Feasibility of solar-pumped dye lasers

Science.gov (United States)

Lee, Ja H.; Kim, Kyung C.; Kim, Kyong H.

1987-01-01

Dye laser gains were measured at various pump-beam irradiances on a dye cell in order to evaluate the feasibility of solar pumping. Rhodamine 6G dye was considered as a candidate for the solar-pumped laser because of its high utilization of the solar spectrum and high quantum efficiency. Measurements show that a solar concentration of 20,000 is required to reach the threshold of the dye.

Microfluidic Dye Lasers

DEFF Research Database (Denmark)

Kristensen, Anders; Balslev, Søren; Gersborg-Hansen, Morten

2006-01-01

A technology for miniaturized, polymer based lasers, suitable for integration with planar waveguides and microfluidic networks is presented. The microfluidic dye laser device consists of a microfluidic channel with an embedded optical resonator. The devices are fabricated in a thin polymer film...

Computer control of pulsed tunable dye lasers

International Nuclear Information System (INIS)

Thattey, S.S.; Dongare, A.S.; Suri, B.M.; Nair, L.G.

1992-01-01

Pulsed tunable dye lasers are being used extensively for spectroscopic and photo-chemical experiments, and a system for acquisition and spectral analysis of a volume of data generated will be quite useful. The development of a system for wavelength tuning and control of tunable dye lasers and an acquisition system for spectral data generated in experiments with these lasers are described. With this system, it is possible to control the tuning of three lasers, and acquire data in four channels, simultaneously. It is possible to arrive at the desired dye laser wavelength with a reproducibility of ± 0.012 cm -1 , which is within the absorption width (atomic interaction) caused by pulsed dye lasers of linewidth 0.08 cm -1 . The spectroscopic data generated can be analyzed for spectral identification within absolute accuracy ± 0.012 cm -1 . (author). 6 refs., 11 figs

Low-threshold conical microcavity dye lasers

DEFF Research Database (Denmark)

Grossmann, Tobias; Schleede, Simone; Hauser, Mario

2010-01-01

element simulations confirm that lasing occurs in whispering gallery modes which corresponds well to the measured multimode laser-emission. The effect of dye concentration on lasing threshold and lasing wavelength is investigated and can be explained using a standard dye laser model....

Bleaching and diffusion dynamics in optofluidic dye lasers

DEFF Research Database (Denmark)

Gersborg-Hansen, Morten; Balslev, Søren; Mortensen, Asger

2007-01-01

The authors have investigated the bleaching dynamics that occur in optofluidic dye lasers where the liquid laser dye in a microfluidic channel is locally bleached due to optical pumping. They find that for microfluidic devices, the dye bleaching may be compensated through diffusion of dye molecules...

Simulations of longitudinally pumped dye laser amplifier

International Nuclear Information System (INIS)

Takehisa, Kiwamu; Takemori, Satoshi

1995-01-01

Simulations of a copper laser pumped dye laser amplifier and new designs of the longitudinally pumped dye laser amplifier are presented. The simulations take the consideration of the amplified spontaneous emission (ASE). The new designs utilize a center-hole reflector instead of a dichroic mirror. The simulation results indicate that the poor spatial overlap between the pump beam and the dye beam in the transverse pumping not only reduces the laser output power, but also generates ASE strongly. The results also indicate that the longitudinal pumping is as efficient as the transverse pumping. (author)

Design and construction of liquid lasers using organic dyes

International Nuclear Information System (INIS)

Hariri, Akbar.

1984-01-01

Organic dye solution show great promise of obtaining tunable coherent light over the uv, visible and near infrared portion of spectrum. In this paper we describe various pumping schemes of dye molecules. Design, construction and performance of a pulsed dye laser, transversely pumped by a nitrogen laser and wall-ablation flash lamp-pumped dye lasers are the particular examples which are presented in detail

Third-order nonlinear optical studies of anthraquinone dyes using a CW He–Ne laser

International Nuclear Information System (INIS)

Pramodini, S; Poornesh, P

2014-01-01

We present investigations on the third-order optical nonlinearity and optical power limiting of anthraquinone dyes. Z-scan measurements were performed using a continuous wave He–Ne laser at 633 nm wavelength as an excitation source. The nonlinear refraction studies exhibited self-defocusing behavior of the dyes. The nonlinear absorption in the dyes was dominated by a reverse saturable absorption process. Self-diffraction ring patterns were observed due to the change in refractive index and thermal lensing. Increase of the electron donating ability of the substituents resulted in enhanced values of the nonlinear optical parameters, establishing the structure–property relationship. The optical limiting study revealed that the dyes possess a lower limiting threshold and clamping level which is very important for eye and sensor protection. Hence, the dyes investigated here emerge as promising candidates for future opto-electronic and photonic device applications such as optical power limiters. (paper)

Third-order nonlinear optical studies of anthraquinone dyes using a CW He-Ne laser

Science.gov (United States)

Pramodini, S.; Poornesh, P.

2014-05-01

We present investigations on the third-order optical nonlinearity and optical power limiting of anthraquinone dyes. Z-scan measurements were performed using a continuous wave He-Ne laser at 633 nm wavelength as an excitation source. The nonlinear refraction studies exhibited self-defocusing behavior of the dyes. The nonlinear absorption in the dyes was dominated by a reverse saturable absorption process. Self-diffraction ring patterns were observed due to the change in refractive index and thermal lensing. Increase of the electron donating ability of the substituents resulted in enhanced values of the nonlinear optical parameters, establishing the structure-property relationship. The optical limiting study revealed that the dyes possess a lower limiting threshold and clamping level which is very important for eye and sensor protection. Hence, the dyes investigated here emerge as promising candidates for future opto-electronic and photonic device applications such as optical power limiters.

Photoactive dye enhanced tissue ablation for endoscopic laser prostatectomy

Science.gov (United States)

Ahn, Minwoo; Nguyen, Trung Hau; Nguyen, Van Phuc; Oh, Junghwan; Kang, Hyun Wook

2015-02-01

Laser light has been widely used as a surgical tool to treat benign prostate hyperplasia with high laser power. The purpose of this study was to validate the feasibility of photoactive dye injection to enhance light absorption and eventually to facilitate tissue ablation with low laser power. The experiment was implemented on chicken breast due to minimal optical absorption Amaranth (AR), black dye (BD), hemoglobin powder (HP), and endoscopic marker (EM), were selected and tested in vitro with a customized 532-nm laser system with radiant exposure ranging from 0.9 to 3.9 J/cm2. Light absorbance and ablation threshold were measured with UV-VIS spectrometer and Probit analysis, respectively, and compared to feature the function of the injected dyes. Ablation performance with dye-injection was evaluated in light of radiant exposure, dye concentration, and number of injection. Higher light absorption by injected dyes led to lower ablation threshold as well as more efficient tissue removal in the order of AR, BD, HP, and EM. Regardless of the injected dyes, ablation efficiency principally increased with input parameter. Among the dyes, AR created the highest ablation rate of 44.2+/-0.2 μm/pulse due to higher absorbance and lower ablation threshold. Preliminary tests on canine prostate with a hydraulic injection system demonstrated that 80 W with dye injection yielded comparable ablation efficiency to 120 W with no injection, indicating 33 % reduced laser power with almost equivalent performance. In-depth comprehension on photoactive dye-enhanced tissue ablation can help accomplish efficient and safe laser treatment for BPH with low power application.

Solid state microcavity dye lasers fabricated by nanoimprint lithography

DEFF Research Database (Denmark)

Nilsson, Daniel; Nielsen, Theodor; Kristensen, Anders

2004-01-01

propagating TE–TM modes. The laser cavity has the lateral shape of a trapezoid, supporting lasing modes by reflection on the vertical cavity walls. The solid polymer dye lasers emit laterally through one of the vertical cavity walls, when pumped optically through the top surface by means of a frequency...... doubled, pulsed Nd:YAG laser. Lasing in the wavelength region from 560 to 570 nm is observed from a laser with a side-length of 50 µm. In this proof of concept, the lasers are multimode with a mode wavelength separation of approximately 1.6 nm, as determined by the waveguide propagation constant......We present a solid state polymer microcavity dye laser, fabricated by thermal nanoimprint lithography (NIL) in a dye-doped thermoplast. The thermoplast poly-methylmethacrylate (PMMA) is used due to its high transparency in the visible range and its robustness to laser radiation. The laser dye...

Efficiencies of laser dyes for atomic vapor laser isotope separation

International Nuclear Information System (INIS)

Maeda, Mitsuo; Oki, Yuji; Uchiumi, Michihiro; Takao, Takayuki; Igarashi, Kaoru; Shimamoto, Kojiro.

1995-01-01

Efficiencies of 30 laser dyes for the atomic vapor laser isotope separation (AVLIS) are experimentally evaluated with a dye laser pumped by a frequency-doubled Nd:YAG laser. On the other hand, a simulation code is developed to describe the laser action of Rhodamine 6G, and the dependence of the laser efficiency on the pump wavelength is calculated. Following conclusions are obtained by these considerations:space: 1) Pyrromethene 567 showed 16% higher laser efficiency than Rhodamine 6G by 532 nm pumping, and Pyrromethene 556 has an ability to provide better efficiency by green light pumping with a Cu vapor laser; 2) Kiton red 620 and Rhodamine 640, whose efficiencies were almost the same as Rhodamine 6G by 532 nm pumping, will show better efficiencies by two-wavelength pumping with a Cu vapor laser. (author)

The copper-pumped dye laser system at Lawrence Livermore National Laboratory

International Nuclear Information System (INIS)

Hackel, R.P.; Warner, B.E.

1993-01-01

The Lawrence Livermore National Laboratory's (LLNL) Atomic Vapor Laser Isotope Separation (AVLIS) Program has developed a high-average-power, pulsed, tunable, visible laser system. Testing of this hardware is in progress at industrial scale. The LLNL copper-dye laser system is prototypical of a basic module of a uranium-AVLIS plant. The laser demonstration facility (LDF) system consists of copper vapor lasers arranged in oscillator-amplifier chains providing optical pump power to dye-laser master-oscillator-power-amplifier chains. This system is capable of thousands of watts (average) tunable between 550 and 650 mm. The copper laser system at LLNL consists of 12 chains operating continuously. The copper lasers operate at nominally 4.4 kHz, with 50 ns pulse widths and produce 20 W at near the diffraction limit from oscillators and >250 W from each amplifier. Chains consist of an oscillator and three amplifiers and produce >750 W average, with availabilities >95% (i.e., >8,300 h/y). The total copper laser system power averages ∼9,000 W and has operated at over 10,000 W for extended intervals. The 12 copper laser beams are multiplexed and delivered to the dye laser system where they pump multiple dye laser chains. Each dye chain consists of a master oscillator and three or four power amplifiers. The master oscillator operates at nominally 100 mW with a 50 MHz single mode bandwidth. Amplifiers are designed to efficiently amplify the dye beam with low ASE content and high optical quality. Sustained dye chain powers are up to 1,400 W with dye conversion efficiency >50%, ASE content <5%, and wavefront quality correctable to <λ/10 RMS, using deformable mirrors. Since the timing of the copper laser chains can be offset, the dye laser system is capable of repetition rates which are multiples of 4.4 kHz, up to 26 kHz, limited by the dye pumping system. Development of plant-scale copper and dye laser hardware is progressing in off-line facilities

Levitated droplet dye laser

DEFF Research Database (Denmark)

Azzouz, H.; Alkafadiji, L.; Balslev, Søren

2006-01-01

a high quality optical resonator. Our 750 nL lasing droplets consist of Rhodamine 6G dissolved in ethylene glycol, at a concentration of 0.02 M. The droplets are optically pumped at 532 nm light from a pulsed, frequency doubled Nd:YAG laser, and the dye laser emission is analyzed by a fixed grating...

Dye laser with distributed feedback and with pumping by copper-vapor laser

Energy Technology Data Exchange (ETDEWEB)

Mirza, S Yu; Soldatov, A N; Sukhanov, V B

1983-10-01

An experimental study was made for determining the characteristics of dye lasers with distributed feedback, not requiring intricate resonator structures, and the feasibility of their pumping with radiation from a metal-vapor laser. The experiments were performed with five different dyes lasing in the yellow-red (510.6 - 578.2 nm) range of the spectrum: rhodamine 110, 6G, S and ocazine 17,1 in ethyl alcohol solution. The optical equipment included a copper-vapor pumping laser with the gas-discharge tube inside a telescopic resonator of the unstable type. Pumping pulses of 20 ns duration were generated at 510.6 and 578.2 nm wavelengths and a 4 kHz repetition rate. The pumping power was varied by means of an interference filter smoothly adjustable through rotation. The pumping laser beam was focused by a cylindrical lens on the dye cell. At optimum dye concentrations, corresponding to a maximum attainable emission power, dye concentrate was added into the circulation system for determining the dependence of the pumping threshold power on the dye concentration. Also measured were the dependence of the emission efficiency on the pumping power and the tuning range of each dye laser. The efficiency was found to remain constant over the pumping power range from threshold level to eight times higher level. The results reveal different angles of laser beam divergence in the vertical plane and in the horizontal plane, the divergence angle being four times larger in the vertical plane. The conversion efficiency increased, without significant changes in spectral characteristics, with a single annular reflector instead of two reflectors. 9 references, 4 figures, 1 table.

Photoactive dye-enhanced tissue ablation for endoscopic laser prostatectomy.

Science.gov (United States)

Ahn, Minwoo; Hau, Nguyen Trung; Van Phuc, Nguyen; Oh, Junghwan; Kang, Hyun Wook

2014-11-01

Laser light has been widely used as a surgical tool to treat benign prostate hyperplasia (BPH) over 20 years. Recently, application of high laser power up to 200 W was often reported to swiftly remove a large amount of prostatic tissue. The purpose of this study was to validate the feasibility of photoactive dye injection to enhance light absorption and eventually to facilitate tissue vaporization with low laser power. Chicken breast tissue was selected as a target tissue due to minimal optical absorption at the visible wavelength. Four biocompatible photoactive dyes, including amaranth (AR), black dye (BD), hemoglobin powder (HP), and endoscopic marker (EM), were selected and tested in vitro with a customized 532 nm laser system with radiant exposure ranging from 0.9 to 3.9 J/cm(2) . Light absorbance and ablation threshold were measured with UV-Vis spectrometer and Probit analysis, respectively, and compared to feature the function of the injected dyes. Ablation performance with dye-injection was evaluated in light of radiant exposure, dye concentration, and number of injection. Higher light absorption by injected dyes led to lower ablation threshold as well as more efficient tissue removal in the order of AR, BD, HP, and EM. Regardless of the injected dyes, ablation efficiency principally increased with radiant exposure, dye concentration, and number of injection. Among the dyes, AR created the highest ablation rate of 44.2 ± 0.2 µm/pulse due to higher absorbance and lower ablation threshold. High aspect ratios up to 7.1 ± 0.4 entailed saturation behavior in the tissue ablation injected with AR and BD, possibly resulting from plume shielding and increased scattering due to coagulation. Preliminary tests on canine prostate with a hydraulic injection system demonstrated that 80 W with dye injection yielded comparable ablation efficiency to 120 W with no injection, indicating 33% reduced laser power with almost equivalent performance. Due to

Optimum design of a multi-stage dye-laser amplifier pumped with Cu-vapor lasers

International Nuclear Information System (INIS)

Maeda, Mitsuo; Uchiumi, Michihiro

1990-01-01

A numerical simulation code, based on the one-dimensional photon transport equation, was developed and analyzed to evaluate the performances of Rhodamine 6G dye laser amplifiers pumped with Cu-vapor lasers. The upper singlet-state absorption played an important role to determine the efficiency. The simulation code was applied to optimize a multi-stage amplifier system with a pulsed or a CW dye-laser oscillator. The analytical results gave a useful guideline to design a high-power pulsed dye-laser system for atomic uranium enrichment. (author)

Active-passively mode-locked dye laser for diagnosis of laser-produced plasmas

International Nuclear Information System (INIS)

Teng, Y.L.; Fedosejevs, R.; Sigel, R.

