Rhodamine 6G Dye Laser Research Articles

A non-mixing technique for enhancement of the tuning range of Rhodamine 6G using Rhodamine B

An optical scheme for extension of spectral tuning range of Rhodamine 6G by Rhodamine B is reported. The dye solutions are kept separately in a specially designed coupled resonator. The tuning range of Rhodamine 6G dye laser is extended from 564–609 to 564– 645 nm .

Studies on the effect of organic additives on the monolithicity and optical properties of the rhodamine 6G doped silica xerogels

Rhodamine 6G (R6G) laser dye doped silica xerogels were prepared by sol–gel processing using tetraethylorthosilicate [TEOS, Si(OC2H5)4] precursor, citric acid (CTA) catalyst and ethanolic R6G in the presence of various organic additives such as formamide (FA), N′methylformamide (N′MF), dimethylformamide (DMF), acetamide (AA), glycerol (GLY), oxalicacid (OXA), ethyleneglycol (EG) and diethyleneglycol (DEG). The organic additive/TEOS molar ratio was varied from 0.001 to 0.1 by keeping the TEOS/EtOH/H2O/CTA/R6G molar ratio constant at 1:5:7:1.2×10−3:9.2×10−6. It was found from the spectral studies of the additive modified R6G doped silica xerogels that the absorption maxima at 530 nm and emission maxima at 565 nm were increased with the addition of organic additive and with the increase of the additive/TEOS molar ratio. The transparency of the R6G doped silica xerogels was increased with the increase of additive/TEOS molar ratio from 0.001 to 0.1 with OXA, DEG and EG and in the case of DMF, N′MF, FA, AA and GLY, the transparency of the samples increased up to 0.014 of additive/TEOS molar ratio and then decreased for >0.014 of additive/TEOS molar ratio. Monolithic samples were obtained with all the organic additives. The percentage volume shrinkage of the samples was less EG and DEG and more with OXA additives.

A micro-cavity fluidic dye laser

We have successfully fabricated and characterized a micro-cavity fluidic dye laser with metallic mirrors, which can be integrated with other microfluidic systems without adding further process steps. A laser dye solution is pumped through a microfluidic channel containing the laser cavity. The microfluidic channel structure, which is formed in SU-8 photoresist, is sandwiched between Pyrex glass wafers, bonded together at low temperature by means of SU-8. The laser was characterized using Rhodamine 6G laser dye dissolved in ethanol as the active medium, and optically pumped by a frequency doubled Nd:YAG laser. The dye solution was optimized, and lasing was observed at a wavelength of 570 nm with a full width half maximum linewidth of 5.7 nm and the optical pumping power density threshold for lasing was 34 mW cm−2.

Efficient photon-to-electron conversion with rhodamine 6G-sensitized nanocrystalline n-ZnO thin film electrodes in acetonitrile solution

This work encompasses a study of the photosensitizing action of the commercially available laser dye rhodamine 6G (Rh 6G) on nanocrystalline n-ZnO thin film electrodes prepared by sol–gel technique. This dye, having strong absorption in the visible range with a pronounced absorption peak at 525 nm, was found to convert into electrical energy the visible light in the range of 450–560 nm. The electron injection by photo-excited dye molecules into the conduction band of ZnO was evidenced by the matching of the action spectrum of dye-capped ZnO electrode with the absorption spectrum of the dye in solution. The maximum incident photon-to-current conversion efficiency (IPCE) of Rh 6G-sensitized ZnO based cell was found to be 2.3% at 520 nm under short-circuit condition, which is nearly 1.5 times the IPCE value reported for Rh 6G-sensitized SnO2 based cell. Dependence of the photocurrent on light intensity and the stability of the photocurrent obtainable from the Rh 6G-sensitized ZnO based photoelectrochemical cell on its prolong operation were also determined. On irradiation of the semiconductor electrode with monochromatic light (λ=520 nm), the power conversion efficiency (η) of the (ZnO electrode/ Rh 6G—containing electrolyte/carbon electrode) cell was found to be 0.2% with fill factor value of 0.44. Open-circuit photovoltage up to ∼500 mV could be obtained with this cell under visible (λ>420 nm) and white lights illumination.

