Pyrromethene Research Articles

Investigation of energy transfer between PM567:Rh610 dye mixture in modified poly (methyl methacrylate)

In this paper, solid dye samples were prepared by codoping laser dyes Pyrromethene 567 (PM567) as the energy donor and Rhodamine 610 (Rh610) as the energy acceptor into the ethanol modified poly (methyl methacrylate) matrix (MPMMA) to enhance the properties of the solid dye lasers. The fluorescence intensity of the acceptor was enhanced by up to 9 fold with the introduction of the donor molecules. The laser efficiency of the dye mixture doped samples was improved by up to 8 times relative to that of the samples solely doped with the acceptor, and the highest slope efficiency was obtained as 70.4%. The radiative and nonradiative energy transfer rate constants (KR and KNR) were calculated using the Stern–Volmer plots and the acceptor concentration dependence of the radiative and nonradiative transfer efficiencies were also obtained. The KR was three orders of magnitude higher than the KNR, indicating the dominance of the radiative energy transfer mechanism in the present system. The deviation of the Stern–Volmer plot from the linearity demonstrated that both the dynamic and transient quenching mechanism exist in the present energy transfer system.

Fluorescent and laser properties of pyrromethene 567 (PM567) doped into multi-precursors derived gel glasses

In this work, the laser dye PM567 was incorporated into various organically modified silicate gel glasses (ORMOSILs) derived by methyltriethoxysilane (MTES) and vinyltriethoxysilane (VTES) precursors mixed in various ratios. The laser performances of PM567 doped into MTES–VTES-derived ORMOSILs including the laser slope efficiency, threshold and lifetime together with the spectroscopic properties were investigated. Blue-shifts of fluorescent peaks, extended fluorescent lifetime, improved laser efficiency and lifetime of PM567 doped into ORMOSILs derived by mixed precursors of MTES and VTES have been observed, which might related to the microstructures and micro-chemical environment of the dye in ORMOSILs.

Self-curable solid-state elastic dye lasers capable of mechanical stress probing

Herein, a highly sensitive stress probe is reported based on pyrromethene 597 (PM597) doped elastic polydimethylsiloxane films. By sandwiching the dye doped elastic film with two plano dichromatic mirrors, a solid-sate microcavity laser with low laser threshold (~0.2 μJ) is presented as a straightforward probing method for mechanical stress, which is monitored by the laser output spectra, demonstrating a resolution limit higher than 0.01 MPa. The photostability of PM597 doped into the microcavity laser is higher than 7222 GJ/mol, which is among the highest record ever reported to our knowledge and a fast self-recovery on the laser output in less than 1 h, attributed to diffusion of dye molecules is observed, indicating a practical durability for such stress probes.

Investigation of characteristics of solid-state active media based on pyrromethene 567

Lasing characteristics (spectrum, lifetime, and energy) of solid-state active media based on pyrromethene 567 (PM567) in polymethylmethacrylate (PMMA) and hybrid polymers (PMMA–POSS) are investigated. Patterns of changing the lasing characteristics depending on composites and excitation conditions are established. It is demonstrated that the solid-state active media with efficiency and lifetime that are not inferior to solutions can be synthesized on their basis.

Change of Boron Substitution Improves the Lasing Performance of Bodipy Dyes: A Mechanistic Rationalisation

Bodipy laser dyes are highly efficient but degrade rapidly in solution by reacting with in situ generated singlet oxygen ((1)O(2)). To increase the lasing lifetimes of these dyes, we have designed and synthesised two different congeners of the widely studied Pyrromethene 567 (PM567) by substitution at the boron centre and/or at both the boron centre and the meso position. The two new dyes showed high lasing efficiencies with increased photostability. The results of theoretical and pulse radiolysis studies revealed that the substitution at the boron centre reduced the (1)O(2) generation capacity of these dyes as well as their rate of reaction with (1)O(2), thereby enhancing their lifetimes even under lasing conditions.

Photophysics of the analogs of pyrromethene PM 567

The spectral and luminescence properties of a number of pyrromethene (PM) dyes have been investigated. The absorption and luminescence spectra of PM molecules in different solvents are measured. The electronic structure and electronic excited states are calculated by the method of intermediate neglect of differential overlap with special spectroscopic parameterization. The rate constants of photophysical processes are estimated, and the fluorescence quantum yields are calculated. The fluorescence quantum yields of PM I and PM II molecules are found to decrease upon their excitation to the second short-wavelength absorption band. This phenomenon is interpreted.

