Solid-state dye laser with moiré gratings

We fabricated distributed-feedback (DFB) solid-state dye lasers with moiré gratings. We formed a moiré grating pattern by superimposing two grating patterns with a rotation angle. The moiré gratings were fabricated by an “etchless” process utilizing a two-beam interference method. The gratings were coated with solidified rhodamine-B. The five laser devices were pumped with the second harmonic generation of a Nd:YAG laser and we obtained narrow-banded laser oscillations at 590, 600, 610, 620, and 630 nm wavelength. Full widths at half maximum of laser spectra were less than 0.5 nm. The results indicated that a moiré fringe can function as a resonator of DFB solid-state dye lasers.     

Photo-induced reorientation of molecules in dye micro crystals

Upon massive generation of anisotropic grains of azo dye methyl orange in a gelatin film exposed to active polarized light, a cluster of micro crystals with optical axes of similar orientations has been produced. The anisotropy observed has been found to disappear under exposure to active natural light.     

HF-based clad etching of fibre Bragg grating and its utilization in concentration sensing of laser dye in dye–ethanol solution

This paper presents a fibre Bragg grating (FBG) based sensor to study the concentration of laser dye in dye–ethanol solution. The FBG used in this experiment is indigenously developed using 255 nm UV radiations from copper vapour laser. The cladding of the FBG was partially removed using HF-based etching to make FBG sensitive to changes in the surrounding refractive index. The experimental results on the shift of the Bragg peak wavelength with HF etching and different dye concentration in ethanol are presented. The Bragg wavelength shifted from 1534.670 nm to 1534.225 nm in 30 min and from this point to 1533.97 in the next 2 min. The clad-etched Bragg peak shifted almost linearly from 1534.056 nm to 1534.162 nm as surrounding dye concentration in ethanol changes from 0 mM to 1.5 mM. It was observed that sensitivity depends on the concentration of the solution and found to be 70 pm/mM.     

Nonlinear optical properties of a self-organized dye thin film

A self-organized thin film of a cyanine dye is fabricated by the spin-coating technique and is characterized by ultraviolet-visible spectroscopy,infrared(IR)spectroscopy,small-angle X-ray diffraction,ellipsometer, and atomic force microscopy(AFM).The nonlinear optical properties of the thin films are investigated by degenerate four wave mixing(DFWM)technique.The cyanine dye thin film sample exhibits high optical nonlinearities(X~(3)=2.55×10~(-12)esu),and the mechanism is analyzed by the exciton coupling theory.     

Diode-pumped distributed-feedback dye laser with an organic–inorganic microcavity

We present a diode-pumped microcavity dye laser composed of a top organic reflector and a bottom inorganic reflector. The top organic reflector consists of alternate thin films of cellulose acetate and poly(N-vinylcarbazole) doped with coumarin 540A to construct a distributed-feedback (DFB) resonator. Pumped directly by an InGaN-based blue laser diode (LD) with a pulse duration of 4 ns, the microcavity dye laser exhibited a single-mode oscillation at 563 nm with a threshold pump LD power of 290 mW/pulse. The emission of the microcavity dye laser was measured through an optical fiber, resulting in a peak power of 2.5 mW for a pump LD power of 320 mW. PACS  42.55.Mv; 42.55.Sa; 42.55.Xi     

Generation of new longitudinal modes in an amplifying dye solution

A novel phenomenon is reported for the first time that the generation of the newlongitudinal modes in amplifying multi-longitudinal mode laser in a dye amplifier.The newmodes are located on the violet side within the gain band of the amplifing medium.The phe-nomenon is explained by the theory of third-order nonlinear polarization in the case of four-wave resonances.The intensity of the new modes created are comparable with or even higherthan that of the original modes.The effect can be expected to serve as a new method for ex-tention of spectral tuning ranges of laser.     

Influence of scattering on superluminescence in composites dye solution – nanoparticles

Spectral and energy luminescence characteristics of R6G dye solutions in ethanol with addition of Ag nanoparticle suspensions in different aggregate states are experimentally investigated. It is demonstrated that incorporation of non-aggregated and aggregated nanoparticles causes the superluminescence thresholds in R6G solutions to decrease. It is established that the optical properties of the laser beam propagation channel are transformed when low-power (20 mW) cw laser radiation passes through the suspension of nanoparticles. This is manifested through the occurrence of a region with enhanced nanoparticle density in the laser beam center, on which diffraction of laser radiation is observed.     

