New efficient laser dye for pulsed and CW operation in the UV

A new laser dye for pulsed and cw operation has been synthesized which can be tuned from 362 nm up to 412 nm. For pulsed excitation with a XeCl excimer laser an energy conversion of 18.5% has been measured at the tuning maximum of the dye; this is the highest efficiency for any known dye in the UV. For cw operation a low laser threshold and a goof efficiency have been observed. The range of tuned cw dye lasers is extended by 30 nm to shorter wavelengths. The dye shows high photochemical stability even at high pump laser power.     

Laser characteristics of a new laser dye: 7-Diethylamino-3-Styryl Benzimidazo (1,2-a) Quinoline

The laser characteristics of a new dye, 7-Diethyl-amino-3-Styryl Benz31 yimidazo (1,2-a) Quinoline (DSBQ) have been investigated in two solvents: DiMethylSulfOxide (DMSO) and DiMethylFormamide (DMF) by excitation with a pulsed nitrogen laser and compared with that of the standard dye rhodamine B. The lasing range of the dye is nearly 40 nm with maxima at 635 nm and 625 nm in DMSO and DMF, respectively. The efficiency of this dye (DSBQ) has been found to be better than half that of rhodamine B.     

Measurement of two-photon excitation cross-section of a new symmetric-type fluorene derivative

A new dye, 2,7-bis(4-methoxystyryl)-9,9-bis(2-ethylhexyl)-9H-fluorene, has been synthesized, which is a d-π-d symmetrical-type fluorene derivative. The two-photon absorption (TPA) of this new dye has been experimentally studied by comparable two-photon-induced fluorescence method. This new dye has a TPA cross-section of at 790 nm/13 fs.     

Efficacite des systemes unidirectionnels utilisables dans les lasers en anneau

A new dye for cw laser operation has been found which can be tuned as low as 390.4 nm. A low threshold and a good efficiency have been observed. The dye showed no photochemical degradation even at high pump laser levels.     

Thermal and Optical Properties of Cyanine Dye for High Density Digital Versatile Disc-Recordable (DVD-R)

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蛋白质与酸性染料相互作用的分光光度研究

分别在酸性碱性介质研究了铬天青S（CAS）,溴甲酚渌（BCG）,溴邻苯三酚红（BPR）和甲基百里酚蓝（MTB）与蛋白质结合的光度性质。在pH 3．8－4．0,蛋白质使CAS和BCG的吸光度降低,在pH 3．8和10．8,蛋白质分别使BOR和MTB最大吸收波长红移10和20nm,并使染料吸光度增大。无论染料吸光度降低或增大,均与蛋白质浓度在一定浓度范围内成正比。初步讨论了蛋白质与染料作用的机理。     

蛋白质与酸性染料相互作用的分光光度研究

分别在酸性和碱性介质研究了铬天青S(CAS),溴甲酚绿(BCG),溴邻苯三酚红(BPR)和甲基百里酚蓝(MTB)与蛋白质结合的光度性质.在pH3.8～4.0,蛋白质使CAS和BCG的吸光度降低,在pH3.8和10.8,蛋白质分别使BPR和MTB最大吸收波长红移10和20nm,并使染料吸光度增大.无论染料吸光度降低或增大,均与蛋白质浓度在一定浓度范围内成正比.初步讨论了蛋白质与染料作用的机理.     

Wavelength dependent resonant nonlinearities in a standard saturable absorber IR26 on picosecond time scale

Nonlinear optical properties of a standard dye IR26 have been studied by using the Z-scan technique to decipher the difference in the mechanism of nonlinear absorption on picosecond time scale at two wavelengths i.e. at 1064 nm and 532 nm. A prominent contribution of nonlinear absorption is observed in the Z-scan profiles at 1064 nm. The dye exhibits the mechanism of self-defocusing at 1064 nm in contrast to that of self-focusing at 532 nm. While the two photon absorption has been found to be the dominant mechanism of reverse saturable absorption at 1064 nm, the mechanism of excited state absorption is operating at 532 nm. Additionally, the optical phase conjugate geometry of degenerate four wave mixing (DFWM) technique has been used to measure the third order nonlinear susceptibility values at 532 nm to compare with those obtained from the Z-scan profiles.     

