Rhodamine 6G Laser Research Articles

Investigating The Effects of The Different Rhodamine 6G Laser Dye Volume Ratios on The Optical Properties of PMMA/PC Films

Rhodamine 6G – polymethylmethacrylate/polycarbonate (Rh6G–PMMA/PC) were prepared by a casting method at room temperature with diverse volume ratios of Rh6G dye solution (5, 10, 15, 20 and 25) ml. The as-prepared films were categorised via UV–Vis spectrophotometer, and the optical properties were investigated in the wavelength range of (200-800) nm. The absorption peaks for pure PMMA/PC film were affected by inserting Rh6G dye solution, the wavelength of absorption peak of pure PMMA/PC film is at 300 nm and 340 nm while there are different behaveior at different concentration of RG6 after mixing with PMMA/PC films; there are red shift for concentrations (10 and 25 ml) of RG6 after mixing with PMMA/PC films by appear another peaks at 530 nm and 535 nm respectively. In addition, there is a blue shift for concentrations (15 and 20 ml) of RG6 after mixing with PMMA/PC films, as evidenced by the appearance of new peaks at wavelength 265 nm. Furthermore, new peaks appeared and were absorbed while the energy band gap was influenced, with values ranging from 4.3 eV for pure PMMA/PC film to 4.18 eV for mixtures 10 and 25 ml concentration of Rh6G/ PMMA/PC belonging to the red shift to 4.9 eV and 4.85 eV for mixtures 15 and 20 ml concentration of Rh6G/ PMMA/PC belonging to the blue shift.

Quantized molecular intercalations of Rhodamine 6G laser dye onto polymethylmethacrylate host exciplex

Polymethylmethacrylate (PMMA) and Rhodamine 6G (R6G), were used to achieve an electronically excited R6G/PMMA complex of definite stoichiometry as an active laser exciplex, pumped by different laser sources. This paper is the first that is capable of interpretation of the interactions of the reactants to form the exciplex on the molecular level using DFT. The system was prepared by thermochemical polymerization, and structurally identified using FTIR, XRD and SEM in conjunction with DSC. In low-to moderate-loading of R6G, FTIR and XRD studies indicated a good interaction between PMMA and R6G to give poor-or semi-crystalline structures. Higher dye loadings were achieved for the synthesized exciplex; loading of PMMA with 0.25 Wt-% R6G decreased the glass transition temperature from 98.74 °C to 70.08 °C. However, increasing the loading with R6G to 5 Wt-% and 20 Wt-% increased the Tg values to 86.26 and 91.90 °C, respectively. MD simulations were conducted; the electronic mobility within the system was related to different quantum parameters, EHOMO, ELUMO, η, μ and ω were about -7.671 eV, -5.241 eV, 1.215 eV, -6.456 eV and 17.1522 eV, respectively. DFT calculations indicated that R6G/PMMA has a characteristic lasing stability, so that the lasing lifetimes about 8000 pulses and efficiencies about 21% were obtained.

Circular, Plane-Directional Radiation from the Edges of Light-Excited Layer of a Laser Dye Solution with the Regular Geometric Form

Homogeneous light excitation of the Rhodamine 6G laser dye alcohol solution layer of rectangular and circular geometric form by the second harmonic of Nd:YAG (532 nm) laser is realized. A circular, plane-directed radiation from the edges of the excited layer with a small, vertical, divergence was obtained. Was investigated experimentally the spectral and spatial characteristics of radiation. The investigated layer is a part of the dye solution that is in direct

Effect of pump-induced loss on the spectral dependence of Rhodamine 6G laser efficiency under microsecond coherent pumping

We examine the effect of the pump-induced loss in the gain medium of a Rhodamine 6G laser on the spectral dependence of the laser efficiency under microsecond coherent pumping. It is shown theoretically and experimentally that the pump-induced loss is mainly due to nonlinear refraction and thermo-optic inhomogeneities of the gain medium, which produce a negative thermal lens, whose defocusing effect reduces the laser efficiency. The induced absorption by excited-state singlet and triplet levels of dye molecules is shown to make no significant contribution to changes in laser efficiency. The pump-induced thermal loss at the peak absorption wavelength of Rhodamine 6G plays a more important role well above the threshold pump power density (γ ⩾ 5). We demonstrate that the maximum dye laser efficiency under microsecond coherent pumping can only be achieved at an optimal pump wavelength.