1981-03-01

In this report an active-passively mode-locked, flashlamp-pumped dye laser for diagnosis of laser-produced plasmas is described. This dye laser system used as a pulsed light source for high-speed photography of laser-target experiments was synchronized to the ASTERIX III iodine laser pulse with better than 100 ps accuracy. The single pulse energy was 10 μJ, pulse duration less than 10 ps. In 111 shots clear shadowgrams were obtained during a total of 151 target shots, i.e. the system worked well in 74% of the shots. (orig.)

Development of frequency tunable Ti:sapphire laser and dye laser pumped by a pulsed Nd:YAG laser

International Nuclear Information System (INIS)

Yi, Jong Hoon; Horn, Roland; Wendt, K.

2001-01-01

We investigated lasing characteristics of two kinds of tunable laser, liquid dye laser and solid Ti:sapphire crystal laser, pumped by high pulse repetition rate Nd:YAG laser. Dye laser showed drastically reduced pulsewidth compared with that of pump laser and it also contained large amount of amplified spontaneous emission. Ti:sapphire laser showed also reduced pulsewidth. But, the laser conversion pump laser and Ti:sapphire laser pulse, we used a Brewster-cut Pockel's cell for Q-switching. The laser was frequency doubled by a type I BBO crystal outside of the cavity.

Nanoimprinted polymer photonic crystal dye lasers

DEFF Research Database (Denmark)

Christiansen, Mads Brøkner; Smith, Cameron; Buss, Thomas

2010-01-01

Optically pumped polymer photonic crystal band-edge dye lasers are presented. The photonic crystal is a rectangular lattice providing laser feedback as well as an optical resonance for the pump light. The lasers are defined in a thin film of photodefinable Ormocore hybrid polymer, doped...

Development of the plastic solid-dye cell for tunable solid-state dye lasers and study on its optical properties

Energy Technology Data Exchange (ETDEWEB)

Ko, Do Kyeong; Lee, Jong Min; Cha, Byung Heon; Jung, E. C.; Kim, Hyun Su; Lim, Gwon

2001-01-01

we have fabricated solid-state dyes with PMMA and sol-gel materials. We developed single longitudianl mode solid-state dye laser with the linewidth of less than 500MHz. We have constructed a self-seeded laser and observed the increase of the output power because of self-seeding effect. We investigated the operating characteristics of the dualwave laser oscillator and DFDL with solid-state dyes. And we have constructed the 3-color solid-state dye laser oscillator and amplifier system and observed 3-color operation. We also improved the laser oscliiator with disk-type solid-state dye cell which can be translated and rotated with the help of the two stepping motors. With the help of computer control, we could constantly changed the illuminated area of the dye cell and, therefore, were able to achieve long time operation and to use almost the entire region of the solid-state dye cell.

Laser cooling and ion beam diagnosis of relativistic ions in a storage ring

International Nuclear Information System (INIS)

Schroeder, S.

1990-08-01

Particle accelerator and storage ring technology has reached an advanced state, so that different heavy ion storage rings are coming into operation by now, capable of storing even fully stripped ions up to U 92+ . The main purpose of these machines are the accumulation of ions and the ability of improving the beam quality, that is the phase space density of the stored beams. This beam cooling is done successfully by the well established stochastic and electron cooling techniques. A new cooling method, the laser cooling, is taken over from atomic beam and ion trap experiments, where it has yielded extremely low temperatures of atomic samples. As a canditate at storage rings 7 Li + ions are stored in the Heidelberg TSR at 13.3 MeV. The ion beam properties of the metastable fraction like momentum spread, storage time and the influence of residual gas scattering are investigated by colinear laser spectroscopy in the experimental section of the TSR. An optical pumping experiment using two dye laser systems yields information about ion kinematics and velocity mixing processes in the ring. Lifetimes in the order of 100 ms for velocity classes marked in this way show that laser cooling can be applied to the stored 7 Li + beam. In an experimental situation of two strong counterpropagating laser beams, both tuned near resonance, a dramatic reduction of the ion beam momentum spread is observed. With a special geometrical control of laser and ion beam the longitudinal beam temperature is reduced from 260 K to at least 3 K with very high collection efficiency. (orig./HSI) [de

Superthin resonator dye laser with THz intermode frequency separation

International Nuclear Information System (INIS)

Rudych, P D; Surovtsev, N V

2014-01-01

Two-color laser irradiation is considered an effective way to pump THz excitations for numerous scientific and applied goals. We present a design for convenient laser source with THz intermode frequency separation. The setup is based on dye laser with superthin resonator pumped by a subnanosecond pulse laser. It was proven that the superthin resonator dye laser is useful, possesses high stability and high energy conversion, and generates narrow laser modes. The ability of this laser to pump CARS processes for THz vibrations is demonstrated. (letter)

Threshold pump power of a solar-pumped dye laser

Science.gov (United States)

Lee, Ja H.; Kim, Kyung C.; Kim, Kyong H.

1988-01-01

Threshold solar power for dye laser pumping has been determined by measuring the gain of a rhodamine 6G dye laser amplifier at various solar-simulated irradiances on an amplifier cell. The measured threshold was 20,000 solar constants (2.7 kW/sq cm) for the dye volume of 2 x 5 x 40 cu mm and the optimum dye concentration of 0.001 M. The threshold is about one-third of that achievable with a high-intensity solar concentrator.

Investigation of dye laser excitation of atomic systems

International Nuclear Information System (INIS)

Abate, J.A.

1977-01-01

A stabilized cw dye laser system and an optical pumping scheme for a sodium atomic beam were developed, and the improvements over previously existing systems are discussed. A method to stabilize both the output intensity and the frequency of the cw dye laser for periods of several hours is described. The fluctuation properties of this laser are investigated by photon counting and two-time correlation measurements. The results show significant departures from the usual single-mode laser theory in the region of threshold and below. The implications of the deviation from accepted theory are discussed. The atomic beam system that was constructed and tested is described. A method of preparing atomic sodium so that it behaves as a simple two-level atom is outlined, and the results of some experiments to study the resonant interaction between the atoms and the dye laser beam are presented

Unidirectional ring-laser operation using sum-frequency mixing

DEFF Research Database (Denmark)

Tidemand-Lichtenberg, Peter; Cheng, Haynes Pak Hay; Pedersen, Christian

2010-01-01

A technique enforcing unidirectional operation of ring lasers is proposed and demonstrated. The approach relies on sum-frequency mixing between a single-pass laser and one of the two counterpropagating intracavity fields of the ring laser. Sum-frequency mixing introduces a parametric loss for the...... where lossless second-order nonlinear materials are available. Numerical modeling and experimental demonstration of parametric-induced unidirectional operation of a diode-pumped solid-state 1342 nm cw ring laser are presented.......A technique enforcing unidirectional operation of ring lasers is proposed and demonstrated. The approach relies on sum-frequency mixing between a single-pass laser and one of the two counterpropagating intracavity fields of the ring laser. Sum-frequency mixing introduces a parametric loss...

Broad band exciplex dye lasers

International Nuclear Information System (INIS)

Dienes, A.; Shank, C.V.; Trozzolo, A.M.

1975-01-01

The disclosure is concerned with exciplex dye lasers, i.e., lasers in which the emitting species is a complex formed only from a constituent in an electronically excited state. Noting that an exciplex laser, favorable from the standpoint of broad tunability, results from a broad shift in the peak emission wavelength for the exciplex relative to the unreacted species, a desirable class resulting in such broad shift is described. Preferred classes of laser media utilizing specified resonant molecules are set forth. (auth)

Effect of conjugation length on nonlinear optical parameters of anthraquinone dyes investigated using He-Ne laser operating in CW mode

Science.gov (United States)

Pramodini, S.; Poornesh, P.

2014-10-01

We report the studies on third-order optical nonlinearity and optical limiting of anthraquinone dyes. Z-scan technique was employed to evaluate the nonlinear parameters such as nonlinear absorption coefficient βeff and nonlinear index of refraction n2. Continuous wave He-Ne laser was used as the source of excitation. The estimated values of βeff, n2 and χ(3) are of the order of 10-3 cm/W, 10-5 esu and 10-7 esu respectively. The presence of donor and acceptor groups in the structure results in increase in conjugation length. This resulted in the enhancement of nonlinear optical parameters values of the dye. Multiple diffraction rings were observed when the samples were exposed to laser beam due to thermal lensing. Dyes exhibited good optical limiting behavior under the experimental conditions. The results indicate that the dyes investigated here are materialise as candidates for photonics device applications such as optical power limiters.

Comparison of pulsed dye laser versus combined pulsed dye laser and Nd:YAG laser in the treatment of inflammatory acne vulgaris.

Science.gov (United States)

Salah El Din, Manal Mohamed; Samy, Nevien Ahmed; Salem, Amira Eid

2017-06-01

Both pulsed dye laser and combined 585/1064-nm (sequential dual-wavelength PDL and Nd:YAG) laser improves inflammatory skin disorders including acne vulgaris. To compare the efficacy of 585-nm pulsed dye laser versus sequential dual-wavelength PDL and Nd:YAG in treatment of acne vulgaris. Thirty patients with acne vulgaris were treated by PDL alone on half of the face while contra lateral half was treated by combined 585/1064 nm laser. The study showed that inflammatory acne lesions count was significantly reduced by 82.5% (p 0.0001) on PDL sides and by 83.5% (p 0.00001) on combined 585/1064-nm side after 8 weeks, while reduction of non-inflammatory acne lesions was observed at 8 weeks by 58.4% and 71.5% respectively. However, difference between the two modalities was not statistically significant. PDL and combined PDL/Nd:YAG laser treatment were found to be an effective, safe and well-tolerated treatment option for inflammatory and non-inflammatory acne vulgaris.

CW-laser induced microchannels in dye-polymethacrylic acid films

OpenAIRE

M.A. Camacho-López

2007-01-01

In this work we report on the formation of microchannels on dye-polymethacrylic acid films using a cw-laser. A focalized beam of a He-Ne laser (632.8 nm emission line) was used to form microchannels on the films. It was found that there exists a laser power density threshold for a pit formation that depends on the dye concentration. The dimensions of the laser-induced channels are dependent on the laser power density. Microchannel formation in the transparent polymethacrylic acid films was no...

Synthesis of water-soluble, ring-substituted squaraine dyes and their evaluation as fluorescent probes and labels

Energy Technology Data Exchange (ETDEWEB)

Tatarets, Anatoliy L. [SSI ' Institute for Single Crystals' of the National Academy of Sciences of Ukraine, 60 Lenin Ave., Kharkov 61001 (Ukraine); Fedyunyayeva, Irina A. [SSI ' Institute for Single Crystals' of the National Academy of Sciences of Ukraine, 60 Lenin Ave., Kharkov 61001 (Ukraine); Dyubko, Tatyana S. [SSI ' Institute for Single Crystals' of the National Academy of Sciences of Ukraine, 60 Lenin Ave., Kharkov 61001 (Ukraine); Povrozin, Yevgeniy A. [SSI ' Institute for Single Crystals' of the National Academy of Sciences of Ukraine, 60 Lenin Ave., Kharkov 61001 (Ukraine); Doroshenko, Andrey O. [Institute of Chemistry, V.N. Karazin National University, 4 Svobody Sq., Kharkov 61077 (Ukraine); Terpetschnig, Ewald A. [SETA BioMedicals, LLC, 2014 Silver Ct East, Urbana, IL 61801 (United States) and ISS, Inc., 1602 Newton Drive, Champaign, IL 61822 (United States)]. E-mail: ewaldte@juno.com; Patsenker, Leonid D. [SSI ' Institute for Single Crystals' of the National Academy of Sciences of Ukraine, 60 Lenin Ave., Kharkov 61001 (Ukraine); SETA BioMedicals, LLC, 2014 Silver Ct East, Urbana, IL 61801 (United States)

2006-06-16

A series of ring-substituted squaraines absorbing and emitting in the red and NIR spectral region was synthesized and their spectral and photophysical properties (quantum yields, fluorescence lifetimes) and photostabilities were measured and compared to Cy5, a commonly used fluorescent label. The absorption maxima in aqueous media were found to be between 628 and 667 nm and the emission maxima are between 642 and 685 nm. Squaraine dyes exhibit high extinction coefficients (163,000-265,000 M{sup -1} cm{sup -1}) and lower quantum yields (2-7%) in aqueous buffer but high quantum yields (up to 45%) and long fluorescence lifetimes (up to 3.3 ns) in presence of BSA. Dicyanomethylene- and thio-substituted squaraines exhibit an additional absorption around 400 nm with extinction coefficients between 21,500 and 44,500 M{sup -1} cm{sup -1}. These dyes are excitable not only with red but also with blue diode lasers or light emitting diodes. Due to the favourable spectral and photophysical properties these dyes can be used as fluorescent probes and labels for intensity- and fluorescence lifetime-based biomedical applications.

Synthesis of water-soluble, ring-substituted squaraine dyes and their evaluation as fluorescent probes and labels

International Nuclear Information System (INIS)

Tatarets, Anatoliy L.; Fedyunyayeva, Irina A.; Dyubko, Tatyana S.; Povrozin, Yevgeniy A.; Doroshenko, Andrey O.; Terpetschnig, Ewald A.; Patsenker, Leonid D.

2006-01-01

A series of ring-substituted squaraines absorbing and emitting in the red and NIR spectral region was synthesized and their spectral and photophysical properties (quantum yields, fluorescence lifetimes) and photostabilities were measured and compared to Cy5, a commonly used fluorescent label. The absorption maxima in aqueous media were found to be between 628 and 667 nm and the emission maxima are between 642 and 685 nm. Squaraine dyes exhibit high extinction coefficients (163,000-265,000 M -1 cm -1 ) and lower quantum yields (2-7%) in aqueous buffer but high quantum yields (up to 45%) and long fluorescence lifetimes (up to 3.3 ns) in presence of BSA. Dicyanomethylene- and thio-substituted squaraines exhibit an additional absorption around 400 nm with extinction coefficients between 21,500 and 44,500 M -1 cm -1 . These dyes are excitable not only with red but also with blue diode lasers or light emitting diodes. Due to the favourable spectral and photophysical properties these dyes can be used as fluorescent probes and labels for intensity- and fluorescence lifetime-based biomedical applications

Molecular dynamics stimulations to study laser dye aggregation in water (comparison with experiments)

International Nuclear Information System (INIS)

Dare-Doyen, St.; Doizi, D.