Theoretical study on the laser gain of a multi-stage dye laser amplifier

Theoretical studies on laser gain of a multi-stage dye laser amplifier are presented in this paper. The resultsshow that the influences of amplified spontaneous emission(ASE)and nonlinear absorption of excited-state on the gain are different for different input laser energies and gains. A threshold input intensityexists for a specific system. If the imput intensity is higher than the threshold, the nonlinear absorptionof excited-state will be the main cause for gain decrease. Otherwise, the ASE is the main cause. A newscheme is proposed to calculate the gain of the amplifier by the comparison of the input intensity with theeffective saturation intensity and the choice of the calculation gain method.     

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.     

Optimizing two-photon fluorescence of Coumarin dye by combined temporal–spatial pulse shaping

Two-photon fluorescence (TPF) process is an important research subject and can be optimized by pulse shaping techniques. In addition to temporal femtosecond pulse shaping by spectral phase modulation, we take into account of spatial configuration in the shaping process. The TPF of Coumarin 500 increases 40% with this additional modulation step. This spatial modulation results in not only transverse spatial profile variation but also effect of temporal redistribution at focus. We show that this spatial modulation is an important dimension for pulse shaping and optimization for TPF.     

Multi-responsive poly(N-isopropylacrylamide) hydrogel with D-π-A type dye

To get a multi-responsive polymer hydrogel, metal sensible and acid/base-switchable D-π-A type dye monomer was synthesized first. The synthesized electron donor-π-conjugated-electron acceptor (D-π-A) type dye monomer 3 was investigated with not only the selective Ni²⁺ and Cu²⁺ metal ion sensing effects, but also an acid/base unit sensing effects in optical properties with UV-vis absorption and fluorescence emission. A thermo-responsive poly(NIPAM-co-dye) copolymer with D-π-A type dye was prepared by typical radical copolymerization. The LCST behavior was investigated by UV-vis spectroscopy, which allows the measurement of the phase transition from 20 to 50 °C in an aqueous solution. The poly(NIPAM-co-dye) copolymer also exhibited color change when not only Ni²⁺ or Cu²⁺ cations were used but also when an acid/base unit was used. The morphology of the internal matrix structure of the poly(NIPAM-co-dye) hydrogel was observed by SEM.     

Solvent effects on structure and optical properties of a D- π-A azobenzene dye

Time-dependent hybrid density functional theory in combination with Onsager reaction field model and super-molecular model has been applied to study solvent effects on the geometrical and electronic structures, as well as one/two-photon absorption properties, of 4-（N-（2-hydroxyethyl）-N-methyl）-amino-4＇-nitroazobenzene. It is found that the short-range interaction has a large effect on the electronic structure of the solute molecule, namely, large red-shift of the maximum one-photon absorption is induced by hydrogen bonding. The solute molecule has a large two-photon absorption cross section, which is enhanced by the solvent effect. The computational results are in good agreement with measurements.[第一段]     

Continuous wave dye laser excitation spectroscopy CaF A2Πr-X2Σ+

Excitation spectra for the CaF A²Π-X²Σ(0, 0), (1, 1), and (1, 0) bands have been observed and assigned. The rotational analysis of the CaF A-X and B-X bands by B. S. Mohanty and K. N. Upadhya [Ind. J. Pure Appl. Phys.5, 523 (1967)] is shown to be incorrect. Because it is possible to make independent rotational assignments of each line in an excitation spectrum by observing frequency differences and relative intensities in photoluminescence spectra, tunable laser excitation spectroscopy promises less ambiguity than traditional techniques for assignment of dense, badly overlapped spectra.The following spectroscopic constants (in cm^?1) are obtained for the CaF A²Π and X²Σ states. Numbers in parentheses correspond to three standard deviations uncertainty in the last digit.

     

15.