Impact of PS/PMMA Polymer Ratios with Nanocomposite Material on Optical and Morphological Properties

In this work, nanocomposite material consisting of titanium dioxide (TiO2) nanoparticles and rhodamine 6G (R6G) laser dye was doped with different ratios of polystyrene (PS) and polymethylmethacrylate (PMMA) polymer blends (i.e. 40% PS/60% PMMA and 50% PS/50% PMMA) using the casting method. The optical properties of the prepared samples were measured using UV-visible spectroscopy. These measurements include the calculations of the absorption (A%), absorption coefficient (α), energy gap (Eg), refractive index (n), extinction coefficient (K) and real and imaginary parts. These nanocomposite materials were investigated using a scanning electron microscope and photoluminescence (PL) spectra emission. The SEM results show that the optimum results were at 50% PS/50% PMMA/TiO2/R6G with all the dye being decorated in the process blend, while the TiO2 nanoparticle demonstrated that the pores were incomplete in some places and complete in others. The optical results show that there are red shifts in all absorption peaks caused by the increased PS ratio. The Eg decreased from 3.2 eV to 2.8 eV as the concentration of PS in the polymer matrix increased. The PL spectrum for the nanocomposites, with a different ratio of PS, shows that sharp peaks of PL emission occur at a wavelength of 570 nm and shift towards longer wavelengths with an increased PS%.

Physical Properties of Rhodamine 6G Laser Dye Combined in Polyvinyl Alcohol films as Heat Sensor

Rhodamine 6G- polyvinylalcohol (Rh6G/PVA) films were prepared via casting route at room temperature with different volume of Rh6G dye solution (5, 10, 15, 20, 25 and 30 ml). The optical properties of as-prepared films were characterized using UV–Vis spectrophotometer at a wavelength range of 200-800 nm. The absorption peak of the pure PVA film does not affect by adding the Rh6G dye solution while exhibited increase in intensity of the absorption spectrum. Furthermore, the absorption peak of Rhodamine 6G demonstrated red-shift about 10 nm. Energy band gap slightly affected by adding Rh6G dye solution. The amazing influence of heat treatment on the physical properties of Rh6G/PVA films appeared due to red-shift and decrease the energy band gap. The results exposed that the best sensitivity calculated at temperature 40 °C for as-grown Rh6G (15 ml)/PVA film around 35.74%.

Embedded Spherical Microlasers for In Vivo Diagnostic Biomechanical Performances

Abstract In this article, we propose to use spherical microlasers that can be attached to the surface of bones for in vivo strain monitoring applications. The sensing element is made of mixing polymers, namely, PEGDA-700 (Sigma Aldrich, St. Louis, MO) and Thiocure TMPMP (Evan Chemetics, Teaneck, NJ) at 4:1 ratio in volume doped with rhodamine 6G (Sigma Aldrich, St. Louis, MO) laser dye. Solid-state microlasers are fabricated by curing droplets from the liquid mixture using ultraviolet (UV) light. The sensing principle relies on morphology-dependent resonances; any changes in the strain of the bone causes a shift of the optical resonances, which can be monitored. The specimen is made of a simulated cortical bone fabricated with photopolymer resin via an additive manufacturing process. The light path within the resonator is found to be about perpendicular to the normal stress' direction caused by a bending moment. Therefore, the sensor measures the strain due to bending indirectly using the Poisson effect. Two experiments are conducted: 1) negative bone deflection (called loading) and 2) positive bone deflection (called unloading) for a strain range from 0 to 2.35 × 10−3 m/m. Sensitivity values are ∼19.489 and 19.660 nm/ε for loading and unloading experiments, respectively (percentage difference is less than 1%). In addition, the resolution of the sensor is 1 × 10−3 ε (m/m) and the maximum range is 11.58 × 10−3 ε (m/m). The quality factor of the microlaser is maintaining about constant (order of magnitude 104) during the experiments. This sensor can be used when bone location accessibility is problematic.

Enhancement of Amplified Spontaneous Emission and Laser Performance of Rhodamine 6G/Cellulose Acetate DFB and DBR Waveguide Devices: A Role of Thermally Annealed P(VDF-TrFE) Intermediate Layer

Inserting a crystalline P(VDF-TrFE) intermediate layer under rhodamine 6G (R6G) laser active waveguide layer preserved the emissive R6G molecules in the matrix, which increases the intensity of flu...