2000-01-01

A laser facility consists of dye laser chains where the active medium is composed of fluorescent dyes dissolved in ethanol. The use of water as a solvent would offer two major advantages: greater safety of the laser facility by drastically reducing fire risks, easier design of the laser beam correcting devices required at the end of the dye laser chains, thanks to the properties of water. Unfortunately, laser dyes exhibit poor optical properties in water, due to the formation of dye aggregates. Molecular dynamics simulations were used to study and develop means to prevent this behavior between two charged species. The results were compared with NMR (Nuclear Magnetic Resonance) experiments

Microvascular blood flow dynamics associated with photodynamic therapy, pulsed dye laser irradiation and combined regimens

OpenAIRE

Smith, TK; Choi, B; Ramirez-San-Juan, JC; Nelson, JS; Osann, K; Kelly, KM

2006-01-01

Background and Objectives: Previous in vitro studies demonstrated the potential utility of benzoporphyrin derivative monoacid ring A (BPD) photodynamic therapy (PDT) for vascular destruction. Moreover, the effects of PDT were enhanced when this intervention was followed immediately by pulsed dye laser (PDL) irradiation (PDT/ PDL). We further evaluate vascular effects of PDT alone, PDL alone and PDT/PDL in an in vivo rodent dorsal skinfold model. Study Design/Materials and Methods: A dorsal sk...

Development of high-power dye laser chain

Science.gov (United States)

Konagai, Chikara; Kimura, Hironobu; Fukasawa, Teruichiro; Seki, Eiji; Abe, Motohisa; Mori, Hideo

2000-01-01

Copper vapor laser (CVL) pumped dye laser (DL) system, both in a master oscillator power amplifier (MOPA) configuration, has been developed for Atomic Vapor Isotope Separation program in Japan. Dye laser output power of about 500 W has been proved in long-term operations over 200 hours. High power fiber optic delivery system is utilized in order to efficiently transport kilowatt level CVL beams to the DL MOPA. Single model CVL pumped DL oscillator has been developed and worked for 200 hours within +/- 0.1 pm wavelength stability. Phase modulator for spreading spectrum to the linewidth of hyperfine structure has been developed and demonstrated.

Investigation of the dye concentration influence on the lasing wavelength and threshold for a micro-fluidic dye laser

DEFF Research Database (Denmark)

Helbo, Bjarne; Kragh, Søren; Kjeldsen, B.G.

2003-01-01

We investigate a micro-fluidic dye laser, which can be integrated with polymer-based lab-on-a-chip microsystems without further processing steps. A simple rate-equation model is used to predict the lasing threshold. The laser device is characterised using the laser dye Rhodamine 6G dissolved...... in ethanol, and the influence of dye concentration on the lasing wavelength and threshold is investigated. The experiments confirm the predictions of the rate-equation model, that lasing can be achieved in the 10 mum long laser cavity with moderate concentrations of Rhodamine 6G in ethanol, starting from 5 x...

Investigation of the lasing of dyes under copper vapor laser irradiation

Energy Technology Data Exchange (ETDEWEB)

Danilova, V I; Kopylova, T N; Maier, G V; Masarnovskii, L V; Soldatov, A N; Sukhanov, V B

1980-10-01

The lasing characteristics of dyes pumped by copper vapor laser radiation are investigated in order to determine the optimal energetic parameters of the dye-laser system. Expressions are derived for the yields of stimulated emission from dye molecules, and it is shown that the most effective means of improving the lasing characteristics of rhodamine dye solutions is by the modification of intermolecular interactions, in part by the use of multicomponent solutions. Results are then presented of experimental measurements of the emission intensities of combinations of rhodamine dyes irradiated by the 5106-A line of a copper vapor laser. An increase in the lasing efficiency of the acceptor molecule is found for all the dye pairs investigated, with even greater emission intensities observed for multicomponent dye mixtures when the mixtures were pumped transversely. Under longitudinal pumping, improvements in lasing efficiency were obtained only for mixtures of rhodamine 6 Zh with cresil violet.

Tunable ultraviolet solid-state dye laser based on MPMMA doped with pyrromethene 597

International Nuclear Information System (INIS)

Jiang, Y G; Fan, R W; Xia, Y Q; Chen, D Y

2011-01-01

Solid-state dye sample based on modified polymethyl methacrylate (MPMMA) co-doped with pyrromethene 597 (PM597), and coumarin 460 (C460) were prepared. A frequency-doubled pulsed Nd:YAG laser is used to pump solid-state dye sample, and the narrow linewidth dye laser of 94.4 mJ was obtained at 582 nm in an oscillator-amplifier configuration. Using a beta-BaB 2 O 4 (BBO) crystal to frequency double the dye laser into ultraviolet (UV), a tuning range from 279 to 305 nm was demonstrated from a single doped PM597 dye. To the best of our knowledge, the UV tuning range is the best under the same condition so far. The conversion slope efficiency from solid dye laser to UV laser was 8.9% and the highest UV laser output energy reached 6.94 mJ at 291 nm

Tunable lasers in isotope separation, a colorful view of a dye chemist

International Nuclear Information System (INIS)

Hammond, P.R.

1976-01-01

Some of the problems to be encountered in the large-scale use of dye lasers in an isotope separation plant are discussed. Why should dye lasers be employed. How can dye conversion efficiency be optimized. How can dye photochemical decomposition and hence running costs be minimized and how serious is this effect anyway. What are toxicity problems with the dye. These and similar issues are examined

Optofluidic third order distributed feedback dye laser

DEFF Research Database (Denmark)

Gersborg-Hansen, Morten; Kristensen, Anders

2006-01-01

which has a refractive index lower than that of the polymer. In combination with a third order DFB grating, formed by the array of nanofluidic channels, this yields a low threshold for lasing. The laser is straightforward to integrate on lab-on-a-chip microsystems where coherent, tunable light......This letter describes the design and operation of a polymer-based third order distributed feedback (DFB) microfluidic dye laser. The device relies on light confinement in a nanostructured polymer film where an array of nanofluidic channels is filled by capillary action with a liquid dye solution...

Photophysical and laser characteristics of pyrromethene 567 dye ...

Indian Academy of Sciences (India)

Narrow-band laser performance of alcohol solutions of pyrromethene 567 ... curves of each dye solution were obtained by scanning the wavelength of the dye ... solutions, using ethanol and methanol solvents, are summarized in table 1.

Control of ring lasers by means of coupled cavities

DEFF Research Database (Denmark)

Buchhave, Preben; Abitan, Haim; Tidemand-Lichtenberg, Peter

2000-01-01

Variable phase coupling to an external ring is used to control a unidirectional ring laser. The observed behavior of the coupled rings is explained theoretically. We have found experimentally that by quickly changing the phase of the feedback from the external ring it is possible to Q......-switch the ring laser. Also, at certain values of the phase of the feedback in the external ring, instabilities in the total system occur and oscillations arise in the ring laser....

Enhancement of polymer dye lasers by multifunctional photonic crystal lattice

DEFF Research Database (Denmark)

Christiansen, Mads Brøkner; Xiao, Sanshui; Mortensen, Asger

2009-01-01

The light output of dye doped hybrid polymer band-edge lasers is increased more than 100 times by using a rectangular lattice photonic crystal, which provides both feedback and couples more pump light into the laser.......The light output of dye doped hybrid polymer band-edge lasers is increased more than 100 times by using a rectangular lattice photonic crystal, which provides both feedback and couples more pump light into the laser....

Single-mode pulsed dye laser pumped by using a diode-pumped Nd:YAG laser with a long pulse width

CERN Document Server

Yi, J H; Moon, H J; Rho, S P; Han, J M; Rhee, Y J; Lee, J M

1999-01-01

The lasing characteristics of a single-mode dye laser pumped by using a diode-pumped solid-state laser (DPSSL) with a high repetition rate is described. A 45-mm-long Nd:YAG rod was pumped by three CW diode arrays and it was acousto-optically Q-switched. A KTP crystal was used for intracavity frequency doubling. The pulse width of the laser ranged from 90 ns to 200 ns, depending on the diode current and the Q-switching frequency. The single-mode dye laser had a grazing incidence configuration. The pulse width of the dye laser was reduced to about 1/8 of the pumping laser pulse width. The effects of the DPSSL Q-switching frequency, the driving current, and the cavity loss on the dye laser pulse width were investigated by using a simple plane-parallel cavity. From the measured pulse width of the dye laser as a function of the reflectivity of the dye laser output coupler, we found that the cavity loss due to the frequency selection elements and the output coupler should be less than 70 % in order to avoid a drast...

Single-mode pulsed dye laser pumped by using a diode-pumped Nd:YAG laser with a long pulse width

International Nuclear Information System (INIS)

Yi, Jong Hoon; Kim, Jin Tae; Moon, Hee Jong; Rho, Si Pyo; Han, Jae Min; Rhee, Yong Joo; Lee, Jong Min

1999-01-01

The lasing characteristics of a single-mode dye laser pumped by using a diode-pumped solid-state laser (DPSSL) with a high repetition rate is described. A 45-mm-long Nd:YAG rod was pumped by three CW diode arrays and it was acousto-optically Q-switched. A KTP crystal was used for intracavity frequency doubling. The pulse width of the laser ranged from 90 ns to 200 ns, depending on the diode current and the Q-switching frequency. The single-mode dye laser had a grazing incidence configuration. The pulse width of the dye laser was reduced to about 1/8 of the pumping laser pulse width. The effects of the DPSSL Q-switching frequency, the driving current, and the cavity loss on the dye laser pulse width were investigated by using a simple plane-parallel cavity. From the measured pulse width of the dye laser as a function of the reflectivity of the dye laser output coupler, we found that the cavity loss due to the frequency selection elements and the output coupler should be less than 70 % in order to avoid a drastically reduced pulse width

Dye-enhanced laser welding for skin closure.

Science.gov (United States)

DeCoste, S D; Farinelli, W; Flotte, T; Anderson, R R

1992-01-01

The use of a laser to weld tissue in combination with a topical photosensitizing dye permits selective delivery of energy to the target tissue. A combination of indocyanine green (IG), absorption peak 780 nm, and the near-infrared (IR) alexandrite laser was studied with albino guinea pig skin. IG was shown to bind to the outer 25 microns of guinea pig dermis and appeared to be bound to collagen. The optical transmittance of full-thickness guinea pig skin in the near IR was 40% indicating that the alexandrite laser should provide adequate tissue penetration. Laser "welding" of skin in vivo was achieved at various concentrations of IG from 0.03 to 3 mg/cc using the alexandrite at 780 nm, 250-microseconds pulse duration, 8 Hz, and a 4-mm spot size. A spectrum of welds was obtained from 1- to 20-W/cm2 average irradiance. Weak welds occurred with no thermal damage obtained at lower irradiances: stronger welds with thermal damage confined to the weld site occurred at higher irradiances. At still higher irradiances, local vaporization occurred with failure to "weld." Thus, there was an optimal range of irradiances for "welding," which varied inversely with dye concentration. Histology confirmed the thermal damage results that were evident clinically. IG dye-enhanced laser welding is possible in skin and with further optimization may have practical application.

Holograms made with a pulsed dye laser

International Nuclear Information System (INIS)

Fernandez-Guasti, M.; Iturbe-Castillo, D.; Silva-Perez, A.; Gil-Villegas, A.; Gonzalez-Torres, H.; Lopez-Guerrero, R.

1989-01-01

We report the obtention of holograms with a nitrogen pumped dye laser, whose source is inherently pulsed. We review the advantages and posibilities of holograms of moving objects which are impossible to make with CW lasers. The lasers used in these experiments were designed and built in the quantum optics laboratory at the Universidad Autonoma Metropolitana-Iztapalapa. (Author)

Diffusion driven optofluidic dye lasers encapsulated into polymer chips

DEFF Research Database (Denmark)

Wienhold, Tobias; Breithaupt, Felix; Vannahme, Christoph

2012-01-01

Lab-on-a-chip systems made of polymers are promising for the integration of active optical elements, enabling e.g. on-chip excitation of fluorescent markers or spectroscopy. In this work we present diffusion operation of tunable optofluidic dye lasers in a polymer foil. We demonstrate that these ......Lab-on-a-chip systems made of polymers are promising for the integration of active optical elements, enabling e.g. on-chip excitation of fluorescent markers or spectroscopy. In this work we present diffusion operation of tunable optofluidic dye lasers in a polymer foil. We demonstrate...... that these first order distributed feedback lasers can be operated for more than 90 min at a pulse repetition rate of 2 Hz without fluidic pumping. Ultra-high output pulse energies of more than 10 μJ and laser thresholds of 2 μJ are achieved for resonator lengths of 3 mm. By introducing comparatively large on......-chip dye solution reservoirs, the required exchange of dye molecules is accomplished solely by diffusion. Polymer chips the size of a microscope cover slip (18 × 18 mm2) were fabricated in batches on a wafer using a commercially available polymer (TOPAS® Cyclic Olefin Copolymer). Thermal imprinting...

50-fs pulse generation directly from a colliding-pulse mode-locked Ti:sapphire laser using an antiresonant ring mirror

Science.gov (United States)

Naganuma, Kazunori; Mogi, Kazuo

1991-05-01

50-fs pulses were directly generated from a colliding-pulse mode-locked Ti:sapphire laser. To achieve the colliding-pulse mode locking, a miniature antiresonant ring containing an organic saturable dye jet was employed as the end mirror for the linear cavity laser. Based on measured dispersion of intracavity elements, a prism pair was implemented to control the cavity dispersion. The generated pulses have no linear chirp but do exhibit parabolic instantaneous frequency owing to third-order dispersion introduced by the prism pair.

Novel Tunable Dye Laser for Lidar Detection, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — A tunable dye laser for Lidar detection will be fabricated based on the innovative dye-doped Holographic Polymer Dispersed Liquid Crystals (HPDLC) technology. The...

Frequency doubled dye laser with a servo-tuned crystal

Energy Technology Data Exchange (ETDEWEB)

Kuhl, J; Spitschan, H

1975-01-01

Spectral tuning of the uv output of a frequency doubled dye laser was successfully controlled by a servo motor system which tilts the nonlinear crystal appropriate for phase-matched second harmonic generation while the dye laser emission wavelength is tuned. The spatial direction of the generated uv beam was used as the regulating signal. The feasibility of this technique for spectroscopic applications was successfully tested.

Dynamics of long ring Raman fiber laser

Science.gov (United States)

Sukhanov, Sergey V.; Melnikov, Leonid A.; Mazhirina, Yulia A.

2016-04-01

The numerical model for dynamics of long fiber ring Raman laser is proposed. The model is based on the transport equations and Courant-Isaacson-Rees numerical method. Different regimes of a long ring fiber Raman laser are investigated.