Heavy-water-based solutions of rhodamine dyes: photophysical properties and laser operation

Photophysical properties of heavy-water-based rhodamine dye solutions have been investigated, with a view to assess the suitability of heavy water as a solvent for high-power, high-repetition-rate dye lasers and amplifiers. We have measured the quantum yield of fluorescence of the commonly used dyes rhodamine-6G, rhodamine-B and kiton-red, dissolved in heavy water, ethanol and normal water. The performance of a heavy-water-based pulsed rhodamine-6G dye laser has been investigated in broadband, as well as in narrowband wavelength-tunable resonator configurations, yielding laser efficiencies comparable to those achieved with ethanolic solutions of the same dye. We have also studied the thermo-optic properties of normal and heavy water, using the Z-scan technique. Finally, photodegradation rates for laser dyes have been compared in heavy water, normal water and ethanol. Our results establish heavy water as a solvent superior to both ethanol and normal water, on account of the lower thermo-optic effects and the higher photostability of rhodamine dyes when dissolved in heavy water.

Fluorescence background suppression in Raman spectroscopy using combined Kerr gated and shifted excitation Raman difference techniques

AbstractAn exceptionally high level of fluorescence rejection from resonance Raman spectra was achieved using a combination of two techniques, namely Kerr gated temporal rejection with shifted excitation Raman difference spectroscopy. The method was able to recover the resonance Raman spectrum from the intense fluorescence background with a signal‐to‐noise ratio at least 10 times higher than that achievable with either of the two approaches used individually. To demonstrate the effectiveness of the technique we obtained the resonance Raman spectrum of the laser dye rhodamine 6G (1 × 10−3 mol dm−3) in methanol by excitation at 532 nm and measuring under the maximum of fluorescence emission at 560–590 nm. The method reached the photon shot noise limit of the residual fluorescence providing a detection limit for Raman spectra 106 times lower than the original fluorescence intensity in an accumulation time of 800 s. A unique feature of the experiment was the way in which the optical parametric amplifier light source was configured to alternate automatically between the two excitation wavelengths using an optogalvanic mirror arrangement. The ultra‐high sensitivity of the combined approach holds great promise for selective probing of complex biological systems using resonance Raman spectroscopy. Copyright © 2002 John Wiley & Sons, Ltd.

Dimer-to-Monomer Transformation of Rhodamine 6G in Aqueous PEO−PPO−PEO Block Copolymer Solutions

To construct a viable dye-based microlaser, it is necessary to achieve very high dye concentrations in a solid matrix. Increased aqueous solubility of the laser dye Rhodamine 6G has been demonstrated in liquid and gel phases, using the triblock copolymer P123 as a surfactant. An increased monomer concentration and the suppression of aggregation of the dye molecules were observed using spectral absorption and fluorescence measurements. The micellation of P123 was studied using differential scanning calorimetry. The optical and thermal data suggest that this micellation process leads to a partitioning of Rhodamine 6G in solution and ultimately drives the equilibrium toward monomer retention. Results from a linear partitioning model support this hypothesis and are in qualitative agreement with the experimental data. These findings pave the way for higher concentrations of Rhodamine 6G to be used in aqueous-based dye lasers and also indicate how Rhodamine 6G could be used in solid-state microlaser systems.

Composition-dependent performance of sol–gel host matrices doped with Rh 6G

Laser dye rhodamine 6G (Rh 6G) was incorporated into sol–gel glasses prepared by using three methods: (i) by using HCl as catalyst, (ii) by using HNO 3 as catalyst and (iii) by using HNO 3 as catalyst and formamide as drying control chemical additive (DCCA). The performance of these sol–gel matrices as hosts was evaluated by studying the absorption/fluorescence behavior of the dye-doped solids with elapsed time. The best performance of Rh 6G, as far as its absorption/fluorescence properties are concerned, was found in the host matrix prepared by using formamide as DCCA along with catalyst HNO 3.

