the assignment of the type of the aggregates: The emission of the aggregates at relatively low energies proved these assemblies are rather a mixed H-/J-type than ideal H-aggregates. The presence of parent inorganic cations of larger size led to a significant lowering of the amount of the R6G aggregates in favor of the monomers. Investigations of the evolution of the dye aggregation with time indicated basic features of dye aggregation reaction: The size of parent inorganic ions did not affect the reaction mechanism, but rather limited the extent of the reaction. Probably the forms with large inorganic ions, such as Rb+ and Cs+, did not provide sufficient surface for the formation of the large size assemblies of the dye. This property can be explained in terms of strong association of the large alkali metal ions to clay mineral surface, as well as to reduced swelling in the colloidal systems of respective forms.

Fluorescent AlPO 4 gels and glasses doped with Rhodamine 6G: Preparation, structural and optical characterization

Fluorescent AlPO 4 xerogels doped with different amounts of Rhodamine 6G (Rh6G) laser dye were prepared by a one-step sol–gel process. In addition, mesoporous AlPO 4 glasses obtained from undoped gels were loaded with different amounts of Rh6G by wet impregnation. Optical excitation and emission spectra of both series of samples show significant dependences on Rh6G concentration, revealing the influence of dye molecular aggregation. At comparable dye concentrations the aggregation effects are found to be significantly stronger in the gels than in the mesoporous glasses. This effect might be attributed to stronger interactions between the dye molecules and the glass matrix, resulting in more efficient dye dispersion in the latter. The interaction of Rh6G with the glassy AlPO 4 network has been probed by 27Al and 31P solid-state NMR techniques. New five- and six-coordinated aluminum environments have been observed and characterized by advanced solid-state NMR techniques probing 27Al– 1H and 27Al– 31P internuclear dipole couplings. The fractional area of these new Al sites is correlated with the combined fractional area of two new Q (0) 3Al and Q (0) 2Al phosphate species observed in the 31P MAS NMR spectra. Based on this correlation as well as detailed composition dependent studies, we suggest that the new signals arise from the breakage of Al–O–P linkages associated with the insertion process.

On the Arrangements of R6G Molecules in Organophilic C12TMA/Lap Clay Films for Low Dye Loadings

Absorption and fluorescence spectroscopies with linearly polarized light are applied to characterize the adsorbed species of rhodamine 6G (R6G) laser dye in ordered organophilic laponite (Lap) clay films for low dye loadings. The organophilic character of the clay was controlled by the number of organic surfactant dodecyl-trimethylammonium (C12TMA) cations intercalated into the interlayer space of the clay. Experimental results suggest that for moderate to high surfactant contents (>70% of the total cation exchange capacity, CEC, of the clay) the accessibility of the interlayer space for R6G molecules is reduced. In these cases, the first stage in the adsorption of R6G molecules is at the external surface, where dye molecules can self-associate even for very low dye loading (around 0.1%CEC), probably for the limitation of the external surface area. The presence of a nonfluorescent H-type aggregate with a short-displaced coplanar structure and a fluorescent oblique head-to-tail J aggregate is reported. The inclined structure of this J aggregate is stabilized by the surfactant molecules at the external surface.

Selective mode excitation in dye-doped DNA polyvinyl alcohol thin film

A solid-state laser based on a dye-doped deoxyribonucleic acid (DNA) matrix is described. A thin solid film of DNA has been fabricated by treating with polyvinyl alcohol (PVA) and used as a host for the laser dye Rhodamine 6G. The edge emitted spectrum clearly indicated the existence of laser modes and amplified spontaneous emission. Lasing was obtained by pumping with a frequency-doubled Nd:YAG laser at 532 nm. For a pump energy of 10 mJ/pulse, an intense line with FWHM approximately 0.2 nm was observed at 566 nm due to selective mode excitation.

Effect of surfactant C12TMA molecules on the self-association of R6G dye in thin films of laponite clay

The effect of the surfactant dodecyltrimethyl ammonium (C12TMA) molecules on the aggregation of rhodamine 6G (R6G) laser dye intercalated in the interlayer space of clay laponite (Lap) thin films is studied by absorption and fluorescence spectroscopies. The presence of C12TMA molecules reduces in nearly one order of magnitude the tendency of the dye molecules to self-associate. Moreover, the organophilic environment created by the surfactant molecules promotes the formation of fluorescent J-type R6G aggregates with respect to those aggregates formed in pure Lap films with a hydrophilic ambience. Consequently, the fluorescence ability of dye/clay systems is improved by the presence of surfactant molecules, mainly in those samples with moderate/high dye loadings.