Effect of emission wavelength on photo-stability of laser dye: experimental and theoretical study

Photo-stability of laser dyes has been an important consideration for dye lasers. In this work, photo-stability of dye and its effect has been investigated as a function of dye laser wavelengths rather than commonly studied photo-chemical degradation pathways upon excitation with pump laser. Here, we report a significant improvement in photo-stability of the liquid dye laser at peak emission wavelength compared to edge wavelengths of the dye gain curve, which was related with an increase in rate of stimulated emission of dye at peak wavelength. Thus, high laser efficiency harmonizes to high photo-stability of the dye at peak wavelength which is useful for the applications of dye lasers. As a representative case, the photo-stability rates of pyrromethene 567 (PM567) dye at different laser emission wavelengths were studied using a 10-Hz Nd-YAG (532 nm) laser-pumped dye laser set-up under lasing and non-lasing conditions. Deterioration of dye laser efficiency on account of photo-degradation of dye molecules was theoretically simulated using a time-dependent rate equation model, which has been found to be in good agreement with the experimental observations.

Energy transfer mechanisms among various laser dyes co-doped into gel glasses

Abstract Various dyes mixtures consisting of perylene red (P-red), pyrromethene 567 (PM567) and coumarin dyes are incorporated into vinyltriethoxysilane (VTES)-derived gel glasses, respectively. Energy transfer processes among dyes are investigated by measuring the time-resolved and steady-state emission spectra, and fluorescence lifetime of each dye. The energy transfer mechanisms are discussed with 4 categories of dye pairs and extended fluorescence lifetime of PM567 and P-red are observed. The radiative and non-radiative nature of the energy transfer processes and their dependence on the donor dye concentration are estimated, paving the way for highly efficient, stable and broadly tunable solid-state dye laser materials.

Random fiber laser of POSS solution-filled hollow optical fiber by end pumping

Random fiber laser is obtained by end pumping a hollow optical fiber (HOF) filled with a dispersive solution of polyhedral oligomeric silsesquioxanes (POSS) nanoparticles and laser dye pyrromethene 597 (PM597) in carbon disulfide (CS2), in which the concentration is 1.5×10−2M for PM597 and 18.5wt% for POSS, respectively. It is found that the pump light at the one end of the liquid core optical fiber (LCOF) can pass the whole length of LCOF because the POSS nanoparticles were dispersed in CS2 at a molecular level (1–3nm) with high stability and without sedimentation. Above the threshold pump energy (∼0.81mJ) the random fiber laser appears coherent and resonant feedback multimode lasing in the weakly scattering system. For the LCOF containing PM597 with the same concentration and no POSS nanoparticles, there occurs only ASE that can be observed under the same experimental condition.

Femtosecond time-resolved ERE-CARS of PM650

We utilize femtosecond time-resolved electronic resonance-enhanced coherent anti-Stokes Raman scattering (ERE-CARS) to investigate new information for pyrromethene 650 (PM650) dye molecules. For this purpose, the vibrational properties of PM650 are registered in diluted solutions of several organisms. We observe a strong Raman vibrational mode with a wavenumber difference of about 48cm−1 in its organic solutions. This may be linked to the intramolecular electron transfer (ICT) process from the aromatic ring to the cyano group in PM650. The influence of the solvent effects on the vibrational dynamics of PM650 is also investigated. The vibrational properties of PM650 dye molecules diluted in polar organic solutions are light solvent-dependent.

Characteristics of xenon-lamp pumped pyrromethene 567-doped dye laser based on polymethylmethacrylater

The solid-state medium containing pyrromethene 567 (PM567) in a polymethylmethacrylate polymer host is shown to lase under the flash lamp excitation. The experimental setup is an ordinary industrial product without special design. The bulk transmission losses, the output energy, and the other lasing properties are compared. The medium with the lowest transmission loss, measured to be 0.392 %/cm at 633 nm, gives a laser output of 130 mJ with a slope efficiency of 0.082%.