Synchrotron small angle x-ray scattering study of dye-sensitized／-unsensitized TiO2 nanoparticle colloidal solution

The wide-gap semiconductor TiO_2 nanoparticles with and without dye sensitization have been studied by small angle x-ray scattering using synchrotron radiation. Surface properties of the colloidal TiO_2 nanoparticles have been analysed in terms of the surface fractal dimensions (D_s), showing that D_s changes from 3.25 to 2.34 when TiO_2 nanoparticles are sensitized by ATRA (all-trans-retinoic acid), which reveals that the surface of the particles become relatively smooth after dye sensitization. The size distribution of gyration radius of TiO_2 nanoparticles in the colloids M(R_g) has been successfully determined by the Shull－Roess method. The main peak of M(R_g) for the unsensitized TiO_2 colloid is located at 2.1nm, corresponding to a spherical diameter of 5.4nm, and this value for the ATRA sensitized TiO_2 increases to 2.4nm, indicating a spherical diameter of 6.4nm. Such a size enlargement of TiO_2 nanoparticles suggests that there is a coating of ATRA on the TiO_2 surface, supporting the view that a monolayer of the dye has been attached to the surface of the TiO_2 nanoparticle.     

Dye laser action at 330 nm using benzoxazole: A new class of lasing dyes

Dye laser action has been observed without dispersion elements at 330 nm in phenyl-benzoxazole, the shortest wavelength observed so far in these experimental conditions. Quantum efficiency of laser emission point to benzoxazole as a new class of dye lasers.     

Holograms recorded with red light in dye sensitized dichromated gelatin

We have found that phase holograms can be recorded with He—Ne laser light in dye sensitized dichromated gelatin. This material has excellent resolution, and refractive index changes up to 0.02 have been observed. The sensitivity of dye sensitized dichromated gelatin at 633 nm is about five times less than of dichromated gelatin at 488 nm.     

Color center laser pumped with a DCM dye laser

A CW, DCM dye laser has been used to pump a RbCl:Li crystal in a color center laser. The DCM dye laser was pumped by the 488 nm and 514.5 nm lines of an argon ion laser. When used in a broad band configuration the dye laser had a power output in the TEM₀₀ mode in excess of 600 mW at a wavelength of 655 nm. An output power in excess of 10 mW at 2.73 μm was possible from the RbCl:Li crystal in a Burleigh FCL for an input power of 600 mW at 655 nm. This method of pumping for the RbCl:Li alleviates the need for both argon ion and krypton ion laser pumps for the Burleigh FCL. All three crystals can be pumped to the specification power levels with a single argon ion laser.     

Rutacridone as a Fluorescent Dye for the Study of Pollen

Rutacridone, alkaloid from plant Ruta graveolens was used for the histochemical staining of Hippeastrum hybridum pollen. The rutacridone fluorescence (excited by UV light at 360–380 nm) has been studied with Karnaukhov-constructed microspectrofluorimeters. Nucleus and DNA were stained by this dye in cells and fluoresced by green light with maxima of 530 and 555 nm, respectively. Development of the pollen was analyzed with this dye.     

偶氮染料掺杂高分子薄膜的光谱和光存储性质研究

利用旋涂法,制备了以二乙基胺基〖Ｎ（ＣＨ２ＣＨ３）２〗作为推电子基因、以具有强电负性的羧基（ＣＯＯＨ）作为拉电子基团的推－拉型偶氮染料掺杂的高分子（ＰＭＭＡ）薄膜。在室温下测试了该偶氮染料在溶液和薄膜态的吸收光谱、薄膜态的反射光谱和透过光,发现该薄膜在４００～５５０ｎｍ波长范围内具有强的吸收。在５１４．５ｎｍ光盘静脉测试仪上测试了膜片的静脉光存储性能,结果表明,用低功率Ａｒ＾＋激光（５１４．５ｎ     

紫外新激光染料IBOP的研究

本文介绍一种新合成的化合物IBOP.经在多种染料激光器上测试表明,其激光转换效率高,光化学稳定性好,能溶于多种溶剂.性能优于DPS等相同波段的常用激光染料.IBOP在各种溶剂中的激光调谐范围为388～428nm,激光峰值波长在400nm左右.本文给出了IBOP的荧光光谱、吸收光谱、激光特性、溶剂效应和浓度效应等数据,并作了讨论.     