Study and realisation of a femtosecond dye laser operating at different wavelengths. Ultrashort pulses compression and amplification

International Nuclear Information System (INIS)

Georges, Patrick

1989-01-01

We present the study and the realization of a passively mode-locked dye laser producing pulses shorter than 100 femto-seconds (10 -13 s). In a ring cavity with an amplifier medium (Rhodamine 60) and a saturable absorber (DODCI), a sequence of four prisms controls the group velocity dispersion and allows the generation of very short pulses. Then we have studied the production of femtosecond pulses at other wavelengths directly from the femtosecond dye laser. For the first rime, 60 fs pulses at 685 nm and pulses shorter than 50 fs between 775 nm and 800 nm have been produced by passive mode locking. These near infrared pulses have been used to study the absorption saturation kinetics in semiconductors multiple quantum wells GaAs/GaAlAs. We have observed a singular behavior of the laser operating at 685 nm and analyzed the produced pulses in terms of optical solitons. To perform time resolved spectroscopy with shortest pulses, we have studied a pulse compressor and a multipass amplifier to increase the pulses energy. Pulses of 20 fs and 10 micro-joules (peak power: 0.5 GW) have been obtained at low repetition rate (10 Hz) and pulses of 16 fs and 0.6 micro-joules pulses have been generated at high repetition rate (11 kHz) using a copper vapor laser. These pulses have been used to study the absorption saturation kinetics of an organic dye (the Malachite Green). (author) [fr

PicoGreen dye as an active medium for plastic lasers

Science.gov (United States)

Pradeep, C.; Vallabhan, C. P. G.; Radhakrishnan, P.; Nampoori, V. P. N.

2015-08-01

Deoxyribonucleic acid lipid complex thin films are used as a host material for laser dyes. We tested PicoGreen dye, which is commonly used for the quantification of single and double stranded DNA, for its applicability as lasing medium. PicoGreen dye exhibits enhanced fluorescence on intercalation with DNA. This enormous fluorescence emission is amplified in a planar microcavity to achieve yellow lasing. Here the role of DNA is not only a host medium, but also as a fluorescence dequencher. With the obtained results we have ample reasons to propose PicoGreen dye as a lasing medium, which can lead to the development of DNA based bio-lasers.

Ring cavity surface emitting semiconductor lasers

International Nuclear Information System (INIS)

Mujagic, E.

2010-01-01

Quantum cascade lasers (QCLs) are electrically driven semiconductor lasers, which have undergone a steady improvement since the first demonstration in 1994. These are now well established as reliable sources of coherent light in the mid-infrared (MIR) and terahertz (THz)range of the electromagnetic spectrum (3-300 μm). The rapid progress of this type of lasers is based on a high degree of freedom in tailoring the emission wavelength within a large variety of semiconductor heterostructure designs and materials. These properties have attracted the attention of various applications such as gas analysis, chemical sensing, spectral imaging and free-space telecommunication. In order to improve the selectivity, sensitivity and efficiency of today's sensor systems, high optical power, continuous wave and room temperature performance, single-mode operation and low divergence optical beams, are highly desirable qualities of a compact laser source in this field of research. Since all of these features cannot be provided by a conventional edge-emitting device at the same time, research has put focus on the development of surface emitting devices. Nowadays, the vertical cavity surface emitting lasers (VCSELs) are the most prominent representative for this type of light emitters. With its capability of producing narrow circular beams, the feasibility of two-dimensional arrays and on-wafer testing, such a coherent light source results in a reduction of the fabrication effort and production costs. Since the radiation in QCLs is strictly polarized normal to the epitaxial layer plane, fabrication of VCSELs based on QC structures is not viable. The subject of this work is the design and realization of 'ring cavity surface emitting lasers' (ring-CSELs). This type of lasers employs a circular ring cavity and a resonant distributed feedback (DFB) surface grating. Ring-CSELs were fabricated on the basis of MIR and THz QC structures, which cover a wavelength range from 4 μm to 93 �

Investigation of rf plasma light sources for dye laser excitation

International Nuclear Information System (INIS)

Kendall, J.S.; Jaminet, J.F.

1975-06-01

Analytical and experimental studies were performed to assess the applicability of radio frequency (rf) induction heated plasma light sources for potential excitation of continuous dye lasers. Experimental efforts were directed toward development of a continuous light source having spectral flux and emission characteristics approaching that required for pumping organic dye lasers. Analytical studies were performed to investigate (1) methods of pulsing the light source to obtain higher radiant intensity and (2) methods of integrating the source with a reflective cavity for pumping a dye cell. (TFD)

Monolithic optofluidic ring resonator lasers created by femtosecond laser nanofabrication.

Science.gov (United States)

Chandrahalim, Hengky; Chen, Qiushu; Said, Ali A; Dugan, Mark; Fan, Xudong

2015-05-21

We designed, fabricated, and characterized a monolithically integrated optofluidic ring resonator laser that is mechanically, thermally, and chemically robust. The entire device, including the ring resonator channel and sample delivery microfluidics, was created in a block of fused-silica glass using a 3-dimensional femtosecond laser writing process. The gain medium, composed of Rhodamine 6G (R6G) dissolved in quinoline, was flowed through the ring resonator. Lasing was achieved at a pump threshold of approximately 15 μJ mm(-2). Detailed analysis shows that the Q-factor of the optofluidic ring resonator is 3.3 × 10(4), which is limited by both solvent absorption and scattering loss. In particular, a Q-factor resulting from the scattering loss can be as high as 4.2 × 10(4), suggesting the feasibility of using a femtosecond laser to create high quality optical cavities.

Single longitudinal mode operation of a solid-state dye laser oscillator

CERN Document Server

Lim, G; Kim, H S; Cha, B H; Lee, J M

2000-01-01

We have operated a single longitudinal mode of a solid-state dye laser oscillator in a Littman configuration. The host material of the solid-state gain medium was rhodamine dye-doped poly (methyl methacrylate). The pumping source was the second harmonic of a Nd:YAG laser with a repetition rate of 10 Hz. The measured linewidth of the laser output was about 1.5 GHz.

Amplitude-modulated fiber-ring laser

DEFF Research Database (Denmark)

Caputo, J. G.; Clausen, Carl A. Balslev; Sørensen, Mads Peter

2000-01-01

Soliton pulses generated by a fiber-ring laser are investigated by numerical simulation and perturbation methods. The mathematical modeling is based on the nonlinear Schrödinger equation with perturbative terms. We show that active mode locking with an amplitude modulator leads to a self......-starting of stable solitonic pulses from small random noise, provided the modulation depth is small. The perturbative analysis leads to a nonlinear coupled return map for the amplitude, phase, and position of the soliton pulses circulating in the fiber-ring laser. We established the validity of this approach...

An application of the theory of laser to nitrogen laser pumped dye laser

International Nuclear Information System (INIS)

Osman, Fatima Ahmed

1998-03-01

In this thesis we gave a general discussion on lasers, reviewing some of their properties, types and application. We also conducted an experiment where we obtained a dye laser pumped by nitrogen laser with a wave length of 337.1 nm and a power of 5 Mw.It was noticed that the produced radiation possesses characteristics different from those of other types of laser. This characteristics determine the tunability i.e the possibility of choosing the appropriately required wave-length of radiation for various applications.(Author)

Identification Of Natural Dyes On Archaeological Textile Objects Using Laser Induced Fluorescent Technique

International Nuclear Information System (INIS)

Abdel-Kareem, O.; Eltokhy, A.; Harith, M. A.

2011-01-01

This study aims to evaluate the use of Laser Fluorescent as a non-destructive technique for identification of natural dyes on archaeological textile objects. In this study wool textile samples were dyed with 10 natural dyes such as cochineal, cutch, henna, indigo, Lac, madder, safflower, saffron, sumac and turmeric. These dyes common present on archaeological textile objects to be used as standard dyed textile samples. These selected natural dyes will be used as known references that can be used a guide to identify unknown archaeological dyes. The dyed textile samples were investigated with laser radiation in different wavelengths to detect the best wavelengths for identification each dye. This study confirms that Laser Florescent is very useful and a rapid technique can be used as a non-destructive technique for identification of natural dyes on archaeological textile objects. The results obtained with this study can be a guide for all conservators in identification of natural organic dyes on archaeological textile objects.

Identification Of Natural Dyes On Archaeological Textile Objects Using Laser Induced Fluorescent Technique

Science.gov (United States)

Abdel-Kareem, O.; Eltokhy, A.; Harith, M. A.

2011-09-01

This study aims to evaluate the use of Laser Fluorescent as a non-destructive technique for identification of natural dyes on archaeological textile objects. In this study wool textile samples were dyed with 10 natural dyes such as cochineal, cutch, henna, indigo, Lac, madder, safflower, saffron, sumac and turmeric. These dyes common present on archaeological textile objects to be used as standard dyed textile samples. These selected natural dyes will be used as known references that can be used a guide to identify unknown archaeological dyes. The dyed textile samples were investigated with laser radiation in different wavelengths to detect the best wavelengths for identification each dye. This study confirms that Laser Florescent is very useful and a rapid technique can be used as a non-destructive technique for identification of natural dyes on archaeological textile objects. The results obtained with this study can be a guide for all conservators in identification of natural organic dyes on archaeological textile objects.

Development of tunable flashlamp excited dye laser system

International Nuclear Information System (INIS)

Bhanthumnavin, V.; Apikitmata, S.; Kochareon, P.

1991-01-01

A tunable flashlamp excited dye laser (FEDL) was successfully developed for the first time in Thailand by Thai scientists at KMIT Thonburi (Bangmod). The Rhodamine 6G dissolved in ethyl alcohol was utilized as a laser medium and circulated by a pump through a laser head. The dye cuvette had an inner diameter of 4.0 mm and was 90 mm long. The cavity mirrors M 1 , and M 2 were concave mirrors with reflectivities of 100% and 73% respectively. A power supply of 0-20 kV and current of 0-50 mA charged a capacitor of 0.3 μ f at 10-15 kV which was then discharged via a spark gap through the flashlamp. The output laser wavelengths was tunable from λ = 550-640 nm. It is the first FEDL system, locally developed, which has a tunable wavelength for the laser output. The laser pulse width is about 1.0 μs with energy of 20 mJ and peak power pf 20 KW. The repetition rate of the laser is 1/15 Hz. (author). 14 refs, 7 figs

Bibliographic study of photophysical and photochemical properties of laser dyes

International Nuclear Information System (INIS)

Doizi, D.

1986-06-01

Laser isotope separation of uranium requires high power and precise wave length. This report is a bibliographic and experimental study of the photophysical and photochemical properties of seven commercial laser dyes which have an emission wavelength in the range 5500-6500 A: Rhodamine 110 or 560, rhodamine 6G or 590, rhodamine B or 610, rhodamine 101 or 640, sulforhodamine B or kiton red 620, sulforhodamine 101 or 640 and DCM or LC 6500. Absorption and emission cross section values, fluorescence lifetimes and quantum yields in various solvents are indicated. For each dye, a non exhaustive list of laboratory experiments made with two types of pump sources: Nd YAG (532) and copper vapor laser is given. When it is known, the toxicity of the dyes is mentioned [fr

Measuring of nonlinearity of dye doped liquid crystals using of self phase modulation effect

International Nuclear Information System (INIS)

Abedi, M.; Jafari, A.; Tajalli, H.

2007-01-01

Self phase modulation in dye doped liquid crystals has investigated and the nonlinearity of dye doped liquid crystals is measured by this effect. The Self phase modulation effect can be used for producing optical micro rings that have many applications in photonics and laser industries.

Studies on widely tunable ultra-short laser pulses using energy transfer distributed feedback dye laser

International Nuclear Information System (INIS)

Ahamed, M.B.; Ramalingam, A.; Palanisamy, P.K.

2003-01-01

This paper presents both theoretical and experimental study of the characteristics of Nd: YAG laser pumped energy transfer distributed feedback dye laser (ETDFDL). Using theoretical model proposed, the behavior of ETDFDL such as the characteristics of donor DFDL, the acceptor DFDL, the dependence of their pulse width and output power on donor-acceptor concentrations and pump power are studied for dye mixture Rhodamine 6G and Cresyl Violet in detail. Experimentally using prism-dye cell configuration, the ETDFDL output is obtained and the output energy of DFDL is measured at the emission peaks of donor and acceptor dyes for different pump powers and donor-acceptor concentrations. In addition, the DFDL linewidth measurement has been carried out at the lasing wavelengths of the donor and acceptor dyes using Fabry-Perot etalon and the tunability of DFDL is measured to be in the wavelength range of 545-680 nm

Dye-enhanced diode laser photocoagulation of choroidal neovascularizations

Science.gov (United States)

Klingbeil, Ulrich; Puliafito, Carmen A.; McCarthy, Dan; Reichel, Elias; Olk, Joseph; Lesiecki, Michael L.

1994-06-01

Dye-enhanced diode laser photocoagulation, using the dye indocyanine green (ICG), has shown some potential in the treatment of choroidal neovascularizations (CNV). A diode laser system was developed and optimized to emit at the absorption maximum of ICG. In a clinical study at two retinal centers, more than 70 patients, the majority of which had age-related macular degeneration, were treated. Eighteen cases with ill-defined subfoveal CNV were followed an average of 11 months after laser treatment. The results show success in resolving the CNV with an average long-term preservation of visual function equal to or superior to data provided by the Macular Photocoagulation Study for confluent burns of low intensity applied to the CNV. Details of the technique and discussion of the controversies inherent in such a treatment strategy will be presented.

Ultraviolet-pumped liquid-crystal dye-laser

International Nuclear Information System (INIS)

Bertolotti, M.; Sbrolli, L.; Scudieri, F.; Papa, T.

1981-01-01

The possibility offered by the orientation properties of liquid crystals as a matrix for dye lasers is shown. In particular, the linear polarization of emitted light can be changed by acting with an external magnetic field on the molecular nematic director. (author)

In liquid laser treated graphene oxide for dye removal

Energy Technology Data Exchange (ETDEWEB)

Russo, Paola, E-mail: rsspla1@gmail.com [Dipartimento di Scienze Chimiche, Universita’ degli Studi di Catania, Viale Andrea Doria 6, Catania 95125 (Italy); Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Ave., West Waterloo, Ontario N2L 3G1 (Canada); D’Urso, Luisa [Dipartimento di Scienze Chimiche, Universita’ degli Studi di Catania, Viale Andrea Doria 6, Catania 95125 (Italy); Hu, Anming [Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, TN 57996-2210 (United States); Zhou, Norman [Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Ave., West Waterloo, Ontario N2L 3G1 (Canada); Compagnini, Giuseppe [Dipartimento di Scienze Chimiche, Universita’ degli Studi di Catania, Viale Andrea Doria 6, Catania 95125 (Italy)

2015-09-01

Highlights: • Graphene oxide and reduced graphene oxide were tested as adsorbents for dye removal from water. • Reduced graphene oxide was obtained after laser irradiation of a colloidal suspension of graphene oxide. • Methylene blue was chosen as the dye to test graphene oxide and reduced graphene oxide. - Abstract: The presence of dyes, pharmaceuticals and many other pollutants in wastewaters is critical due to severe effects on the human beings and on the environment. Here, solutions of graphene oxide (GO) and reduced graphene oxide (rGO) were tested as adsorbents for the removal of methylene blue (MB), a cationic dye, from aqueous media. The reduced forms of graphene oxide were obtained after laser irradiation of colloidal suspensions of graphene oxide, obtained by the Hummers and Offeman's method. We observed that both graphene oxide and its reduced forms are excellent adsorbents towards methylene blue. In particular, rGO showed a higher adsorption capacity than GO, suggesting that a strict control of laser irradiation time permits to obtain rGO with different degrees of reduction and therefore the residual oxygenated functional groups may influence the adsorption behaviour more or less. Characterization of the samples by atomic force microscopy (AFM) showed that produced rGO sheets via laser irradiation exhibited a discontinuous surface where some holes could be detected contributing to an enhancement of the rGO surface area that is a higher adsorption capacity.