Surface-enhanced resonance Raman study of avidin–dye interactions: A model for chromophore-containing proteins     

Fan Ni  Therese M. Cotton 《Journal of Raman spectroscopy : JRS》1988,19(6):429-438

Resonance Raman (RR) and surface-enhanced resonance Raman (SERR) spectroscopy were used to study the behavior of 2-(4′-hydroxyphenylazo)benzoic acid (HABA) at different pH values (2.7–11.8) in solution and bound to avidin. Major changes in the RR spectrum of the dye are observed near pH 8.0 and 3.0. These pH values are close to the pK_a values for the phenolic and carboxylic acid functional groups of HABA and reflect deprotonation of these groups. In addition, however, tautomeric forms of the dye are possible within each pH range and these can be identified from the characteristic vibrational modes of the azo and hydrazone forms of HABA. Similar changes in the SERR spectrum of HABA were also observed as a function of pH. However, a comparison of the RR and SERR spectra has shown that the tautomeric equilbrium is shifted toward the hydrazone form on the Ag surface compared with the effect in solution. The RR and SERR spectra of the HABA-avidin complex are nearly identical and indicative of the hydrazone form of the dye. Hence the complex is not dissociated on the Ag surface. This finding is encouraging with regard to the application of SERR techniques to the study of native proteins containing chromophores.     

16.

Ultrasonically induced ZnO–biosilica nanocomposite for degradation of a textile dye in aqueous phase     

《Ultrasonics sonochemistry》2016

In the present study, a porous clay-like support with unique characteristics was used for the synthesis and immobilization of ZnO nanostructures to be used as sonocatalyst for the sonocatalytic decolorization of methylene blue (MB) dye in the aqueous phase. As a result, the sonocatalytic activity of ZnO–biosilica nanocomposite (77.8%) was higher than that of pure ZnO nanostructures (53.6%). Increasing the initial pH from 3 to 10 led to increasing the color removal from 41.8% to 88.2%, respectively. Increasing the sonocatalyst dosage from 0.5 to 2.5 g/L resulted in increasing the color removal, while further increase up to 3 g/L caused an obvious drop in the color removal. The sonocatalysis of MB dye over ZnO–biosilica nanocomposite was temperature-dependent. The presence of methanol produced the most adverse effect on the sonocatalysis of MB dye. The addition of chloride and carbonate ions had a negligible effect on the sonocatalysis, while the addition of persulfate ion led to increasing the color removal from 77.8% to 99.4% during 90 min. The reusability test exhibited a 15% drop in the color removal (%) within three consecutive experimental runs. A mineralization efficiency of 63.2% was obtained within 4 h.     

17.

New organic–inorganic hybrid matrices doped with rhodamine 6G as solid-state dye lasers     

A. Costela  I. García-Moreno  C. Gómez  O. García  R. Sastre 《Applied physics. B, Lasers and optics》2002,75(8):827-833

We report on the laser action of rhodamine 6G (Rh6G) incorporated into new hybrid organic–inorganic monolithic materials. The synthesis of these materials proceeded via the simultaneous sol-gel process of the inorganic part (tetraethoxysilane or tetramethoxysilane) and the free-radical polymerization of an organic monomer part (2-hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate and a 1:1 v/v copolymer of this monomer with methyl methacrylate). The wt. % proportion of the alkoxide was systematically varied in each organic formulation, and the effect of each organic–inorganic composition on the lasing properties of Rh6G was evaluated. The laser samples were transversely pumped and the influence on the laser action of dye concentration, pump wavelength and pump repetition rate was analyzed. Lasing efficiencies of up 26% and good stabilities, with a 90% drop in the initial laser output of up to 12000 pump pulses at 2.5 Hz, were obtained when the samples were pumped at 355 nm with 5.5 mJ/pulse from the third harmonic of a Q-switched Nd:YAG laser. Received: 31 July 2002 / Revised version: 14 October 2002 / Published online: 20 December 2002 RID="*" ID="*"Corresponding author. Fax: +34-91/564-4853, E-mail: ogarcia@ctp.csic.es     

18.

Oriental behaviour of some homologues of 4-n-pentyl-phenylthio-4′-n-alkoxybenzoate doped with dichroic dye     

D. Bauman  A. Zięba  E. Mykowska 《Opto-Electronics Review》2008,16(3):244-250

The long-range orientational order of three members of 4-n-pentylphenylthio-4′-n-alkoxybenzoate series doped with a dichroic dye was studied by means of electronic absorption and fluorescence measurements. The order parameters <P₂> and <P₄> as well as the orientational distribution function were determined on the basis of absorption and emission spectra of linearly polarized light recorded as a function of temperature in the nematic, smectic A, and smectic C phases. An influence of the dye molecular structure on the orientational order of the dye/liquid crystal mixture was observed. Moreover, the dependence of the order parameter values on the length of the alkoxy chain in liquid crystal molecules was found. It was shown that the order parameter <P₄>, obtained from fluorescence measurements, can be helpful in recognizing the second-order or weakly first-order transitions between various liquid crystalline phases.     

