Laser Dye Rhodamine Research Articles

The Radiation of the light excited layer of the alcohol solution of the dye Rhodamine 6G

Was investigated experimentally the spectral and spatial characteristics of the radiation of a light-excited layer of an alcohol solution of the laser dye Rhodamine 6G (R6G) of rectangular and round geometric shape. The investigated layer is a part of the dye solution that is in direct contact with the bottom of the optical cells, the rectangular and circular sections of which determine geometric shape of the layer. Excitation of the layer was performed perpendicular to this layer by the second harmonic of the Nd+: YAG laser (λ = 532 nm) from the side of the cell bottom. Sufficiently strong, spectrally narrow-band radiation with a circular uniform distribution of intensity around the cells, in the plane of the luminescent layer, with a small divergence in the perpendicular plane was observed. It turned out that within the concentrations of the dye in the solution from 0.12w% to 0.03w%, the following processes are observed: Planely directed uniform, in intensity, radiation around the cell in the plane of the luminescent layer with a small vertical divergence; An increase in the amplitude of radiation pulses with a decrease in the concentration of the dye in the solution from 0.12w% to 0.03w%; Shifting of the maximum of the emission spectrum to the short-wave region and significant narrowing of the radiation spectrum and decrease of the vertical divergence of radiation.

Characterization of a pulsed rhodamine/ethanol dye laser

We present here the implementation and characterization of a rhodamine dye laser pumped by a pulsed, high-power solid-state laser. The employed dye consisted of a solution of rhodamine 6G in ethanol at different concentrations. To maximize the laser efficiency the second harmonic of a pulsed Nd: YAG was used to collinearly pump the cavity. In particular, the effect of rhodamine concentration and pump energy on the laser emission were investigated. The laser emission obtained was found to have, on average, a width at half maximum (FWHM) of 12 nm. It was found, for example, that the wavelength of the output line varies linearly with the dye’s concentration. Under the employed experimental conditions, maximum efficiency of 12% is obtained with a concentration of 2.5×10−7 mol/l rhodamine in alcohol.

Concentration dependence of two-photon absorption in PMMA polymeric films doped with rhodamine laser dyes

We have studied poly(methyl methacrylate) (PMMA) films doped with rhodamine 6G and rhodamine B laser dyes as potential nonlinear material components for nanophotonics. For both dyes, the optimal concentrations, at which the emission excited via the two-photon-absorption (TPA) process is maximized, have been determined. Despite relatively large values of TPA cross sections obtained in this study, the characteristic pumping densities needed to observe pronounced nonlinear effects substantially exceed the laser damage threshold for Au or alternative plasmonic materials. This makes the studied laser dyes unsuitable for some of the intended nanophotonics applications.

Multichannel Smartphone Spectrometer Using Combined Diffraction Orders

A robust multichannel smartphone spectrometer exploiting multiorder diffraction imaging on a smartphone camera is reported. The instrument utilizes a thin film diffractive element generating multiple orders of diffracted light from a broadband visible source (white LED, λ = 400-700 nm). The smartphone's CMOS camera captures all the diffraction orders simultaneously, producing a 2-D image. Each of these diffraction orders can be utilized as a single optical channel for dedicated samples enabling simultaneous multiple sample analysis. The wavelength distribution along the diffraction direction produces a tunable spectral resolution of δλ ~1.6 to 3.0 nm/pixel over the bandwidth of Δλ = 300 nm. A customized app processes each diffraction image into spectra. 3-D printing is used to create the entire instrument prototype. As an initial demonstration, simultaneous absorption measurements of reference and sample cells using the first diffraction orders (m = +1 and -1) is shown. Absorption spectra for a laser dye (Rhodamine B) and a pH-responsive buffer (bromothymol blue) are measured. This offers a low cost (<; $30) portable instrument layout comparable to conventional double beam benchtop instruments in performance but more rugged for field use.