Eight-position substitution effects on laser action of the 1,3,5,7-tetramethyl-2,6-diethyl pyrromethene-BF_2 complexes

We measured laser-action properties of some novel eight-position substituted 1,3,5,7-tetramethyl-2,6-diethyl pyrromethene-BF2 complexes in a Littman-type cavity pumped by the second harmonic of a Q-switched Nd:YAG laser. The substitution effects were investigated by comparing the spectroscopic and laser-action properties of various eight-position substituted complexes, such as absorption, excitation, and fluorescence emission, and triplet–triplet absorption spectra, dye-laser wavelength-tuning spectra, and output-pulse energy versus the pump-laser energy. The results showed that 1,3,5,7-tetramethyl-2,6-diethyl pyrromethene-BF2 complexes with phenyl, p-methoxyphenyl, and p-fluorophenyl substituted at the eight-position outperformed the commercially available benchmark laser dye Rhodamine 6G (Rh6G) in fluorescence quantum yields, laser efficiency, and laser wavelength-tuning range.

Patterned Block-Copolymer-Silica Mesostructures as Host Media for the Laser Dye Rhodamine 6G

Rhodamine 6G-doped mesostructured silica is prepared by an acidic sol−gel route using poly-b-poly(propylene oxide)-b-poly(ethylene oxide) (EOx−POy−EOx) block copolymer surfactants. Using low-refrac...

Tunable stimulated-Brillouin-scattering resonator started by feedback provided by Bragg scattering from the dynamic grating within an active medium

We report a tunable stimulated-Brillouin-scattering resonator that does not require a starting mirror or a wavelength selector. The resonator is based on the Bragg scattering from the dynamic grating within the active medium itself. The laser dye (Rhodamine 6G dissolved in ethanol) was utilized as the active medium and was pumped by a frequency-doubled Nd:YAG laser. The quality factor (M(2)) of the output beam was 2.2. A single short pulse (<1 ns) with a pumping efficiency of ~4% was observed.

Mirrorless lasing from mesostructured waveguides patterned by soft lithography

Mesostructured silica waveguide arrays were fabricated with a combination of acidic sol-gel block copolymer templating chemistry and soft lithography. Waveguiding was enabled by the use of a low-refractive index (1.15) mesoporous silica thin film support. When the mesostructure was doped with the laser dye rhodamine 6G, amplified spontaneous emission was observed with a low pumping threshold of 10 kilowatts per square centimeter, attributed to the mesostructure's ability to prevent aggregation of the dye molecules even at relatively high loadings within the organized high-surface area mesochannels of the waveguides. These highly processible, self-assembling mesostructured host media and claddings may have potential for the fabrication of integrated optical circuits.

SOLVENT EFFECT ON ABSOLUTE FLUORESCENCE QUANTUM YIELD OF RHODAMINE 6G DETERMINED USING TRANSIENT THERMAL LENS TECHNIQUE

Dual beam thermal lens technique is successfully employed for the determination of absolute fluorescence quantum yield of rhodamine 6G laser dye in different solvents. A 532 nm radiation from a Q-switched Nd:YAG laser was used for the excitation purpose. The fluorescence quantum yield values are found to be strongly influenced by environmental effects. It has been observed that fluorescence yield is greater for rhodamine 6G in ethylene glycol system than in water or in methanol. Our results also indicate that parameters like concentration of the dye solution, aggregate formation and excited state absorption affect the absolute values of fluorescence yield significantly.

Persistent spectral hole burning and water content in -doped aluminosilicate glasses

Persistent spectral hole burning (PSHB) was investigated in -doped glass prepared by the sol-gel method. The hole was burned in the line of the ions using a rhodamine 6G dye laser at 77 K, the hole area of which was proportionally increased with the content of OH groups surrounding the ions. The local environment of the ions in glass was examined from the fluorescence line narrowing spectra of the transition. The three splitting energies of the level diverged with the increase of the excitation energy. It was concluded that the PSHB was formed by optically changing the bonding feature of proton in the coordinating sphere of the ions into the activated state, the barrier height of which was estimated as 0.3 eV.