Tunable lasers in isotope separation: a colorful view of a dye chemist

International Nuclear Information System (INIS)

Hammond, P.R.

1977-01-01

Some of the problems to be encountered in the possible large scale use of dye lasers in an isotope separation plant are discussed.The effect of laser dye deterioration on performance is examined algebraically in terms of disappearance of dye molecules and the appearance of a new, single chemical product having absorption in the fluorescence band for a single pass through a transversely pumped amplifier. Loss of output, defined as ''quantum yield of laser deterioration'', Q/sub L/, is related to the true quantum yield of molecular destruction of the dye Q/sub M/, and other known parameters. 6-Diethylamino 3-keto fluoran, an example of an oxygen tricyclic merocyanine, is described. It was first reported in the pre-1900 German literature under the name of Chromogen Red B and it is an ineffective lasing dye on account of low fluorescence quantum yield. The techniques for measurement and the excited state absorption cross-sections are reported for the dyes rhodamine 6G fluoroborate in alcohol, rhodamine B basic solution in trifluoroethanol and kiton red S in trifluoroethanol

Surface emitting ring quantum cascade lasers for chemical sensing

Science.gov (United States)

Szedlak, Rolf; Hayden, Jakob; Martín-Mateos, Pedro; Holzbauer, Martin; Harrer, Andreas; Schwarz, Benedikt; Hinkov, Borislav; MacFarland, Donald; Zederbauer, Tobias; Detz, Hermann; Andrews, Aaron Maxwell; Schrenk, Werner; Acedo, Pablo; Lendl, Bernhard; Strasser, Gottfried

2018-01-01

We review recent advances in chemical sensing applications based on surface emitting ring quantum cascade lasers (QCLs). Such lasers can be implemented in monolithically integrated on-chip laser/detector devices forming compact gas sensors, which are based on direct absorption spectroscopy according to the Beer-Lambert law. Furthermore, we present experimental results on radio frequency modulation up to 150 MHz of surface emitting ring QCLs. This technique provides detailed insight into the modulation characteristics of such lasers. The gained knowledge facilitates the utilization of ring QCLs in combination with spectroscopic techniques, such as heterodyne phase-sensitive dispersion spectroscopy for gas detection and analysis.

Solvent effects on lasing characteristics for Rh B laser dye

Energy Technology Data Exchange (ETDEWEB)

Peter, Jaison, E-mail: jaison.peter@gmail.com [International School of Photonics, Cochin University of Science and Technology, Cochin 682022 (India); Kumar, Mahesh [Department of Applied Chemistry, Cochin University of Science and Technology, Cochin 682022 (India); Ananad, V.R.; Saleem, Rasool; Sebastian, Ananthu; Radhakrishnan, P.; Nampoori, V.P.N.; Vallabhan, C.P.G. [International School of Photonics, Cochin University of Science and Technology, Cochin 682022 (India); Prabhu, Radhakrishna [School of Engineering, Robert Gordon University, Aberdeen AB10 1FR, Scotland (United Kingdom); Kailasnath, M. [International School of Photonics, Cochin University of Science and Technology, Cochin 682022 (India)

2016-01-15

We demonstrate pulsed, photopumped multimode laser emission in the visible spectral range from rhodamine B dye dissolved in various solvents. The laser emission is characterized by a well-defined, low threshold pump power at which the emission spectral intensity dramatically increases and collapsed into several dominant laser modes with reduced mode spacing and spectral width. The modes were found to originate from the subcavities formed by the plane-parallel walls of the cuvette containing the gain medium. The cavity lasing spectral structure and the numbers of longitudinal modes were easily controlled by changing the solvents. A shift in the emission spectra has been also observed by changing the solvents will allow a limited range of tuning of laser emission wavelength. We also determined the gain coefficient and stimulated emission cross-section for the Rh B dye dissolved liquid laser system. A detailed discussion of the solvent effect in the lasing characteristics of Rh B in different solution is explained along with the computational data. - Highlights: • Report multimode laser emission from rhodamine B dye dissolved in various solvents. • Modes are originated from the plane-parallel walls of the cuvette. • Spectral range and the number of modes can be controlled by changing the solvents. • Changing solvents also allows a limited range of tuning of laser emission.

Ring laser frequency biasing mechanism

International Nuclear Information System (INIS)

McClure, R.E.

1975-01-01

A ring laser cavity including a magnetically saturable member for differentially phase shifting the contradirectional waves propagating in the laser cavity, the phase shift being produced by the magneto-optic interaction occurring between the light waves and the magnetization in the cavity forming component as the light waves are reflected therefrom is described

Analysis of photoisomerizable dyes using laser absorption and fluorescence techniques

International Nuclear Information System (INIS)

Duchowicz, R.; Di Paolo, R.E.; Scaffardi, L.; Tocho, J.O.

1992-01-01

The attention of the present report has been directed mainly to the description of laser-based techniques developed in order to obtain kinetic and spectroscopic properties of polymethine cyanine dyes in solution. Special attention was dedicated to photoisomerizable molecules where the absorption spectra of both isomers are strongly overlapped. As an example, measurements of two different dyes of laser technological interest, DTCI and DODCI were performed. The developed methods provide a complete quantitative description of photophysical processes. (author). 14 refs, 6 figs

Laser plasma focus produced in a ring target

International Nuclear Information System (INIS)

Saint-Hilaire, G.; Szili, Z.

1976-01-01

A new geometry for generating a laser-produced plasma is presented. A toroidal mirror is used to focus a CO 2 laser beam on the inside wall of a copper ring target. The plasma produced converges at the center of the ring where an axial plasma focus is formed. High-speed photography shows details of a plasma generated at a distance from the target surface. This new geometry could have important applications in the field of x-ray lasers

Tunable dye laser research at U. N. E

Energy Technology Data Exchange (ETDEWEB)

Haydon, S C

1976-10-01

Attempts to extend present tunable radiation sources into the wavelength region from 140 to 330 nm are presented in the following areas: frequency doubling and parametric upconversion methods, frequency mixing techniques in metal vapors, the pulsed N/sub 2/ laser, tunable dye lasers for the near uv to ir spectral range, heat pipe ovens, and preliminary experiments. (MHR)

Electrospun dye-doped fiber networks: lasing emission from randomly distributed cavities

DEFF Research Database (Denmark)

Krammer, Sarah; Vannahme, Christoph; Smith, Cameron

2015-01-01

Dye-doped polymer fiber networks fabricated with electrospinning exhibit comb-like laser emission. We identify randomly distributed ring resonators being responsible for lasing emission by making use of spatially resolved spectroscopy. Numerical simulations confirm this result quantitatively....

Lasing of Some Red Laser Dyes in Annealed Silica Xerogel

Science.gov (United States)

Bezkrovnaya, O. N.; Maslov, V. V.; Pritula, I. M.; Yurkevich, A. G.

2018-01-01

The spectral and energy characteristics of generation in the red spectral region 650-720 nm were measured and analyzed for three laser dyes in preliminarily annealed SiO2 xerogel matrices under laser excitation λp = 588 nm in a nonselective cavity. The specific laser-energy output for two of them (LK678 and Ox170) in the matrices was 10-13% higher than in MeOH. NBA dye in the matrix generated two laser radiation bands in the 700-720 nm region with pumping E p ≥ 80 mJ whereas its generation threshold in MeOH exceeded the maximum pumping energy of 140 mJ so that NBA generation was not observed. Laser emission spectra of the studied matrices in a nonselective cavity were red-shifted by 1000 cm-1 from the fluorescence maximum. Such a shift could improve the characteristics of biosensors based on these matrices.

Development of the plastic solid-dye cell for tunable solid-state dye lasers and study on its optical properties

Energy Technology Data Exchange (ETDEWEB)

Ko, Do Kyeong; Lee, Jong Min; Cha, Byung Heon; Yi, Jong Hoon; Lee, Kang Soo; Kim, Sung Ho; Lim, Gwon

2000-01-01

We have fabricated solid-state dyes with Copolex NK-55, which is the base element of plastic lens, and PMMA. We have measured the longevity of solid-state dyes doped in both polymers and found that PMMA has better properties than Coploex NK-55. We have realized the tuning range of 560-620 nm by doping rhodamine 6Gand rhodamin B in the manufactured solid-state dye laser oscillators. In the standing-wave cavity we achieved the slop efficiency of 10.8 percent and in the grazing incidence cavity, 1.2 percent. We have constructed a very compact grazing- incidence cavity which is only 6 cm long and the linewidth of the laser was less than 1.5 GHz with 3-ns pulse duration. And we have fabricated disk-type solid-state dye cell and installed it in the cavity in which the dye cell can be translated and rotated with the help of the two steeping motors. By this we could constantly changed the illuminated area of the dye cell and , therefore, were able to achieve long time operation and to use almost the entire region of the solid-state dye cell. (author)

Development of the plastic solid-dye cell for tunable solid-state dye lasers and study on its optical properties

International Nuclear Information System (INIS)

Ko, Do Kyeong; Lee, Jong Min; Cha, Byung Heon; Yi, Jong Hoon; Lee, Kang Soo; Kim, Sung Ho; Lim, Gwon

2000-01-01

We have fabricated solid-state dyes with Copolex NK-55, which is the base element of plastic lens, and PMMA. We have measured the longevity of solid-state dyes doped in both polymers and found that PMMA has better properties than Coploex NK-55. We have realized the tuning range of 560-620 nm by doping rhodamine 6G and rhodamin B in the manufactured solid-state dye laser oscillators. In the standing-wave cavity we achieved the slop efficiency of 10.8 percent and in the grazing incidence cavity, 1.2 percent. We have constructed a very compact grazing- incidence cavity which is only 6 cm long and the linewidth of the laser was less than 1.5 GHz with 3-ns pulse duration. And we have fabricated disk-type solid-state dye cell and installed it in the cavity in which the dye cell can be translated and rotated with the help of the two steeping motors. By this we could constantly changed the illuminated area of the dye cell and , therefore, were able to achieve long time operation and to use almost the entire region of the solid-state dye cell. (author)

Measurement of liquid sheet using laser tagging method by photochromic dye

Science.gov (United States)

Rosli, Nurrina Binti; Amagai, Kenji

2014-12-01

Liquid atomization system has been extensively applied as the most significant process in many industrial fields. In the internal combustion engine, the combustion phenomenon is strongly influenced by the spray characteristics of the fuel given by the atomization process. In order to completely understand the whole atomization process, a detail investigation of relations between the liquid jet characteristics and the breakup phenomenon is required. In this study, a non-intrusive method called as laser tagging method by photochromic dye has been developed with aim to study the breakup process of liquid sheet in detail, covering from the behavior in film until disintegrated into ligament and droplets. The laser tagging method by photochromic dye is based on a shift in the absorption spectrum of photochromic dye molecules tagged by ultraviolet laser. The shift results a color change at the tagged region of liquid containing the dye. In this study, the motions of the dye traces were analyzed as the liquid surface velocity. As a result, liquid sheet was found to keep its velocity constantly in film before suddenly increase around broken point. However, it then decreased after broken into droplets. By forming a set of four points of dye traces on the liquid sheet, the change of relative position of the set enabled the measurement of deformation and rotational motion of the liquid sheet. As a result, the normal strain of the liquid sheet parallel to the flow direction depended on the flow behavior of ligament formation.

Solid-state ring laser gyroscope

Science.gov (United States)

Schwartz, S.

The ring laser gyroscope is a rotation sensor used in most kinds of inertial navigation units. It usually consists in a ring cavity filled with a mixture of helium and neon, together with high-voltage pumping electrodes. The use of a gaseous gain medium, while resulting naturally in a stable bidirectional regime enabling rotation sensing, is however the main industrially limiting factor for the ring laser gyroscopes in terms of cost, reliability and lifetime. We study in this book the possibility of substituting for the gaseous gain medium a solid-state medium (diode-pumped Nd-YAG). For this, a theoretical and experimental overview of the lasing regimes of the solid-state ring laser is reported. We show that the bidirectional emission can be obtained thanks to a feedback loop acting on the states of polarization and inducing differential losses proportional to the difference of intensity between the counterpropagating modes. This leads to the achievement of a solid-state ring laser gyroscope, whose frequency response is modified by mode coupling effects. Several configurations, either mechanically or optically based, are then successively studied, with a view to improving the quality of this frequency response. In particular, vibration of the gain crystal along the longitudinal axis appears to be a very promising technique for reaching high inertial performances with a solid-state ring laser gyroscope. Gyrolaser à état solide. Le gyrolaser est un capteur de rotation utilisé dans la plupart des centrales de navigation inertielle. Dans sa forme usuelle, il est constitué d'une cavité laser en anneau remplie d'un mélange d'hélium et de néon pompé par des électrodes à haute tension. L'utilisation d'un milieu amplificateur gazeux, si elle permet de garantir naturellement le fonctionnement bidirectionnel stable nécessaire à la mesure des rotations, constitue en revanche la principale limitation industrielle des gyrolasers actuels en termes de coût, fiabilit

Femtosecond laser-induced concentric ring microstructures on Zr-based metallic glass

International Nuclear Information System (INIS)

Ma Fengxu; Yang Jianjun; Xiaonong Zhu; Liang Chunyong; Wang Hongshui

2010-01-01

Surface morphological evolution of Zr-based metallic glass ablated by femtosecond lasers is investigated in atmosphere condition. Three types of permanent ring structures with micro-level spacing are observed for different laser shots and fluences. In the case of low laser fluences, the generation of annular patterns with nonthermal features is observed on the rippled structure with the subwavelength scale, and the ring spacing shows a decrease tendency from the center to the margin. While in the case of high laser fluences, the concentric rings formation within the laser spot is found to have evident molten traces and display the increasing ring spacing along the radial direction. Moreover, when the laser shots accumulation becomes large, the above two types of ring microstructures begin to develop into the common ablation craters. Analysis and discussion suggests that the stress-induced condensation of ablation vapors and the frozen thermocapillary waves on the molten surfaces should be responsible for the formation of two different types of concentric ring structures, respectively. Eventually, a processing window for each resulting surface microstructure type is obtained experimentally and indicates the possibility to control the morphological transitions among different types.

Polymer photonic crystal dye lasers as label free evanescent cell sensors

DEFF Research Database (Denmark)

Christiansen, Mads Brøkner; Lopacinska, Joanna M.; Jakobsen, Mogens Havsteen

2009-01-01

. The lasers are fabricated by combined nanoimprint and photolithography (CNP) in Ormocore hybrid polymer doped with the laser dye Pyrromethene 597. The lasers emit in the chip plane at a wavelength around 595 nm when pumped with 5 ns pulses from a compact frequency doubled Nd:YAG laser. We investigate...

Semiconductor ring lasers coupled by a single waveguide

Science.gov (United States)

Coomans, W.; Gelens, L.; Van der Sande, G.; Mezosi, G.; Sorel, M.; Danckaert, J.; Verschaffelt, G.

2012-06-01

We experimentally and theoretically study the characteristics of semiconductor ring lasers bidirectionally coupled by a single bus waveguide. This configuration has, e.g., been suggested for use as an optical memory and as an optical neural network motif. The main results are that the coupling can destabilize the state in which both rings lase in the same direction, and it brings to life a state with equal powers at both outputs. These are both undesirable for optical memory operation. Although the coupling between the rings is bidirectional, the destabilization occurs due to behavior similar to an optically injected laser system.