Synthesis and optical properties of 1-naphthol rhodamine for deep red laser dyes

In this study, we synthesized two asymmetric rhodamine laser dyes based on 1-naphthol (Dye-1 and Dye-2) and investigated their photophysical and laser performances. It was found that the fluorescence emission wavelengths of the two dyes are successfully extended to the deep red region. Compared with Dye-1, the esterification product Dye-2 displays a redshift of ∼8 nm in the maximum absorption wavelength (λabs) and fluorescence emission wavelength (λem). In aprotic solvents, both λabs and λem of Dye-2 red-shift with the increase of solvent polarity, while its fluorescence quantum yield always decreases with the increase of solvent polarity, no matter in protic solvents or aprotic solvents. The results of laser tests indicated that both Dye-1 and Dye-2 have wide laser tuning range and strong laser conversion efficiency in the red region. The laser conversion efficiency is closely relative to the dye concentration and linearly increases with the increase of pump laser energy.

Optical characterization of graphene-f-o-phenylenediamine and charge transfer interaction with organic dyes

Carbon based nanomaterials can effectively be doped to tailor their electronic and optical properties for various applications. In this work, we have synthesized and characterized the o-phenylenediamine doped graphene (G-f-OPD) to study the charge transfer with a standard laser dye rhodamine 6G (R6G). A comparison with pristine graphene shows that the static quenching efficiency of the graphene is 25 times higher than that of the G-f-OPD. Time-resolved measurements reveal the absence of dynamic quenching of the dye in presence of graphene and its nitrogen doped derivative. Nonlinear optical characterization of G-f-OPD has also been done in presence of R6G by degenerate four wave mixing (DFWM) technique. The measured values of third order optical nonlinearity (χ(3)) reveals the fact that the dominant contribution to the optical nonlinearity is due to its real part at the probe wavelength (532 nm). Furthermore, the nonlinear optical study by Z-Scan technique shows that G-f-OPD-R6G composite can be suitable for passive mode-locking applications.

Tunable Induced Circular Dichroism in Thin Organic Films

In this work, we study the induced optical activity (OA) of spin-coated molecular films made of a pristine optically inactive laser dye (Rhodamine 110) in the visible range. The OA is brought about by a “transparent” chiral modifier (1,1′-Bi-2-naphthol). For the first time, it was experimentally shown how two separate mechanisms yield induced circular dichroism (ICD) in such a film and how they are describable through a model. In one, ICD occurs via a direct interaction between dye and modifier molecules. In the other, ICD takes place in optical transitions of present dye aggregates. It is proposed that this is caused by a chiral bias through an enantiomeric excess in inherently chiral and optically active dye aggregates promoted by the chiral modifier in a sergeant-soldier manner. Further, the strength of ICD strongly depends on the ratio between the modifier and the dye as well as on the preparation conditions. The resulting high tunability of the OA paired with a straightforward film preparation opens ...

Fano Resonances and Photoluminescence in Self-Assembled High-Quality-Factor Microbottle Resonators

We demonstrate self-assembly of microbottle resonators (MBRs) that support high-quality-factor (high-Q) whispering gallery modes (WGMs). Polymethyl methacrylate (PMMA), a transparent organic polymer, has been used for the self-assembly. Active MBRs have been created by doping PMMA with laser dye rhodamine 6G. WGM-modulated photoluminescence has been observed from the active MBRs. The self-assembled passive MBRs show Q-factors of the order of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> . Fano- and electromagnetically induced transparency-type resonances have been observed in the transmission spectra.

Photo-induced intermolecular electron transfer-effect of acceptor molecular structures

Photo-induced electron transfer versus molecular structure of acceptors is investigated using ultrafast time-resolved transient grating spectroscopy. Typical laser dyes Rhodamine 101 (Rh101) and Rhodamine 6G (Rh6G) in electron donor solvent—aniline are adopted as the objects. The forward electron transfer time constant from aniline to the excited singlet state of two Rhodamine dyes and subsequent back electron transfer from two dyes to aniline are measured. The experimental results denote that Rh6G presents faster electron transfer rates with aniline in both forward electron transfer and back electron transfer processes. With chemical calculation and qualitative analysis, it is found that the flexible molecular geometry of Rh6G leads to stronger electron coupling with donor solvent and further gives rise to larger electron transfer rates.