19.

Impact of cavity symmetry on mode suppression and increase of free spectral range in solid-state dye microlaser     

Sergei Popov  Sebastien Ricciardi  Ari T.Friberg  Sergey Sergeyev 《中国光学快报(英文版)》2007,(11)

We describe modeling the solid-state dye laser with the microcavity size comparable to light wavelength. Certain symmetry in the allocation of gain material leads to depletion of odd longitudinal modes that, in turn,increases the tunability range of the microlaser.We provide simple physical explanation for the modeling results.     

20.

Theoretical study of fluorescence resonant energy transfer dynamics in individual semiconductor nanocrystal–DNA–dye conjugates     

Guangcun Shan  Shuying Bao  Chan-Hung Shek  Wei Huang 《Journal of luminescence》2012,132(6):1472-1476

Motivated by recent experimental studies of fluorescence resonant energy transfer (FRET), we consider the influence of the temperature-dependent microscopic spectral overlap and relative orientation of the transition dipoles of fluorophores on the nanosecond dynamics of photon statistics and energy transfer efficiency in semiconductor nanocrystal–DNA–organic dye conjugates using Monte-Carlo simulations. Our calculated mean energy transfer efficiencies are found to be well consistent with those measured in experiment at low temperatures. For the higher temperatures, our results demonstrate that the use of Förster radius estimated from the isotropic dynamic average value of 2/3 for the orientation parameter term may lead to overestimation of energy transfer efficiency for the cases of the rigid arrangement of fluorophore transition moments, and thereby deteriorate the precision of the analysis of donor–acceptor distances. Our theoretical results here underline the importance of a detailed understanding of the microscopic picture of FRET for exploiting this spectroscopic technique in various nano- and bio-applications.     

	$\text{X}{}^2\text{Σ}$		$\text{A}{}^2\text{Π}$
$\text{ν}{}_{00}$	0	${}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$	16493.1(6)
		${}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$	16565.6(6)
$\text{Δ}\text{G(}\text{1}\text{2}\text{)}$	581.1(9)	${}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$	586.8(9)
$\text{B}{}_{\mathrm{e}}$	0.3385(11)		0.3436(12)
$\text{B}{}_{\mathrm{e}}\text{(}\text{Ω}\text{=}\text{3}\text{2}\text{) ? B}{}_3\text{(}\text{Ω}\text{=}\text{1}\text{2}\text{)}$	—		0.00312(21)
α	0.00255(48)		0.00283(45)
$\text{D(}\text{estimated}\text{)}$	4.44 × 10?7		4.55 × 10?7
γ(spin-spin)	|γ| < 3 × 10?3		—
$\text{A}{}_0\text{(}\text{spin-orbit}\text{)}$	—		73.4(9)
$\text{p(}\text{lambda doubling}\text{)}$	—		?0.045(4)

Surface-enhanced resonance Raman study of avidin–dye interactions: A model for chromophore-containing proteins

Resonance Raman (RR) and surface-enhanced resonance Raman (SERR) spectroscopy were used to study the behavior of 2-(4′-hydroxyphenylazo)benzoic acid (HABA) at different pH values (2.7–11.8) in solution and bound to avidin. Major changes in the RR spectrum of the dye are observed near pH 8.0 and 3.0. These pH values are close to the pK_a values for the phenolic and carboxylic acid functional groups of HABA and reflect deprotonation of these groups. In addition, however, tautomeric forms of the dye are possible within each pH range and these can be identified from the characteristic vibrational modes of the azo and hydrazone forms of HABA. Similar changes in the SERR spectrum of HABA were also observed as a function of pH. However, a comparison of the RR and SERR spectra has shown that the tautomeric equilbrium is shifted toward the hydrazone form on the Ag surface compared with the effect in solution. The RR and SERR spectra of the HABA-avidin complex are nearly identical and indicative of the hydrazone form of the dye. Hence the complex is not dissociated on the Ag surface. This finding is encouraging with regard to the application of SERR techniques to the study of native proteins containing chromophores.     