Solid State Optical Microlasers Fabrication via Microfluidic Channels

In this paper, we propose the use of a microfluidic channel with flow focusing technique to fabricate solid state polymeric microlasers to precisely control sizes for mass production. Microlasers are made from a solution of UV curable polymer, namely polyethylene glycol diacrylate (PEGDA) with a molecular weight of 700 and rhodamine 6G laser dye at two different volumetric ratios (polymer to dye) of 4:1 and 2:1, respectively, which are used as the dispersed phase. A reservoir filled with liquid polydimethylsiloxane (PDMS) was used to cure the microlasers via UV lamp. A microchannel made of (PDMS) and size of 200 µm was used in this paper; mineral oil was selected as the continuous phase. Two experiments are conducted by fixing the pressure flow for the dispersed phase to 188 mbar and 479.9 mbar, respectively. In both experiments, the pressure of the continuous phase (mineral oil) was varied between 1666.9 mbar and 1996.9 mbar. The measurement of the fabricated microlasers’ size was performed with the aid of the MATLAB Image Processing Toolbox by using photographs taken with a CMOS camera. The tunability of the highest size, ranging from 109 µm to 72 µm, was found for the PEGDA to dye ratio of 2:1 (188 mbar) and average standard deviation of 1.49 µm, while no tunability was found for the 4:1 ratio (188 mbar). The tunability of the microlaser’s size, ranging from 139 µm to 130 µm and an average standard deviation value of 1.47 µm, was found for the 4:1 ratio (479.9 mbar). The fabricated microlasers presented a quality factor Q of the order 104, which is suitable for sensing applications. This technique can be used to control the size of the fabrication of a high number of solid state microlaser based UV polymers mixed with laser dyes.

High-Performance All-Organic DFB and DBR Waveguide Laser with Various Grating Height Fabricated by a Two-Photon Absorption DLW Method

Organic solid-state lasers (OSSLs) with distributed feedback (DFB) structures or distributed Bragg reflectors (DBRs) are promising for potential application in bio-sensing and hazardous materials detection. Here, the laser performances of the all-organic DFB waveguide lasers with various grating heights ranging from 0.4 to 4.7 μm were investigated. The grating structures used as the lasing cavity were fabricated using a two-photon absorption (TPA) direct laser writing (DLW) method with an SU-8 negative photoresist. The laser active layer consisted of a rhodamine 6G (R6G) laser dye and a cellulose acetate (CA) matrix. The R6G/CA solution was spin-coated onto the quartz substrate with the cavity (grating) structures to fabricate the DFB waveguide laser devices. The diffraction order of lasing ranged from m = 4 to 7. As the grating height was increased to 1.9 μm, the slope efficiency increased for all diffraction orders and the threshold decreases for each diffraction order. The dependence of the cavity (grating) length on the laser performances was investigated. The slope efficiency increased as the cavity length increased to 300 μm. The effect of the cavity (grating) position on the slope efficiency and the threshold position of the cavity (grating) was also studied. A maximum slope efficiency of 10.2% was achieved for the DFB waveguide laser device with a cavity (grating) length of 300 μm, a cavity position at 6 mm from the emission edge of the waveguide, and an aspect ratio ≈3 between the grating height of 1.74 μm and the grating width of 0.6 μm for the diffraction order m = 6 for lasing.

Random lasing action from electrospun nanofibers doped with laser dyes

We fabricated polyvinyl alcohol (PVA) nanofibers doped with Rhodamine 6G laser dyes via an electrospinning technique, which were then excited by a pulsed laser for laser emission. The laser was observed at a low threshold of several µJ and the intensity increased with the dye concentration. A single peak with a full width at half maximum (FWHM) of 4 nm was detected for a fiber of 300 nm diameter and multi-peaks with an FWHM of 2 nm were recorded as the diameter was increased to 800 nm. However, the multi-peaks tended to saturate to one laser peak with an intensive incident laser. The lasing mode was closely related to the diameters of the PVA fibers. Simulating results indicated that the single and multiple modes were closely related to the pump wavelength. The nanofiber as a network forming a random laser is expected to be used as a waveguide in communications and the multi-modes have potential application in cryptology.

Low threshold random lasing actions in natural biological membranes

We report random lasing actions stemming from natural biological membranes doped with Rhodamine 6G (Rh6G) laser dye which were then stimulated by a pulsed laser. The membranes have concave–convex structures and are expected to form resonators for weak light scatterings. The laser emission varies with the type of membrane and is also closely related to the dye concentration and pump energy. The threshold for the laser generation obviously rises when the concentration of doped laser dye is increased. The simulation results show lasing distributions are localized, indicating that the laser modes are very sensitive to the indicant angles of pump light.