Organic-inorganic hybrid microdisk laser with dye and silica mixed doping prepared by ink-jet printing method

We developed an ink-jet printing method for fabricating inorganic microdisks at room temperature, which is much lower than the melting point of solid-state inorganic oxide, and have fabricated an organic-inorganic hybrid microdisk laser. Silica was used as the inorganic disk material, and microdisk-shaped aggregates were formed by the ink-jet printing method using a solution in which nanosilica particles were dispersed in propylene glycol monomethylether (PGME) solvent. Then, a microdisk capable of laser oscillation was also prepared by preliminarily adding the laser dye rhodamine 6G to the ink to form a mixed organic material. The structural evaluation of the printed microdisk was first conducted using an optical microscope, a scanning electron microscope (SEM), and an atomic force microscope (AFM). The results of laser oscillation evaluation by optical excitation showed that the printed microdisk sufficiently functions as an optical resonator with a low optical loss. In these evaluations, excellent values such as a surface roughness of 5.83 nm from root mean square (R. M. S.) which is one forth smaller than the particle diameter, and a laser oscillation threshold of 4.76 µJ/mm2 at a wavelength of 601.4 nm were obtained. To the best of our knowledge, this is the first time that an inorganic microdisk has been fabricated at room temperature to realize an organic-inorganic hybrid microdisk laser.

Solvent effect on the femtosecond laser induced two-photon emission from Rhodamine 6G

Abstract Two-photon fluorescence microscopy attains widespread importance because of its applications in biological imaging. This technology provides a non-invasive study of biological specimens with better resolution in three dimensions with less photo damage. We report on two-photon excited emission from a widely used laser dye Rhodamine 6G in five different polar solvents using a mode-locked Ti: Sapphire pulsed laser. Solvent plays a major role in the photo physical properties of the lasing dye. There is a shift in the peak fluorescence wavelength as the concentration is varied. A solvent based shift in peak fluorescence wavelength is also observed. Maximum peak intensity is observed for the sample in the solvent ethanol. It was found that lifetime is varied depending on the nature of the solvent used.

One-pot synthesis of new acid photogenerators for Rhodamine laser dyes fluorescence activation

New aryl(hetaryl)pyrazolines fitted for fluorescence activation of Rhodamine laser dyes have been obtained via one-pot tandem Michael addition of two arylhydrazine molecules with 2-(4′-R-cinnamyliden)-2Н-furo[3,2-≿]coumarin-3-ones. These aryl(hetaryl)pyrazolines do not undergo tautomeric transformations both in organic solvents and in polymer films and behave themselves as effective acid photogenerators of Rhodamine dyes fluorescence activation. New aryl(hetaryl)pyrazolines can be used in the fabrication of two-photon volumetric optical memory materials.

Two Dimensional Host-Guest Metal-Organic Framework Sensor with High Selectivity and Sensitivity to Picric Acid.

A dye-sensitized metal-organic framework, TMU-5S, was synthesized based on introducing the laser dye Rhodamine B into the porous framework TMU-5. TMU-5S was investigated as a ratiometric fluorescent sensor for the detection of explosive nitro aromatic compounds and showed four times greater selectivity to picric acid than any state-of-the-art luminescent-based sensor. Moreover, it can selectively discriminate picric acid concentrations in the presence of other nitro aromatics and volatile organic compounds. Our findings indicate that using this sensor in two dimensions leads to a greatly reduced environmental interference response and thus creates exceptional sensitivity toward explosive molecules with a fast response.

Effect of nano-clay platelet on fluorescence resonance energy transfer

This communication reports the phenomenon of fluorescence resonance energy transfer observed in between the binary solution of two laser dyes acriflavine (donor) and rhodamine B (acceptor), with and without nano-clay (laponite). It was observed that presence of clay particles increases the energy transfer efficiency. The effect of acceptor concentration on the total energy transfer efficiency has been studied to quantify the energy transfer, which may be used for photon emission and enhancement in lasing efficiency.