Ultrasonically induced ZnO–biosilica nanocomposite for degradation of a textile dye in aqueous phase

In the present study, a porous clay-like support with unique characteristics was used for the synthesis and immobilization of ZnO nanostructures to be used as sonocatalyst for the sonocatalytic decolorization of methylene blue (MB) dye in the aqueous phase. As a result, the sonocatalytic activity of ZnO–biosilica nanocomposite (77.8%) was higher than that of pure ZnO nanostructures (53.6%). Increasing the initial pH from 3 to 10 led to increasing the color removal from 41.8% to 88.2%, respectively. Increasing the sonocatalyst dosage from 0.5 to 2.5 g/L resulted in increasing the color removal, while further increase up to 3 g/L caused an obvious drop in the color removal. The sonocatalysis of MB dye over ZnO–biosilica nanocomposite was temperature-dependent. The presence of methanol produced the most adverse effect on the sonocatalysis of MB dye. The addition of chloride and carbonate ions had a negligible effect on the sonocatalysis, while the addition of persulfate ion led to increasing the color removal from 77.8% to 99.4% during 90 min. The reusability test exhibited a 15% drop in the color removal (%) within three consecutive experimental runs. A mineralization efficiency of 63.2% was obtained within 4 h.     

New organic–inorganic hybrid matrices doped with rhodamine 6G as solid-state dye lasers

We report on the laser action of rhodamine 6G (Rh6G) incorporated into new hybrid organic–inorganic monolithic materials. The synthesis of these materials proceeded via the simultaneous sol-gel process of the inorganic part (tetraethoxysilane or tetramethoxysilane) and the free-radical polymerization of an organic monomer part (2-hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate and a 1:1 v/v copolymer of this monomer with methyl methacrylate). The wt. % proportion of the alkoxide was systematically varied in each organic formulation, and the effect of each organic–inorganic composition on the lasing properties of Rh6G was evaluated. The laser samples were transversely pumped and the influence on the laser action of dye concentration, pump wavelength and pump repetition rate was analyzed. Lasing efficiencies of up 26% and good stabilities, with a 90% drop in the initial laser output of up to 12000 pump pulses at 2.5 Hz, were obtained when the samples were pumped at 355 nm with 5.5 mJ/pulse from the third harmonic of a Q-switched Nd:YAG laser. Received: 31 July 2002 / Revised version: 14 October 2002 / Published online: 20 December 2002 RID="*" ID="*"Corresponding author. Fax: +34-91/564-4853, E-mail: ogarcia@ctp.csic.es     

Oriental behaviour of some homologues of 4-n-pentyl-phenylthio-4′-n-alkoxybenzoate doped with dichroic dye

The long-range orientational order of three members of 4-n-pentylphenylthio-4′-n-alkoxybenzoate series doped with a dichroic dye was studied by means of electronic absorption and fluorescence measurements. The order parameters <P₂> and <P₄> as well as the orientational distribution function were determined on the basis of absorption and emission spectra of linearly polarized light recorded as a function of temperature in the nematic, smectic A, and smectic C phases. An influence of the dye molecular structure on the orientational order of the dye/liquid crystal mixture was observed. Moreover, the dependence of the order parameter values on the length of the alkoxy chain in liquid crystal molecules was found. It was shown that the order parameter <P₄>, obtained from fluorescence measurements, can be helpful in recognizing the second-order or weakly first-order transitions between various liquid crystalline phases.     

Impact of cavity symmetry on mode suppression and increase of free spectral range in solid-state dye microlaser

We describe modeling the solid-state dye laser with the microcavity size comparable to light wavelength. Certain symmetry in the allocation of gain material leads to depletion of odd longitudinal modes that, in turn,increases the tunability range of the microlaser.We provide simple physical explanation for the modeling results.     

Theoretical study of fluorescence resonant energy transfer dynamics in individual semiconductor nanocrystal–DNA–dye conjugates

Motivated by recent experimental studies of fluorescence resonant energy transfer (FRET), we consider the influence of the temperature-dependent microscopic spectral overlap and relative orientation of the transition dipoles of fluorophores on the nanosecond dynamics of photon statistics and energy transfer efficiency in semiconductor nanocrystal–DNA–organic dye conjugates using Monte-Carlo simulations. Our calculated mean energy transfer efficiencies are found to be well consistent with those measured in experiment at low temperatures. For the higher temperatures, our results demonstrate that the use of Förster radius estimated from the isotropic dynamic average value of 2/3 for the orientation parameter term may lead to overestimation of energy transfer efficiency for the cases of the rigid arrangement of fluorophore transition moments, and thereby deteriorate the precision of the analysis of donor–acceptor distances. Our theoretical results here underline the importance of a detailed understanding of the microscopic picture of FRET for exploiting this spectroscopic technique in various nano- and bio-applications.