Plasma Process. Polym. 1/2009

Cover: Luminescent nanocomposites containing Rhodamine 6G laser dye molecules are deposited by remote microwave plasma polymerization. The picture shows micrometric patterns generated by plasma etching using a shadow mask. The nanometric thin films are also intensely absorbent. Further details can be found in the article by F. J. Aparicio, A. Borras, I. Blaszczyk‐Lezak, P. Gröning, A. Álvarez‐Herrero, M. Fernández‐Rodríguez, A. R. González‐Elipe, and A. Barranco* on page 17.

Luminescent and Optical Properties of Nanocomposite Thin Films Deposited by Remote Plasma Polymerization of Rhodamine 6G

AbstractMechanically stable and insoluble fluorescent thin films have been deposited by sublimating Rhodamine 6G laser dye in the downstream region of a low‐power microwave ECR plasma using an experimental set‐up designed to control the interaction of the dye molecule with the glow discharge. The use of reactive organosilane plasmas allows to control the dye distribution inside the matrix, leading to solid nanocomposite thin films containing non‐aggregated dye molecules. The suppression of aggregates is a key issue to avoid fluorescence quenching. The obtained nanocomposite films are interesting because of their strong absorption and high fluorescence emission. In addition, they can be patterned using in situ plasma treatments in order to produce optically functional devices.magnified image

Photophysics of Rhodamine 6G Laser Dye in Ordered Surfactant (C12TMA)/Clay (Laponite) Hybrid Films

With the aim of designing highly luminescent hybrid materials in ordered solid host systems, surfactant molecules are incorporated into the interlayer space of Laponite clay sheets which are parallel stacked in supported films. The posterior inclusion of the photoactive dye rhodamine 6G in low concentrations induces a macroscopic arrangement of fluorescent molecules in a nanostructure organophilic environment with an anisotropic photoresponse to the linearly polarized light.

Dynamics of Rhodamine 6G Sorption into a Porous Tri-block Copolymer Thin Film

The dynamics of sorption of the laser dye rhodamine 6G (R6G+) into a thin ion-exchange polymer film was measured by spectroscopic ellipsometry. The system under study consisted of a nanometer-sized polymer film in direct contact with a liquid phase. A thin film of a partially sulfonated tri-block copolymer preconcentrated the dye from dilute solutions (10-5 M) driven by ion-exchange to a film concentration of about 0.1 M. Spectroscopic ellipsometry was used to simultaneously measure the dynamics of the film physical (thickness) and optical changes (refractive index n(λ) and extinction coefficient k(λ)). The sorption is ultimately accompanied by dye aggregation in the film, which results in shifts and splitting of features in the monomer absorbance spectrum. The formation of nonluminescent aggregates was also confirmed by emission spectroscopy. Desorption of the dye from the film resulted in a reversal of film physical changes. Spectroscopic results were quantitatively accounted for by constructing an opti...

In situ synthesis of dye-doped stainless-steel-net-supported mesostructured silica film for solid-state laser material

Optically active stainless-steel-net-supported mesostructured SBA-15 films have been fabricated by a simple sol–gel synthesis. Laser dye rhodamine 6G is doped in situ in the films to produce solid state dye lasers. Characterization by optical microscopy and field-emission scanning electron microscopy reveals that the surface of the film is smooth and macroscopic homogeneous without any crack and the stainless steel net acts as a good framework of the film. Mesoscopic ordering of the film is demonstrated by a combination of small-angle X-ray diffraction analysis and transmission electron microscopy investigation. The spectroscopic properties of the solid-state laser materials are measured by the second harmonic of a Q-switched Nd:YAG laser at 532 nm. A distributed feedback laser (DFB laser) is revealed through the gain narrowing of the band over threshold energy of 30 μJ and the occurring of superlinear dependence. The grids of the stainless steel nets are regarded as laser resonant structures for feedback of light, and the aperture of the grids plays an important role on the films’ optical performance. Such dye-activated mesostructured materials have potential application for the fabrication of solid state dye lasers and microphotonic devices.

Wafer-scale fabrication of polymer distributed feedback lasers

The authors demonstrate wafer-scale, parallel process fabrication of distributed feedback (DFB) polymer dye lasers by two different nanoimprint techniques: By thermal nanoimprint lithography (TNIL) in polymethyl methacrylate and by combined nanoimprint and photolithography (CNP) in SU-8. In both techniques, a thin film of polymer, doped with rhodamine-6G laser dye, is spin coated onto a Borofloat glass buffer substrate and shaped into a planar waveguide slab with first order DFB surface corrugations forming the laser resonator. When optically pumped at 532nm, lasing is obtained in the wavelength range between 576 and 607nm, determined by the grating period. The results, where 13 laser devices are defined across a 10cm diameter wafer substrate, demonstrate the feasibility of NIL and CNP for parallel wafer-scale fabrication of advanced nanostructured active optical polymer components, with a yield above 95%.