Ring lasers - a brief history

Science.gov (United States)

Klein, Tony

2017-10-01

Used these days in inertial navigation, ring lasers are also used in recording the tiniest variations in the Earth's spin, as well in detecting earthquakes and even the drift of continents. How did it all begin?

Progress in solid state dye laser development

Energy Technology Data Exchange (ETDEWEB)

Hermes, R.E.

1990-01-01

A triaxial flashlamp (15 cm) was used to optically pump laser rods prepared from an acrylate based copolymer (0.95 cm O.D. {times} 10.0 cm L.). The performance of 13 laser dyes incorporated into this polymeric solid host is reported. The best lasing performance was obtained with sulforhodamine-B, with a calculated slope efficiency of 0.52% and a maximum single pulse output energy of 580 mJ. A commercially available fluorescent polymeric material was also evaluated. 12 refs., 2 figs.

Laser incising of wood: Impregnation of columns with water-soluble dye

International Nuclear Information System (INIS)

Hattori, N.; Ando, K.; Kitayama, S.; Nakamura, Y.

1994-01-01

To know whether or not laser incising is a useful pre-treatment technique in impregnating a chemical fluid into lumber, pin holes were made in columns of hinoki (Chamaecyparis obtusa Endl.), sugi (Cryptomeria japonica D. Don), karamatsu (Larix leptolepis Gordon) and douglas-fir (Pseudo-tsuga menziesii Franco) with 1.7 kW CO2 laser, and a water-soluble dye was impregnated into these columns with a local pressure impregnation device. Retentions, and lengths and widths of penetrations from each hole were measured quantitatively. Referring to the results of the preparatory experiment mentioned above, incising patterns for sugi and douglas-fir were designed, and the same water-soluble dye was impregnated into the laser-incised columns as well as into non-incised ones with the vacuum-pressure method to obtain penetrated layers with the target depths completely. As a result, a retention of 200 kg/m3 of dye could be achieved for a column of douglas-fir even if it is a species difficult to impregnate. The penetrated layer also could be formed completely at the depth of the laser incision. Therefore, it is concluded that laser incising can be used for the pre-treatment before impregnation of wood columns. (author)

Single-mode solid-state polymer dye laser fabricated with standard I-line UV lithography

DEFF Research Database (Denmark)

Balslev, Søren; Mironov, Andrej; Nilsson, Daniel

2005-01-01

We present single-mode solid-state polymer dye lasers fabricated with standard UV lithography. The lasers use a high-order Bragg grating and rely on index-tuning of a photosensitive polymer for waveguiding. The gain medium is Rhodamine 6G.......We present single-mode solid-state polymer dye lasers fabricated with standard UV lithography. The lasers use a high-order Bragg grating and rely on index-tuning of a photosensitive polymer for waveguiding. The gain medium is Rhodamine 6G....

Optimal control of quantum rings by terahertz laser pulses.

Science.gov (United States)

Räsänen, E; Castro, A; Werschnik, J; Rubio, A; Gross, E K U

2007-04-13

Complete control of single-electron states in a two-dimensional semiconductor quantum-ring model is established, opening a path into coherent laser-driven single-gate qubits. The control scheme is developed in the framework of optimal-control theory for laser pulses of two-component polarization. In terms of pulse lengths and target-state occupations, the scheme is shown to be superior to conventional control methods that exploit Rabi oscillations generated by uniform circularly polarized pulses. Current-carrying states in a quantum ring can be used to manipulate a two-level subsystem at the ring center. Combining our results, we propose a realistic approach to construct a laser-driven single-gate qubit that has switching times in the terahertz regime.

Molecular reorientation of dye doped nematic liquid crystals in the laser illumination

International Nuclear Information System (INIS)

San, S. E.; Koeysal, O.; Ecevit, F. N.

2002-01-01

In this study it is investigated how dye doped nematic liquid crystals reorient under the illumination of laser beam whose wavelength is appropriate to absorbance characteristics of the doping dye. Nematic liquid crystal E7 is used with anthraquinone dye 1% wt/wt in the preparation of the sample and this material is filled in homegenously aligned measurement cell having 15 μm thickness. Mechanism of molecular reorientation includes the absorbance effects of the energy of laser by doping dye and this reorientation causes the refractive index of the material to be changed. There are potential application possibilities of such molecular reorientation based effects in nonlinear optics such as real time holography whose basis is grating diffraction that is observed and investigated in the frame of fundamentals of molecule light interaction mechanisms. Experimental analyses allowed finding characteristic values of diffraction signals depending on physical parameters of set up for a dye doped liquid crystal system and this system provided a 20 % diffraction efficiency under the optimum circumstances

Single mode dye-doped polymer photonic crystal lasers

DEFF Research Database (Denmark)

Christiansen, Mads Brøkner; Buss, Thomas; Smith, Cameron

2010-01-01

Dye-doped polymer photonic crystal (PhC) lasers fabricated by combined nanoimprint and photolithography are studied for their reproducibility and stability characteristics. We introduce a phase shift in the PhC lattice that substantially improves the yield of single wavelength emission. Single mode...... emission and reproducibility of laser characteristics are important if the lasers are to be mass produced in, e. g., optofluidic sensor chips. The fabrication yield is above 85% with highly reproducible wavelengths (within 0.5%), and the temperature dependence on the wavelength is found to be -0.045 or -0...

The use of laser diodes for control of uranium vaporization rates

International Nuclear Information System (INIS)

Hagans, K.; Galkowski, J.

1993-09-01

Within the Atomic Vapor Laser Isotope Separation (AVLIS) program we have successfully used the laser absorption spectroscopy technique (LAS) to diagnose process physics performance and control vaporization rate. In the LAS technique, a narrow line-width laser is tuned to an absorption line of the species to be measured. The laser light that is propagated through the sample is and, from this data, the density of the species can be calculated. These laser systems have exclusively consisted of expensive, cumbersome, and difficult to maintain argon-ion-pumped ring dye lasers. While the wavelength flexibility of dye lasers is very useful in a laboratory environment, these laser systems are not well suited for the industrial process control system under development for an AVLIS plant. Diode-lasers offer lower system costs, reduced man power requirements, reduced space requirements, higher system availability, and improved operator safety. We report the. successful deployment and test of a prototype laser diode based uranium vapor rate control system. Diode-laser generated LAS data was used to control the uranium vaporization rate in a hands-off mode for greater than 50 hours. With one minor adjustment the system successfully controlled the vaporization rate for greater than 147 hours. We report excellent agreement with ring dye laser diagnostics and uranium weigh-back measurements

Dye laser light for high-resolution classical photography

International Nuclear Information System (INIS)

Geissler, K.K.

1982-01-01

The test run with the bubble chamber HOLEBC in October 1981 offered the opportunity of checking the usefulness of de-speckled dye laser light for illumination purposes in high-resolution classical dark field photography of small bubble chambers. (orig./HSI)

Treatment of inflammatory facial acne vulgaris with combination 595-nm pulsed-dye laser with dynamic-cooling-device and 1,450-nm diode laser.

Science.gov (United States)

Glaich, Adrienne S; Friedman, Paul M; Jih, Ming H; Goldberg, Leonard H

2006-03-01

The 585-nm pulsed-dye laser and the 1,450-nm diode laser have been found effective for the treatment of mild-to-moderate inflammatory facial acne. This study was designed to evaluate the efficacy and safety of the combined treatment with the 595-nm pulsed-dye laser and the 1,450-nm diode laser for inflammatory facial acne. Fifteen patients with inflammatory facial acne were treated with a combination of the 595-nm pulsed-dye laser and the 1,450-nm diode laser. Patients' subjective response to treatment was evaluated regarding improvement in acne, acne scarring, oiliness, and redness of the skin. All patients had reductions in acne lesion counts. Mean lesion counts decreased 52% (P < 0.01), 63% (P < 0.01), and 84% (P < 0.01) after one, two, and three treatments, respectively. Patients described moderate-to-marked improvement in acne, acne scarring, and post-inflammatory erythema. Adverse effects were limited to mild, transient erythema. The combination of the 595-nm pulsed-dye laser and the 1,450-nm diode laser is safe and effective for the treatment of inflammatory facial acne, acne scarring, and post-inflammatory erythema. 2005 Wiley-Liss, Inc.

Coffee-ring effects in laser desorption/ionization mass spectrometry.

Science.gov (United States)

Hu, Jie-Bi; Chen, Yu-Chie; Urban, Pawel L

2013-03-05

This report focuses on the heterogeneous distribution of small molecules (e.g. metabolites) within dry deposits of suspensions and solutions of inorganic and organic compounds with implications for chemical analysis of small molecules by laser desorption/ionization (LDI) mass spectrometry (MS). Taking advantage of the imaging capabilities of a modern mass spectrometer, we have investigated the occurrence of "coffee rings" in matrix-assisted laser desorption/ionization (MALDI) and surface-assisted laser desorption/ionization (SALDI) sample spots. It is seen that the "coffee-ring effect" in MALDI/SALDI samples can be both beneficial and disadvantageous. For example, formation of the coffee rings gives rise to heterogeneous distribution of analytes and matrices, thus compromising analytical performance and reproducibility of the mass spectrometric analysis. On the other hand, the coffee-ring effect can also be advantageous because it enables partial separation of analytes from some of the interfering molecules present in the sample. We report a "hidden coffee-ring effect" where under certain conditions the sample/matrix deposit appears relatively homogeneous when inspected by optical microscopy. Even in such cases, hidden coffee rings can still be found by implementing the MALDI-MS imaging technique. We have also found that to some extent, the coffee-ring effect can be suppressed during SALDI sample preparation. Copyright © 2013 Elsevier B.V. All rights reserved.

Evidence for laser emission from the TICT exciplex of coumarin dyes

International Nuclear Information System (INIS)

Masilamani, V.

1987-06-01

This paper gives confirming evidence for the possibility of super radiant laser emission from the Twisted Internal Charge Transfer (TICT) conformation in exicted state complexation with the solvent, of coumarin family of laser dyes. (author). 6 refs, 1 fig., 2 tabs

Single mode dye-doped polymer photonic crystal lasers

International Nuclear Information System (INIS)

Christiansen, Mads B; Buß, Thomas; Smith, Cameron L C; Petersen, Sidsel R; Jørgensen, Mette M; Kristensen, Anders

2010-01-01

Dye-doped polymer photonic crystal (PhC) lasers fabricated by combined nanoimprint and photolithography are studied for their reproducibility and stability characteristics. We introduce a phase shift in the PhC lattice that substantially improves the yield of single wavelength emission. Single mode emission and reproducibility of laser characteristics are important if the lasers are to be mass produced in, e.g., optofluidic sensor chips. The fabrication yield is above 85% with highly reproducible wavelengths (within 0.5%), and the temperature dependence on the wavelength is found to be −0.045 or −0.066 nm K -1 , depending on the material

Development of high-power laser technology. Fabrication of a dye cell of the high power dye laser and development of the measurement technology of the fluid velocities in a dye cell

Energy Technology Data Exchange (ETDEWEB)

Jo, Jae Heung; Chang, Soo; Lim, Kwon; Kim, Jee Teak; Choi, Wan Hae [Hannam University, Taejon (Korea, Republic of)

1995-08-01

The computer simulation code for the simulation of the steady-state flow in a dye cell is developed by using the finite element method. The situation of the fluid flow is measured by the diode laser LDV system and compared with results of the computer simulation. The small size Fiber-Optic LDV with a directional coupler is designed and fabricated for the real time measurement of fluid velocities in a dye cell. (author). 13 refs.

CW organic dye laser

International Nuclear Information System (INIS)

Tuccio, S.A.; Peterson, O.G.

1975-01-01

A method and apparatus for producing continuous emission from a lasing medium comprising organic dye molecules in solution are described. Continuous emission is accomplished by flowing the medium through a focused optical cavity while simultaneously producing a population inversion in that portion of the medium flowing in close proximity to the focal point of the cavity. The population inversion is produced by pumping the medium longitudinally, along the optical axis of the cavity, preferably by the focused output of a continuous-wave argon laser. Sufficient thermal energy is continuously dissipated from the medium to maintain the optical homogeneity thereof at or above the quality required for continuous emission

Optimization of the geometrical stability in square ring laser gyroscopes

International Nuclear Information System (INIS)

Santagata, R; Beghi, A; Cuccato, D; Belfi, J; Beverini, N; Virgilio, A Di; Ortolan, A; Porzio, A; Solimeno, S

2015-01-01

Ultra-sensitive ring laser gyroscopes are regarded as potential detectors of the general relativistic frame-dragging effect due to the rotation of the Earth. Our project for this goal is called GINGER (gyroscopes in general relativity), and consists of a ground-based triaxial array of ring lasers aimed at measuring the rotation rate of the Earth with an accuracy of 10 −14 rad s −1 . Such an ambitious goal is now within reach, as large-area ring lasers are very close to the required sensitivity and stability. However, demanding constraints on the geometrical stability of the optical path of the laser inside the ring cavity are required. Thus, we have begun a detailed study of the geometry of an optical cavity in order to find a control strategy for its geometry that could meet the specifications of the GINGER project. As the cavity perimeter has a stationary point for the square configuration, we identify a set of transformations on the mirror positions that allows us to adjust the laser beam steering to the shape of a square. We show that the geometrical stability of a square cavity strongly increases by implementing a suitable system to measure the mirror distances, and that the geometry stabilization can be achieved by measuring the absolute lengths of the two diagonals and the perimeter of the ring. (paper)

Deposition of organic dyes for dye-sensitized solar cell by using matrix-assisted pulsed laser evaporation

Directory of Open Access Journals (Sweden)

Chih-Ping Yen

2016-08-01

Full Text Available The deposition of various distinct organic dyes, including ruthenium complex N3, melanin nanoparticle (MNP, and porphyrin-based donor-π-acceptor dye YD2-o-C8, by using matrix-assisted pulsed laser evaporation (MAPLE for application to dye-sensitized solar cell (DSSC is investigated systematically. It is found that the two covalently-bonded organic molecules, i.e., MNP and YD2-o-C8, can be transferred from the frozen target to the substrate with maintained molecular integrity. In contrast, N3 disintegrates in the process, presumably due to the lower bonding strength of metal complex compared to covalent bond. With the method, DSSC using YD2-o-C8 is fabricated, and an energy conversion efficiency of 1.47% is attained. The issue of the low penetration depth of dyes deposited by MAPLE and the possible resolution to it are studied. This work demonstrates that MAPLE could be an alternative way for deposition of organic dyes for DSSC.