Properties of two-photon fluorescence and superradiance of a new organic dye C46H51N2B

Linear and nonlinear optical properties of a new organic dye, trans-4-[p-(N-n-butyl-N-n-butylamino)-styryl]-N-methyl-pyridinium tetraphenylborate solution in dimethyl formamide (DMF) have been studied systematically. When excited with mode-locked picosecond 1 064 nm laser beam, intense upconversion fluorescence and superradiance can be obtained. The temporal behaviors of one-photon absorption and two-photon absorption (TPA) fluorescence and superradiance have been studied. The highest upconversion efficiency was found to be 4.1% at a pump energy of 4 mJ. By using an optical parameter amplifier (OPA) as the pump laser, the nonlinear transmittance and upconversion efficiencies of the dye solution at different wavelengths were measured. The strongest linear absorption was found at a wavelength of 930 nm whereas the highest upconversion efficiency was at 1 030 nm. The 100 nm red-shift for the highest upconversion efficiency wavelength compared with the strongest nonlinear absorption are caused by excited state absorption. Received 17 October 2001 and Received in final form 21 December 2001     

Measurement of dye diffusion in agar gel by use of low-coherence interferometry

We demonstrate low-coherence interferometry for diffusion measurements. We have measured the diffusion coefficient of a phthalocyanine dye in 1.5% agar gel with a two-wavelength interferometer; one wavelength was matched to the absorption peak of the dye at 675 nm, while the other, 805 nm, was not affected by the dye. The diffusion coefficient of the dye was found by fitting a mathematical model for the interferometer signal to the measured low-coherence interferometry amplitude. A 95% confidence interval for the diffusion coefficient was found to be D = (2.5 +/- 0.2) x 10(-10) m2/s. The influence of speckle averaging and experiment time on the determination of the diffusion coefficient has been studied. The presented technique allows in situ characterization of diffusion in semitransparent media.     

Photo-physical properties and amplified spontaneous emission of a new derivative of fluorescein

The synthesis of new high-performance dyes and the implementation of new ways of incorporating the organic molecules into the solid host matrices have produced a great deal of activity in the field of solid-state dye lasers. In this article, the new laser dye, 2-(6-allyl-3-oxo-3H-xanthen-9-yl)-benzoic acid ethyl ester [AXBE] has been synthesized, and its chemical structure was confirmed by ¹H NMR, ¹³C NMR, IR and elemental analysis. This new dye was covalently bonded with methyl methacrylate (MMA) and 2-hydroxy ethyl methacrylate (HEMA) copolymer backbone and evaluated as the active medium of the solid-state laser dye. Its optical properties were experimentally investigated. Amplified spontaneous emission (ASE) and photostability were studied by pumping the dye sample with 355 nm (8 ns) pulsed Nd-YAG laser.     

Dopant-enhanced ablation of nitrocellulose by a nitrogen laser

The photoetching behavior of pure nitrocellulose and of nitrocellulose dyed with stilbene-420, coumarin-120 and rhodamine 6G by 337 nm nitrogen laser pulses has been studied. Ablation with a low power nitrogen laser is hereby reported for the first time. A two step photochemical mechanism is proposed to account for the ablation of the pure material. With the addition of dyes strongly absorbing at 337 nm the photoetching rate of nitrocellulose can be increased significantly. This increase is proportional to the molar extinction coefficient of the dye at 337 nm and its concentration in the polymer. The photoetching mechanism and the energy transfer processes from the dye to the polymer are discussed in detail.     

Photophysical properties and laser characteristics of a new rigid aminocoumarin dye lasing in the blue-green region

The photophysical properties of a new dye, 7-Diethyl AminoCoumarin with a Rigid substitution in the 3-position (referred to as DARC) have been studied in three solvents: dioxane, DMF and DMSO. The dye has been found to have a fluorescence quantum efficiency (_fl) between 0.40 and 0.80 in these solvents. The dye-laser performance of this dye has also been investigated in dioxane, DMF and DMSO, under nitrogen-laser pumping and compared with that of the commercially available standard laser dye, Coumarin 515 (C-515). A tuning range of nearly 70 nm was obtained in the blue-green region with an efficiency up to 80% of that of the standard dye. The observed characteristics of the dye are explained in terms of the sructural rigidization of the dye in the 3-position which inhibits the formation of the Twisted Intramolecular Charge Transfer (TICT) conformation in the excited state leading to an enhancement of the _fl and a considerable improvement in the laser performance.Research carried out at U.D.C.T., Bombay, India