Multi step FRET among three laser dyes Pyrene, Acriflavine and Rhodamine B

Fluorescence Resonance Energy Transfer (FRET) system using three dyes has been demonstrated. It has been observed that multi step energy transfer occurred from Pyrene to Rhodamine B via Acriflavine. Here Acriflavine acts as an antenna to receive energy from Pyrene and transfer the same to Rhodamine B. This multi step FRET system is advantageous compared to the conventional FRET as this can be used to study molecular level interaction beyond conventional FRET distance (1–10nm) as well as studying multi-branched macromolecules. The introduction of clay enhances the FRET efficiencies among the dye pair, which is an advantage to make the multi step system more useful. Similar approach can be used for increasing FRET efficiencies by using other dyes.

Fluorescence quenching of rhodamine 6G by 1,3,5-Trinitroperhydro-1,3,5- triazine entrapped in porous sol–gel silica

Fluorescence quenching of laser dye rhodamine 6G by codoping 1,3,5-Trinitroperhydro-1,3,5-triazine (RDX) in porous sol–gel silica is reported. It was found that the fluorescence intensity of rhodamine 6G decreases with increase in the concentration of RDX. Both the samples, predoped cylindrical shaped and postdoped thick film on glass substrate with RDX show the similar fluorescence quenching behavior. Emission spectra show slight red shifting with the increase in RDX concentration. An electron-transfer donor–acceptor mechanism is proposed for the observed fluorescence quenching. On the basis of these results, candidature of dye doped porous sol–gel silica as a sensor for explosive detection seems to be promising.

Development of a sensor to study the DNA conformation using molecular logic gates

This communication reports our investigations on the Fluorescence Resonance Energy Transfer (FRET) between two laser dyes Acriflavine and Rhodamine B in absence and presence of DNA at different pH. It has been observed that energy transfer efficiency is largely affected by the presence of DNA as well as the pH of the system. It is well known that with increase in pH, DNA conformation changes from double stranded to single stranded (denaturation) and finally form random coil. Based on our experimental results two different types of molecular logic gates namely, XOR and OR logic have been demonstrated which can be used to have an idea about DNA conformation in solution.

Aryl(hetaryl)pyrazolines as new photoacid generators for optical information recording

Abstract Photodehydrogenation of aryl(hetaryl)pyrazolines in the presence of organohalogen compounds has been used for fluorescence activation of Rhodamine laser dyes both in organic solvents and in polymer films. The ability of aryl(hetaryl)pyrazolines as photoacids to generate a highly fluorescent Rhodamine dye can be used for optical information recording.

Two-threshold silver nanowire-based random laser with different dye concentrations

The feedback mechanisms of silver nanowire-based random lasers with different concentrations of laser dye rhodamine 6 G pumped by a nanosecond pulsed laser were demonstrated. It was shown that dye concentration greatly impacts on the optical amplification mechanism. At lower or higher dye concentrations, random lasers have a single threshold. At a proper concentration, the system shows transition from incoherent emission to coherent lasing and has two thresholds corresponding to incoherent feedback and coherent feedback, respectively. The corresponding physical mechanism was displayed. Also, the processes of fluorescence, incoherent feedback and coherent feedback were distinguished by the emission spectra in the time domain. The results will supply some guidance to clear the working mechanism of random lasers.

Spectroscopy and laser characterization of synthesized supramolecular host cucurbit[7]uril using aqueous Rhodamine B dye

Recent demonstration in augmenting the efficiency of aqueous Rhodamine dye lasers using cucurbit[7]uril (CB[7]), a deaggregating and photostabilizing host, has drawn interest in the synthesis and characterization of spectroscopic grade CB[7] in larger quantities. Synthesis of cucurbituril group of macrocycles always leads to the formation of various homologues of CB[n]s (n=5–7) with CB[7] as the minor product. The literature procedure has been optimized to get pure CB[7] in 12–14% yield by fractional crystallization and the purity was checked by NMR, MS and spectrophotometric titration. Laser performances of the synthesized and commercial CB[7] sample as an additive were evaluated using Nd-YAG (532 nm) pumped Rhodamine B aqueous dye lasers and comparable results were obtained.