Deposition of organic dyes for dye-sensitized solar cell by using matrix-assisted pulsed laser evaporation

Energy Technology Data Exchange (ETDEWEB)

Yen, Chih-Ping [Department of Physics, National Taiwan University, Taipei 106, Taiwan (China); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Yu, Pin-Feng [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Department of Physics, National Chung Cheng University, Chiayi 621, Taiwan (China); Wang, Jyhpyng [Department of Physics, National Taiwan University, Taipei 106, Taiwan (China); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Department of Physics, National Central University, Taoyuan 320, Taiwan (China); Lin, Jiunn-Yuan [Department of Physics, National Chung Cheng University, Chiayi 621, Taiwan (China); Chen, Yen-Mu [SuperbIN Co., Ltd., Taipei 114, Taiwan (China); Chen, Szu-yuan, E-mail: sychen@ltl.iams.sinica.edu.tw [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Department of Physics, National Central University, Taoyuan 320, Taiwan (China)

2016-08-15

The deposition of various distinct organic dyes, including ruthenium complex N3, melanin nanoparticle (MNP), and porphyrin-based donor-π-acceptor dye YD2-o-C8, by using matrix-assisted pulsed laser evaporation (MAPLE) for application to dye-sensitized solar cell (DSSC) is investigated systematically. It is found that the two covalently-bonded organic molecules, i.e., MNP and YD2-o-C8, can be transferred from the frozen target to the substrate with maintained molecular integrity. In contrast, N3 disintegrates in the process, presumably due to the lower bonding strength of metal complex compared to covalent bond. With the method, DSSC using YD2-o-C8 is fabricated, and an energy conversion efficiency of 1.47% is attained. The issue of the low penetration depth of dyes deposited by MAPLE and the possible resolution to it are studied. This work demonstrates that MAPLE could be an alternative way for deposition of organic dyes for DSSC.

Conversion of the luminescence of laser dyes in opal matrices to stimulated emission

International Nuclear Information System (INIS)

Alimov, O K; Basiev, T T; Orlovskii, Yu V; Osiko, V V; Samoilovich, M I

2008-01-01

The luminescence and laser characteristics of a synthetic opal matrix filled with organic dyes are studied upon excitation by nanosecond laser pulses. The appearance of stimulated emission in a partially ordered scattering medium is investigated. It is shown that if the luminescence spectrum of a dye (oxazine-17) is located far outside the photonic bandgap of the opal matrix, stimulated emission along a preferential direction in the (111) plane is observed when pumping exceeds a threshold even without an external optical cavity. The stimulated emission spectrum is considerably narrower than the luminescence spectrum and consists of several narrow lines located within the dye luminescence band. If the luminescence spectrum of a dye (rhodamine 6G) overlaps with the photonic bandgap of the opal matrix, a different picture is observed. The loss of radiation in the matrix leads to the red shift of the luminescence spectrum, while the stimulated emission as in the case of oxazine-17 lies is observed within the luminescence band. (active media, lasers, and amplifiers)

Wavelength-selectable and steady single-mode erbium-doped fiber multiple ring laser

Science.gov (United States)

Yeh, Chien-Hung; Yang, Zi-Qing; Huang, Tzu-Jung; Chow, Chi-Wai; Chen, Jing-Heng; Chen, Kun-Huang

2017-11-01

To achieve a stable and selectable C-band erbium-doped fiber (EDF) laser with single-longitudinal-mode output, a multiple ring architecture is proposed and demonstrated experimentally. In this work, we design a passively quadruple-ring structure in the cavity of an EDF laser to produce a Vernier effect with a mode filter for suppressing the multimode spikes significantly. In addition, the output performance and stability of the proposed EDF ring laser are discussed.

Frequency lock of a dye laser emission on iron atomic line top

International Nuclear Information System (INIS)

Durand, P.

1995-03-01

The aim of this thesis is to realize a frequency lock of a dye laser emission on iron atomic line top. To reach that goal, the author first presents the calculation of atomic vapour density by means of laser absorption ratio measure and studies the dye laser working. It is then necessary to find a device giving the required precision on the frequency of the absorption line choosen. It is obtained thanks to the atomic line reconstitution by optogalvanic effect which gives the reference. Besides, the author presents the necessity of a laser emission power regulation which is obtained thanks to a device including an acoustic and optic modulator. A reliable and accurate captor is choosen and adjusted testing various hollow cathode lamps. The method to obtain the frequency lock of laser emission on iron atomic line top is described. (TEC). 18 refs., 64 figs

Continuous-wave singly resonant optical parametric oscillator placed inside a ring laser

DEFF Research Database (Denmark)

Abitan, Haim; Buchhave, Preben

2003-01-01

A cw singly resonant optical parametric oscillator (SRO) was built and placed inside the cavity of a ring laser. The system consists of a diode-end-pumped Nd:YVO4 ring laser with intracavity periodically poled lithium niobate as the nonlinear gain medium of the SRO. When the laser was operated...... in a unidirectional mode, we obtained more than 520 mW of signal power in one beam. When the laser was operated in a bidirectional mode, we obtained 600 mW of signal power (300 mW in two separate beams). The power and the spectral features of the laser in the unidirectional and bidirectional modes were measured while...... the laser was coupled with the SRO. The results show that it is preferable to couple a SRO with a unidirectional ring laser....

Single mode solid state distributed feedback dye laser fabricated by grey scale electron beam lithography on dye doped SU-8 resist

DEFF Research Database (Denmark)

Balslev, Søren; Rasmussen, Torben; Shi, Peixiong

2005-01-01

We demonstrate grey scale electron beam lithography on functionalized SU-8 resist for fabrication of single mode solid state dye laser devices. The resist is doped with Rhodamine 6G perchlorate and the lasers are based on a first order Bragg grating distributed feedback resonator. The lasers...

Free electron laser and microwave instability interplay in a storage ring

Directory of Open Access Journals (Sweden)

G. L. Orlandi

2004-06-01

Full Text Available Collective effects, such as the microwave instability, influence the longitudinal dynamics of an electron beam in a storage ring. In a storage ring free electron laser (FEL they can compete with the induced beam heating and thus be treated as a further concomitant perturbing source of the beam dynamics. Bunch length and energy spread measurements, carried out at the Super-ACO storage ring, can be correctly interpreted according to a broad-band impedance model. Quantitative estimations of the relative role that is played by the microwave instability and the laser heating in shaping the beam longitudinal dynamics have been obtained by the analysis of the equilibrium laser power. It has been performed in terms of either a theoretical limit, implemented with the measured beam longitudinal characteristics, or the numerical results obtained by a macroparticle tracking code, which includes the laser pulse propagation. Such an analysis, carried out for different operating points of the Super-ACO storage ring FEL, indicates that the laser heating counteracts the microwave instability.

How to prevent dimerization of laser dyes in water? Simulation and organic synthesis

International Nuclear Information System (INIS)

Dare-Doyen, S.

2000-01-01

Xanthenes are widely used as laser dyes in ethanol medium because their photophysical properties there are excellent. On the other hand, when they are dissolved in water, their fluorescence is almost zero on account of the dimerization phenomenon (aggregation of two molecules) which is specific in water although the interaction between the two molecules (these dyes are mainly cations) be repulsive. The first part of this work deals with the dimerization study of two dyes, the 6G rhodamine and the 6G pyronine. Molecular dynamics simulation results (AMBER software) have been compared with those of the NMR; thus it has been possible to describe the geometry of the 6G rhodamine dimer and to identify two structures present in equal quantities for the 6G pyronine dimer. It has been demonstrated that the role of water is essential in the aggregation mechanism; this role can be understood as resulting of the hydrophobic effect. The second part of this work concerns the synthesis of rhodamines which are soluble but not able to dimerize in water at the running concentrations of the laser dyes. At first, aminophenol precursors having hydrophilic ionic groups on modifiable sites have been synthesized without changing their photophysical properties. The synthesis sequence of the 3-(2-alkylamino-4-hydroxyphenyl)propionic acids has not given the waited products but N-(3'-hydroxyphenyl)amino-alkylsulfonic acids have been obtained. Their condensation with the phthalic anhydride has led to dyes of a charge -2 at a pH of 5 in water and which have photophysical properties similar to those of the rhodamine 575 in ethanol and laser emission properties in the emission spectral range of the rhodamine 6G in ethanol. This synthesis work has then led to the preparation of two laser dyes usable in water. (author) [fr

Bio-effects of repetitively pulsed ultra-fast distributed feedback dye lasers

International Nuclear Information System (INIS)

Khan, N.; Ahmad, M.I.; Sheikh, A.

1999-01-01

Results of experimental study showing an unexpected rise in pulses of distributed feedback dye laser (DFDL) output due to temperature accumulation in dye cell during passively Q-Switched, a Mode-locked operation is reported. This unintended increase in number of pulse duration, per pulse energy may cause side-effects when used for selective photo thermolysis. To probe this phenomenon most commonly dye was excited with 10 to 20 pulses of second harmonic of a passively Q-Switched and Mode-locked Nd-YaG laser. The outputs of DFDL and Nd:YaG laser were recorded by Imacon 675-streak camera. The peak of DFDL output pulses was found delayed proportionally from the peak of the NYAG pulses by more than one inter-pulse period of excitation laser. A computer program was used to simulate the experimentally measured delay to estimate thermal decay constants and energy retained by the medium to determine the amount of incremental fluctuations in output. The delay between peaks of Nd:YAG (input) and DFDL(output) pulses was found to vary from 10 to 14 nanoseconds for various cavity lengths. It was found that for smaller inter-pulse periods the effect of gradual build-up satisfies the threshold conditions for some of the pulses that otherwise can not. This may lead to unintended increase in energy fluence causing overexposure-induced side-effects. (author)

The Effect of Glare on Regan Contrast Letter Acuity Scores Using Dye-Based and Reflective Laser Eye Protection

National Research Council Canada - National Science Library

Ghani, Nadeem

2001-01-01

Current laser eye protection devices (LEPDs) are dye-based or reflective. While both technologies block the laser wavelengths, reflective LEPDs generally transmit more visible light than do dye-based LEPDs...

Dye laser spectrometer for the analysis of pulsed vacuum arcs

International Nuclear Information System (INIS)

Hargis, P.J. Jr.; Robertson, M.M.

1975-01-01

A pulsed dye laser spectrometer which is used to obtain detailed single shot spectroscopic measurements of the plasma in a pulsed vacuum arc was developed. The capabilities of this spectrometer are indicated by the detection of laser induced fluorescence signals from 10 6 neutral Ti atoms in the plasma of a pulsed vacuum arc with a Ti anode. (U.S.)

Numerical Modelling of a Bidirectional Long Ring Raman Fiber Laser Dynamics

Science.gov (United States)

Sukhanov, S. V.; Melnikov, L. A.; Mazhirina, Yu A.

2017-11-01

The numerical model for the simulation of the dynamics of a bidirectional long ring Raman fiber laser is proposed. The model is based on the transport equations and Courant-Isaacson-Rees method. Different regimes of a bidirectional long ring Raman fiber laser and long time-domain realizations are investigated.

Does the position of the electron-donating nitrogen atom in the ring system influence the efficiency of a dye-sensitized solar cell? A computational study.

Science.gov (United States)

Biswas, Abul Kalam; Barik, Sunirmal; Das, Amitava; Ganguly, Bishwajit

2016-06-01

We have reported a number of new metal-free organic dyes (2-6) that have cyclic asymmetric benzotripyrrole derivatives as donor groups with peripheral nitrogen atoms in the ring, fluorine and thiophene groups as π-spacers, and a cyanoacrylic acid acceptor group. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were employed to examine the influence of the position of the donor nitrogen atom and π-conjugation on solar cell performance. The calculated electron-injection driving force (ΔG inject), electron-regeneration driving force (ΔG regen), light-harvesting efficiency (LHE), dipole moment (μ normal), and number of electrons transferred (∆q) indicate that dyes 3, 4, and 6 have significantly higher efficiencies than reference dye 1, which exhibits high efficiency. We also extended our comparison to some other reported dyes, 7-9, which have a donor nitrogen atom in the middle of the ring system. The computed results suggest that dye 6 possesses a higher incident photon to current conversion efficiency (IPCE) than reported dyes 7-9. Thus, the use of donor groups with peripheral nitrogen atoms appears to lead to more efficient dyes than those in which the nitrogen atom is present in the middle of the donor ring system. Graphical Abstract The locations of the nitrogen atoms in the donor groups in the designed dye molecules have an important influence on DSSC efficiency.

Amplified spontaneous emission and laser emission from a high optical-gain medium of dye-doped dendrimer

International Nuclear Information System (INIS)

Yokoyama, Shiyoshi; Nakahama, Tatsuo; Mashiko, Shinro

2005-01-01

We measured the amplified spontaneous emission and laser emission from high-gain media of laser-dye encapsulated dendrimers. A highly branched poly(amidoamine) (PAMAM-OH) dendrimer formed a guest-host complex with a conventional laser-dye (DCM), resulting in a high optical-gain. Of particular note was the appearance of a laser threshold, above which a super-narrowed laser spectrum was observed, although laser feedback was caused without any mirror cavity devices. The optical feedback was attributed to spatial confinement of the light due to gain guiding under optical excitation. The laser spectrum clearly indicated a resonant laser-mode with a spectrum linewidth of less than 0.1 nm. This order of spectrum narrowing is comparable to that seen in the laser emission from ordinary laser devices

QUANTITATIVE DETECTION OF ENVIRONMENTALLY IMPORTANT DYES USING DIODE LASER/FIBER-OPTIC RAMAN

Science.gov (United States)

A compact diode laser/fiber-optic Raman spectrometer is used for quantitative detection of environmentally important dyes. This system is based on diode laser excitation at 782 mm, fiber optic probe technology, an imaging spectrometer, and state-of-the-art scientific CCD camera. ...

Hybrid integrated single-wavelength laser with silicon micro-ring reflector

Science.gov (United States)

Ren, Min; Pu, Jing; Krishnamurthy, Vivek; Xu, Zhengji; Lee, Chee-Wei; Li, Dongdong; Gonzaga, Leonard; Toh, Yeow T.; Tjiptoharsono, Febi; Wang, Qian

2018-02-01

A hybrid integrated single-wavelength laser with silicon micro-ring reflector is demonstrated theoretically and experimentally. It consists of a heterogeneously integrated III-V section for optical gain, an adiabatic taper for light coupling, and a silicon micro-ring reflector for both wavelength selection and light reflection. Heterogeneous integration processes for multiple III-V chips bonded to an 8-inch Si wafer have been developed, which is promising for massive production of hybrid lasers on Si. The III-V layer is introduced on top of a 220-nm thick SOI layer through low-temperature wafer-boning technology. The optical coupling efficiency of >85% between III-V and Si waveguide has been achieved. The silicon micro-ring reflector, as the key element of the hybrid laser, is studied, with its maximized reflectivity of 85.6% demonstrated experimentally. The compact single-wavelength laser enables fully monolithic integration on silicon wafer for optical communication and optical sensing application.

Picosecond transient backward stimulated Raman scattering and pumping of femtosecond dye lasers

Science.gov (United States)

Arrivo, Steven M.; Spears, Kenneth G.; Sipior, Jeffrey

1995-02-01

We report studies of transient, backward stimulated, Raman scattering (TBSRS) in solvents with a 10 Hz, 27 ps, 532 nm pump laser. The TBSRS effect was used to create pulses at 545 nm and 630 nm with durations of 2-3 ps and 5-10 μJ of energy. The duration, energy and fluctuations of the Raman pulse were studied as a function of pump energy and focal parameters. A 5 μJ Raman pulse was amplified in either a Raman amplifier or two stage dye amplifier to 1 mJ levels. A 545 nm pulse of 3 ps duration was generated in CCl 4 and was then used to pump a short cavity dye laser (SCDL). The SCDL oscillator and a 5 stage dye amplifier provided a pulse of 700 fs and 400 μJ that was tunable near 590 nm.