Tunable narrow linewidth laser output from PM567 doped nematic liquid crystal under holographic pumping

LC cell injected the mixture of dye pyrromethene 567 (PM567) and nematic liquid crystal (NLC) by capillary action was prepared. Holographic pumping with a Nd:YAG laser (532 nm, 1 Hz, 10 ns) to form gain distributed feedback in the cell, tunable laser output from the cell was investigated. Through changing the intersection angles of the two coherent light beams from 46° to 50°, the tuning range we obtained is about 37 nm (550–587 nm). Additionally, the FWHM of the laser under such experimental setup was less than 0.1 nm even without the resonant cavity, and the threshold of the laser was about 26 μJ, which was very low as we known.

Enhanced laser characteristics of pyrromethene 650 using modified PMMA as solid hosts

Solid-state samples based on modified polymethyl methacrylate (MPMMA) with methanol doped with the dye pyrromethene 650 (PM650) are prepared. The effects of a volume percentage of methanol on the laser characteristics of the sample, including spectra properties, slope efficiency, photostability and tunable properties, are investigated. The broadband dye laser output wavelength is around 655 nm and a highest slope efficiency of 32.23% is achieved. Pumping the samples at a repetition rate of 5 Hz with a pulse energy of as high as 100 mJ (the fluence is 0.26 J/cm2), the longest lifetime (168000 shots) is obtained in the sample (MMA:methanol=18:2), and the corresponding normalized photostability reaches 109.19 GJ/mol. When the sample (MMA:methanol=18:2) is placed in a Shoshan-type oscillator, the narrow-linewidth operation is a continuous tuning range (up to 64 nm). The results indicate that the laser characteristics of solid-state dyes can be greatly enhanced by using modified PMMA with methanol serving as the solid host.

Highly efficient and photostable solid-state dye lasers doped with PM567 with the addition of Tinuvin770

Solid-state dye samples based on polymethyl methacrylate (PMMA) doped with pyrromethene 567 (PM567) with the addition of Tinuvin770 were prepared. The effects of a light stabilizer and concentration on the laser performances of the solid state dye PM567, including spectra properties, slope efficiency and photostability were investigated. The highest slope efficiency 66.6% was obtained in the sample (PM567:Tinuvin770 = 2.0:0.5). The addition of Tinuvin770 resulted in a dramatic enhancement of photo-stability. Pumping the samples at a rate of 5 Hz with a pulse energy as high as 100 mJ (the pump energy density was 0.26 J/cm2), the output energy dropped to half of its initial value after approximate 149500 shots and the normalized photostability reached 97.2 GJ/mol in the sample (PM567:Tinuvin770 = 2:5). All results have shown that a high efficient and photostable solid-state dye laser with the addition of Tinuvin770 can be obtained.

Solid-state dye lasers based on PMMA co-doped with PM597 and PM650

In order to enhance the laser performances, solid-state samples based on polymethyl methacrylate (PMMA) co-doped with pyrromethene 597 (PM597) and pyrromethene 650 (PM650) were prepared. With SHG of Q-switched Nd:YAG laser (532 nm, ∼15 ns) pumping the samples, laser emission from the mixtures of PM597 and PM650 both in liquid solution and incorporated into solid polymeric matrices were investigated. The highest slope efficiency of co-doped solid-state dye samples 30.8% was achieved. Through the dye PM650 being co-doped into the dye PM597, the dye laser output wavelength was extended for the existence of energy transfer from the dye PM597 to the dye PM650.

Distributed feedback dye laser holographically induced in improved organic–inorganic photocurable nanocomposites

Distributed feedback (DFB) lasing in permanent volume transmission gratings formed in a laser dye-doped organic–inorganic nanocomposite has been investigated. DFB laser cavities were fabricated using one-step two-beam holographic exposure of Pyrromethene 567 (PM567) doped photopolymerizable acrylate monomers containing inorganic (LaPO4) nanoparticles. Compared to the formulation previously utilized, the material composition presented provides longer lifetime of the laser. Spectral and polarization properties, input–output and stability characteristics of the laser output have been investigated by varying the material composition and the patterning parameters. DFB lasing emission of the second and the third diffraction orders has been demonstrated. The spectral linewidth of ∼0.08 nm has been observed at a pump energy threshold of about 0.2 μJ/pulse for the second-order DFB lasing when pumped with 532 nm 500 ps laser pulses. Spectral tuning of the lasing output over ∼56 and ∼7 nm was obtained by varying the grating period and the content of inorganic nanoparticles in the polymer matrix, respectively.