Random laser action from a natural flexible biomembrane-based device

Incoherent random lasing action in flexible eggshell membranes infiltrated with rhodamine 6G laser dyes is demonstrated. Laser radiation is achieved by exciting samples with 1-ns pulses at 526 nm. A threshold of 58 μJ/pulse is measured for the samples. The minimum threshold decreases to 35 μJ/pulse after the sample is coated with gold nanoparticles using a magnetron sputtering technique. The peaks of emission spectra are observed to redshift from 576 to 596 nm as dye concentration rises from 0.03 to 0.6 wt%. A linewidth of approximately 5 nm is obtained for most samples. This study is expected to offer a new way to induce lasing emission using biological microfibrils, and enriches basic knowledge of biophotonics.

Effect of Pore Size and Film Thickness on Gold-Coated Nanoporous Anodic Aluminum Oxide Substrates for Surface-Enhanced Raman Scattering Sensor.

A sensitive surface enhanced Raman scattering chemical sensor is demonstrated by using inexpensive gold-coated nanoporous anodic aluminum oxide substrates. To optimize the performance of the substrates for sensing by the Surface-enhanced Raman scattering (SERS) technique, the size of the nanopores is varied from 18 nm to 150 nm and the gold film thickness is varied from 30 nm to 120 nm. The sensitivity of gold-coated nanoporous surface enhanced Raman scattering sensor is characterized by detecting low concentrations of Rhodamine 6G laser dye molecules. The morphology of the SERS substrates is characterized by atomic force microscopy. Optical properties of the nanoporous SERS substrates including transmittance, reflectance, and absorbance are also investigated. Relative signal enhancement is plotted for a range of substrate parameters and a detection limit of 10−6 M is established.

The development of polymer laser-active media with improved performances

The influence of modification of organic glass by additives new derivatives of thiazole and thiourea on the spectral-fluorescent and lasing characteristics of the Rhodamine 6G laser dye has been investigated. For the sample modified by additive - N-(4-carbomethoxy- 5-phenyl-thiazol-2-yl)-N'-phenylthiourea taken in amounts of 0.01 mol% the maximum rise of the absorption and fluorescence intensity to compare with the unmodified sample 1.3 and 2.3 times, respectively, was detected. The 8.3 times more lasing energy, and the 7.3 times higher laser photostability has been achieved.

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.

Random Laser of R6G Dye and TiO<sub>2</sub> Nanoparticals Doped in PMMA Polymer

The random laser (RL) based on organic Rhodamine 6G (R6G) laser- dye and Titanium dioxide (TiO2) suspended nanoparticles have been prepared with polymethylmethacrylate (PMMA) as a host. Both liquid and spray-coated homogeneous film samples of 22.4 µm - 30.1 µm thickness range were use. Optimum concentrations have been determined depending on the normal fluorescence spectra which give evidence that the laser dye provides amplification and TiO2 nanoparticles as scatter center. At the optimum concentrations, results of the random laser (RL) under second harmonic Nd: YAG laser ex-citation show that the values of bandwidth at full width half-maximum (FWHM) and the threshold energy are about 9 nm and 15 mJ respectively, which represent the minimum value for the liquid samples in the current research. Correspondly, these values become 14 nm and 15 mJ for film sample. The broadening that can be attributed to the concentration quenching of a laser dye at high concentration levels has been observed.

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.

Sol–gel prepared AlPO 4 with incorporating Rhodamine 6G

Rhodamine 6G (RH6G) laser dye-doped AlPO 4 xerogel and glass were prepared via a simple sol–gel route by one-step process and two-step process, respectively. The aggregating behavior of dyes in xerogel and glass was studied by excitation and emission spectra. The results indicated the dye aggregates become significantly weak in AlPO 4 glass than in xerogel, which might be attributed to the enhanced interactions between dye and AlPO 4 network as well as the nano-scale separation of dye by the mesoporous structure of AlPO 4 glass. The 27Al MAS NMR of AlPO 4 glass confirms the interaction of RH6G with AlPO 4 glass network. Incorporation of RH6G into AlPO 4 glass converts Al(4) to Al(6) units, resulting in the increase of Al(6) concentration with the doped RH6G concentration.

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.