Laser lithotripsy of difficult bile duct stones: results in 60 patients using a rhodamine 6G dye laser with optical stone tissue detection system

Introduction—Laser lithotripsy of bile duct stones has become a widely accepted endoscopic treatment modality for giant, impacted, or very hard stones. The procedure is usually carried out under direct endoscopic...

Persistent Spectral Hole Burning in Eu3+-Doped Silicate Glasses Codoping Al3+ and P5+ Ions

Eu3+-doped SiO2, Al2O3−SiO2, and P2O5−SiO2 glasses were prepared by a sol−gel method from metal alkoxides, and their persistent spectral hole burning (PSHB) properties were investigated in relation to the local environment of the Eu3+ ions in glass. Fluorescence line narrowing spectra indicated that Eu3+ clustering occurred in SiO2 glass. The addition of Al2O3 or P2O5 promoted better dispersion of Eu3+ in the glass matrix, though two sites for Eu3+ ions seemed to exist in Al2O3−SiO2 glass. The holes were burned in the 7F0 → 5D0 line of the Eu3+ ions using a Rhodamine 6G dye laser, the hole area of which increased proportionally with the content of hydroxyl groups. The holes that were burned by the photoinduced rearrangement of the OH bonds were thermally refilled and the barrier height of the burnt-state was determined as 0.14, 0.30, and 0.40 eV for P2O5−SiO2, SiO2, and Al2O3−SiO2 glass, respectively.

Tunable Ultrashort Pulse Generation from a Waveguided Laser with Premixed-Dye-Doped Plastic Film

A highly compact ultrashort pulse generator is proposed and demonstrated with a poly-methylmethacrylate (PMMA) waveguide doped with a mixture of laser dye (Rhodamine 6G) and saturable absorber (DODCI). A series of spikes with a pulse duration of 20–30 ps was generated by a distributed feedback dye laser pumped by a ns Nd:YAG laser. First, the spikes were shortened by passive Q-switching effect of the saturable absorber. Then they were compressed to 9 ps FWHM by passing a pulse compressor having an alternative chain of amplifier and saturable absorber integrated on the same waveguide. Performances of both devices were evaluated by calculation and confirmed experimentally.

Utilization of the yellow component of a copper-vapor laser for extending the tuning range of a Rhodamine 6G dye laser by use of an additional dye in a novel coupled resonator scheme

We demonstrate the use of both 510.6- and 578.2-nm components and the extension of the tuning range of a Rhodamine 6G dye laser in a novel coupled resonator scheme. Rhodamine 6G is pumped by 510.6-nm light in one resonator and Sulforhodamine B is pumped by 578.2 nm in the other. The spectral tuning range of 564-609 nm of the Rhodamine 6G laser is extended up to 640 nm. A two-mirror arrangement ensures continuous tuning across the spectral ranges of the two dyes by rotation of a single plane mirror.

Flashlamp pumped polymer dye laser containing Rhodamine 6G

Polymeric rods incorporating the laser dye Rhodamine 6G in a copolymer of hydroxypropyl acrylate and methylmethacrylate have been shown to lase under flashlamp excitation. The rods exhibit high bulk transmission levels, coupled with positive lensing characteristics, that have enabled output energies up to 354 mJ/pulse with a 0.14% energy efficiency to be demonstrated in a preliminary study.

High-temperature persistent spectral hole burning of Eu3+-doped SiO2 glass prepared by the sol-gel process

Persistent spectral hole burning was observed at temperatures higher than 77 K in SiO2 glass doped with the Eu3+ ions. The Eu3+-doped SiO2 glass was prepared using the sol-gel process of Si(OC2H5)4 and EuCl3⋅6H2O. A persistent spectral hole was burned in the excitation spectrum of the F07→5D0 transition of Eu3+ using a Rhodamine 6G dye laser, of which the hole width and depth were 1.6 cm−1 and ∼20% of the total intensity, respectively, at 77 K. Hole depth decreased with increasing temperature and disappeared above ∼130 K. A possible mechanism for the hole burning is related to the local structure around Eu3+ and the residual OH and H2O in the glass.