High pulse energy output from tunable solid-state dye laser based on MPMMA doped with PM567

Tunable solid-state dye laser sample based on modified polymethyl methacrylate (MPMMA) with methanol co-doped with pyrromethene 567 (PM567) and Coumarin 440 (C440) was prepared. Tunable dye laser output wavelength from 546 to 594 nm was obtained in an oscillator-amplifier configuration. With the input seed laser energy being about 1.5 mJ, the highest dye laser output energy reached 113.9 mJ, and the corresponding conversion slope efficiency was 51.39%. To the best of our knowledge, the tuning range and narrow linewidth dye output energy is the best under the same condition so far. The linewidth for the seed laser and amplified laser were measured with the result of less than 0.2 nm. With the amplified medium being pumped at a repetition rate of 10 Hz with a pulse energy as high as 120 mJ (the fluence was 0.42 J/cm2), the laser output energy dropped to half of its initial value after approximate 43000 pulses.

Solid-state dye lasers based on polymethyl methacrylate modified with methanol

Solid-state dye samples based on modified polymethyl methacrylate with methanol (MPMMA) doped with pyrromethene 567 (PM567) were first prepared. The effects of volume percentage of methanol on the laser performances of the samples, including spectra properties, slope efficiency and photostability were studied. The highest slope efficiency 66.39% was obtained in the sample (MMA:methanol = 16:4). Pumping the samples at a repetition rate of 5 Hz with a pulse energy as high as 100 mJ (the fluence was 0.26 J/cm2), the output energy dropped to half of its initial value after approximate 156720 shots and the corresponding normalized photostability reached 101.86 GJ/mol in the sample (MMA:methanol = 17:3). Our results indicate that it can obtain a high slope efficiency and good photostability for a solid-state dye laser using MPMMA as solid hosts.

High efficiency dye laser with low fluorescence yield pyrromethene dyes: experimental and theoretical studies

A combined experimental and theoretical study of the photo-physical, laser properties and molecular structures of three relatively recent Pyrromethene (PM) class dyes, PM597, PM580 and PM567, have been carried out. Laser characteristics of these three PM dyes were compared with three other widely used Rhodamine (RH) class dyes, RH6G, RHB and KRS, using a narrow-band dye laser setup, transversely pumped by the second harmonic (532 nm) of a Q-switched Nd-YAG laser. In addition to generating comparative data of these dyes for optimal use in dye lasers, we observed that unlike the RH dyes, the PM dyes show high efficiencies and wide tunability, despite the low fluorescence yield and high rate of non-radiative decay. Particularly, PM597 dye, in spite of a very low quantum yield of fluorescence (Φ=0.42), high non-radiative decay rate, and a large distortion from planarity in its excited state, when used in a laser cavity it exhibited similar laser efficiency and a beneficially wider tuning curve in comparison to other two PM dyes. Theoretical studies were carried out applying density functional theory and time-dependent density functional theory (DFT/TDDFT) to obtain new information on ground and the first excited state geometrical parameters of the PM dyes. Good correlation between calculated molecular properties and experimental results was observed for the evolution of the longest wavelength absorption maximum.

Photophysical and laser characteristics of pyrromethene 567 dye: Experimental and theoretical studies

Narrow-band laser performance of alcohol solutions of pyrromethene 567 (PM567) and rhodamine 6G (RH6G) dye was investigated using a home-made GIG-configured dye laser, excited by the second-harmonic radiation (at 532 nm) of a pulsed Nd:YAG laser. Higher laser efficiency was observed with PM567 dye (∼23% peak) in comparison to the commonly used RH6G dye (16.5%), in spite of much lower fluorescence quantum efficiency of the PM567 (0.83) vis-a-vis RH6G (0.98) dye solutions in ethanol. First principle-based electronic structure calculations were performed on PM567 dye in the ground (S0) and excited states (S1) using density functional theory to elucidate the structure and photophysical properties of the dye.