Improving the Performance of Gold-Nanoparticle-Doped Solid-State Dye Laser Using Thermal Conversion Effect

Science.gov (United States)

An, N. T. M.; Lien, N. T. H.; Hoang, N. D.; Hoa, D. Q.

2018-04-01

Energy transfer between spherical gold nanoparticles with size of more than 15 nm and molecules of organic dye 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4 H-pyran (DCM) has been studied. Such radiative energy transfer led to high local temperature, giving rise to a bleaching effect that resulted in rapid degradation of the laser medium. Gold nanoparticles were dispersed at concentrations from 5 × 109 particles/mL to 5 × 1010 particles/mL in DCM polymethylmethacrylate polymer using a radical polymerization process with 2,2'-azobis(isobutyronitrile) (AIBN) as initiator. Using the fast thermoelectric cooling method, the laser medium stability was significantly improved. The output stability of a distributed feedback dye laser pumped by second-harmonic generation from a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser was investigated. Moreover, bidirectional energy transfer between gold nanoparticles and dye molecules was observed.

Polymer photonic crystal dye lasers as optofluidic cell sensors

DEFF Research Database (Denmark)

Christiansen, Mads Brøkner; Lopacinska, Joanna M.; Jakobsen, Mogens Havsteen

2009-01-01

Dye doped hybrid polymer lasers are implemented as label free evanescent field biosensors for detection of cells. It is demonstrated that although the coverage is irregular and the cells extend over several lattice constants, the emission wavelength depends linearly on the fraction of the surface...

Laser-induced removal of a dye C.I. Acid Red 87 using n-type WO{sub 3} semiconductor catalyst

Energy Technology Data Exchange (ETDEWEB)

Qamar, M. [Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, KFUPM Box 741, Dhahran 31261 (Saudi Arabia); Gondal, M.A., E-mail: magondal@kfupm.edu.sa [Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, KFUPM Box 741, Dhahran 31261 (Saudi Arabia); Laser Research Laboratory, Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Hayat, K. [Chemistry Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Yamani, Z.H. [Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, KFUPM Box 741, Dhahran 31261 (Saudi Arabia); Laser Research Laboratory, Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Al-Hooshani, K. [Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, KFUPM Box 741, Dhahran 31261 (Saudi Arabia); Chemistry Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)

2009-10-30

Water contamination by organic substances such as dyes is of great concern worldwide due to their utilization in many industrial processes and environmental concerns. To cater the needs for waste water treatment polluted with organic dyes, laser-induced photocatalytic process was investigated for removal of a dye derivative namely Acid Red 87 using n-type WO{sub 3} semiconductor catalyst. The degradation was investigated in aqueous suspensions of tungsten oxide under different experimental conditions using laser instead of conventional UV lamp as an irradiation source. The degradation process was monitored by measuring the change in dye concentration as a function of laser irradiation time by employing UV spectroscopic analysis. The degradation of dye was studied by varying different parameters such as laser energy, reaction pH, substrate concentration, catalyst concentration, and in the presence of electron acceptors such as hydrogen peroxide (H{sub 2}O{sub 2}), and potassium bromate (KBrO{sub 3}). The degradation rates were found to be strongly dependent on all the above-mentioned parameters. Our experimental results revealed that the dye degradation process was very fast (within few minutes) under laser irradiation as compared to conventional setups using broad spectral lamps (hours or days) and this laser-induced photocatalytic degradation method could be an effective means to eliminate the pollutants present in liquid phase. The experience gained through this study could be beneficial for treatment of waste water contaminated with organic dyes and other organic pollutants.

Pulsed dye laser treatment of rosacea using a novel 15 mm diameter treatment beam.

Science.gov (United States)

Bernstein, Eric F; Schomacker, Kevin; Paranjape, Amit; Jones, Christopher J

2018-04-10

The pulsed-dye laser has been used to treat facial redness and rosacea for decades. Recent advances in dye laser technology enable 50% higher output energies supporting 50% larger treatment areas, and beam-diameters up to 15 mm with clinically-relevant fluences. In this study, we investigate this novel pulsed-dye laser using a 15 mm diameter beam for treatment of rosacea. Twenty subjects with erythemato-telangiectatic rosacea were enrolled in the study. A total of 4 monthly treatments were administered, first treating linear vessels with a 3 × 10 mm elliptical beam, then diffuse redness with a 15-mm diameter circular beam. Blinded assessment of digital, cross-polarized photographs taken 2 months following the last treatment was performed using an 11-point clearance scale. Nineteen subjects completed the study. Blinded reviewers correctly identified baseline photos in 55 out of the total of 57 images (96.5%). The blinded reviewers scored 17 of the 19 subjects with an improvement greater than 40%, and 11 of the 19 subjects greater than 50%. The average improvement was 53.9%. Side effects were limited to mild edema, mild to moderate erythema, and mild to moderate bruising. This study demonstrates that a newly designed pulsed-dye laser having a novel 15-mm diameter treatment beam improves the appearance of rosacea with a favorable safety profile. Lasers Surg. Med. 9999:1-5, 2018. © 2018 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc. © 2018 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.

Experimental test of a four-level kinetic model for excited-state intramolecular proton transfer dye lasers

Energy Technology Data Exchange (ETDEWEB)

Costela, A; Munnoz, J M; Douhal, A; Figuera, J M; Acuna, A U [Inst. de Quimica Fisica ' ' Rocasolano' ' , C.S.I.C., Madrid (Spain)

1989-11-01

The nanosecond pulses of a dye laser oscillator based on the excited-state intramolecular proton-transfer reaction (IPT) of salicylamide and 2'-hydroxylphenyl benzimidazole dyes have been studied as a function of several experimental parameters. To explain the operation of this laser a numerical four-level kinetic model was developed until the lasing properties of these dyes, in the presence of a variable oxygen concentration and pumped with a double pulse technique, could be reproduced. This was possible only by assuming that the efficiency of the laser is controlled by the absorption cross-section of a transient state with a lifetime in the nanosecond-picosecond range, which was tentatively identified as a ground state tautomeric species. (orig.).

A self-injected, diode-pumped, solid-state ring laser for laser cooling of Li atoms

Energy Technology Data Exchange (ETDEWEB)

Miake, Yudai; Mukaiyama, Takashi, E-mail: muka@ils.uec.ac.jp [Institute for Laser Science, University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585 (Japan); O’Hara, Kenneth M. [Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802-6300 (United States); Gensemer, Stephen [CSIRO Manufacturing Flagship, Lindfield, NSW 2070 (Australia)

2015-04-15

We have constructed a solid-state light source for experiments with laser cooled lithium atoms based on a Nd:Y V O{sub 4} ring laser with second-harmonic generation. Unidirectional lasing, an improved mode selection, and a high output power of the ring laser were achieved by weak coupling to an external cavity which contained the lossy elements required for single frequency operation. Continuous frequency tuning is accomplished by controlling two piezoelectric transducers (PZTs) in the internal and the external cavities simultaneously. The light source has been utilized to trap and cool fermionic lithium atoms into the quantum degenerate regime.

Amplitude and polarization asymmetries in a ring laser

Science.gov (United States)

Campbell, L. L.; Buholz, N. E.

1971-01-01

Asymmetric amplitude effects between the oppositely directed traveling waves in a He-Ne ring laser are analyzed both theoretically and experimentally. These effects make it possible to detect angular orientations of an inner-cavity bar with respect to the plane of the ring cavity. The amplitude asymmetries occur when a birefringent bar is placed in the three-mirror ring cavity, and an axial magnetic field is applied to the active medium. A simplified theoretical analysis is performed by using a first order perturbation theory to derive an expression for the polarization of the active medium, and a set of self-consistent equations are derived to predict threshold conditions. Polarization asymmetries between the oppositely directed waves are also predicted. Amplitude asymmetries similar in nature to those predicted at threshold occur when the laser is operating in 12-15 free-running modes, and polarization asymmetry occurs simultaneously.

A replacement solvent for dimethylsulfoxide /DMSO/ in CW dye lasers

Energy Technology Data Exchange (ETDEWEB)

Herbelin, J.M.; McKay, J.A.

1981-01-01

The use of propylene glycol carbonate as a replacement solvent for dimethyl sulfoxide in a Coherent model 599-21 CW dye laser has been investigated. Up to 40 milliwatts of single frequency output was achieved at 875 nm.

Pulsed dye laser application in ablation of vascular ectasias of the larynx: a preliminary animal study

Science.gov (United States)

Woo, Peak; Wang, Zhi; Perrault, Donald F., Jr.; McMillan, Kathleen; Pankratov, Michail M.

1995-05-01

Vascular ectasias (dilatation) and vascular lesions of the larynx are difficult to treat with exciting modalities. Varix (enlarged vessel) of the vocal folds, vocal fold hemorrhage, vascular polyp, hemangioma, intubation or contact granuloma are common problems which disturb voice. Current applications of CO2 laser and cautery often damage the delicate vocal fold cover. The 585 nm dermatologic pulsed dye laser may be an ideal substitute. Two adult canines were examined under anesthesia via microlaryngoscopy technique. Pulsed dye laser (SPTL-1a, Candela Laser Corp., Wayland, MA) energy was delivered via the micromanipulator with the 3.1-mm spot size in single pulses of 6, 8, and 10 Joules/cm2 and applied to the vessels of the vocal folds, epiglottis, and arytenoid cartilage. Endoscopic examination was carried out immediately after the treatment and at 4 weeks postoperatively. The animals were sacrificed at 3 weeks, larynges excised, and whole organ laryngeal section were prepared for histology. Pulsed dye laser thrombosed vessels of the vocal fold using 6 or 8 Joules/cm2. Vascular break and leakage occurred at 10 Joules/cm2. Follow up examination showed excellent vessel obliteration or thrombosis without scarring or injury to the overlying tissues. Histologic examination shows vascular thrombosis without inflammation and fibrosis in the vocal fold cover. Pulsed dye laser may have promise in treatment of vascular lesions of the larynx and upper airway.

Modeling of anisotropic properties of double quantum rings by the terahertz laser field.

Science.gov (United States)

Baghramyan, Henrikh M; Barseghyan, Manuk G; Kirakosyan, Albert A; Ojeda, Judith H; Bragard, Jean; Laroze, David

2018-04-18

The rendering of different shapes of just a single sample of a concentric double quantum ring is demonstrated realizable with a terahertz laser field, that in turn, allows the manipulation of electronic and optical properties of a sample. It is shown that by changing the intensity or frequency of laser field, one can come to a new set of degenerated levels in double quantum rings and switch the charge distribution between the rings. In addition, depending on the direction of an additional static electric field, the linear and quadratic quantum confined Stark effects are observed. The absorption spectrum shifts and the additive absorption coefficient variations affected by laser and electric fields are discussed. Finally, anisotropic electronic and optical properties of isotropic concentric double quantum rings are modeled with the help of terahertz laser field.

Numerical investigation of vessel heating using a copper vapor laser and a pulsed dye laser in treating vascular skin lesions

Science.gov (United States)

Pushkareva, A. E.; Ponomarev, I. V.; Isaev, A. A.; Klyuchareva, S. V.

2018-02-01

A computer simulation technique was employed to study the selective heating of a tissue vessel using emission from a pulsed copper vapor laser and a pulsed dye laser. The depth and size of vessels that could be selectively and safely removed were determined for the lasers under examination.

Higher-order paraxial theory of the propagation of ring rippled laser beam in plasma: Relativistic ponderomotive regime

International Nuclear Information System (INIS)

Purohit, Gunjan; Rawat, Priyanka; Chauhan, Prashant; Mahmoud, Saleh T.

2015-01-01

This article presents higher-order paraxial theory (non-paraxial theory) for the ring ripple formation on an intense Gaussian laser beam and its propagation in plasma, taking into account the relativistic-ponderomotive nonlinearity. The intensity dependent dielectric constant of the plasma has been determined for the main laser beam and ring ripple superimposed on the main laser beam. The dielectric constant of the plasma is modified due to the contribution of the electric field vector of ring ripple. Nonlinear differential equations have been formulated to examine the growth of ring ripple in plasma, self focusing of main laser beam, and ring rippled laser beam in plasma using higher-order paraxial theory. These equations have been solved numerically for different laser intensities and plasma frequencies. The well established experimental laser and plasma parameters are used in numerical calculation. It is observed that the focusing of the laser beams (main and ring rippled) becomes fast in the nonparaxial region by expanding the eikonal and other relevant quantities up to the fourth power of r. The splitted profile of laser beam in the plasma is observed due to uneven focusing/defocusing of the axial and off-axial rays. The growths of ring ripple increase when the laser beam intensity increases. Furthermore, the intensity profile of ring rippled laser beam gets modified due to the contribution of growth rate

Second harmonic generation of frequency-locked pulsed dye laser for selective photoionization of T1-203 isotope

International Nuclear Information System (INIS)

Lim, Gwon; Jeong, Do Young; Ko, Kwang Hoon; Kim, Jae Woo; Kim, Taek Soo; Rho, Sipyo; Kim, Cheol Jung

2003-01-01

We have constructed the frequency-locked pulsed dye laser system. It is composed with a GIM-type oscillator and 3 stage longitudinally pumped amplifiers. The pump laser is the second harmonic of pulse Nd:YAG laser at the repetition rate of 6 kHz. Frequency-locking of dye laser oscillator is actively controlled by the feedback loop between a photoionization signal of T1-203 isotope and a wavelength tuning control. The tuning mirror rotates the order of micro degree per a step of step motor. Feedback system for frequency locking is operated with a PC-based control interface, including the data analysis of photoionization signals and the wavelength control using step pumping method for a medical application. Therefor, the dye laser has to be locked at 583.66 nm for SHG or BBO crystal. With the frequency-locking system, the photoionization experiment has been done for more than 10 hours.

Utilizing wheel-ring architecture for stable and selectable single-longitudinal-mode erbium fiber laser

Science.gov (United States)

Yeh, Chien-Hung; Yang, Zi-Qing; Huang, Tzu-Jung; Chow, Chi-Wai

2018-03-01

To achieve a steady single-longitudinal-mode (SLM) erbium-doped fiber (EDF) laser, the wheel-ring architecture is proposed in the laser cavity. According to Vernier effect, the proposed wheel-ring can produce three different free spectrum ranges (FSRs) to serve as the mode-filter for suppressing the densely multi-longitudinal-mode (MLM). Here, to complete wavelength-tunable EDF laser, an optical tunable bandpass filter (OTBF) is utilized inside the cavity for tuning arbitrarily. In addition, the entire output performances of the proposed EDF wheel-ring laser are also discussed and analyzed experimentally.

Intensity and absorbed-power distribution in a cylindrical solar-pumped dye laser

Science.gov (United States)

Williams, M. D.

1984-01-01

The internal intensity and absorbed-power distribution of a simplified hypothetical dye laser of cylindrical geometry is calculated. Total absorbed power is also calculated and compared with laboratory measurements of lasing-threshold energy deposition in a dye cell to determine the suitability of solar radiation as a pump source or, alternatively, what modifications, if any, are necessary to the hypothetical system for solar pumping.

Effect of the background radiation of a copper vapor laser with an unstable resonator on dye lasing

Energy Technology Data Exchange (ETDEWEB)

Elaev, V F; Mirza, S M; Sukhanov, V B; Troitskii, V O; Soldatov, A N

1986-05-01

Results of an experimental study of the emission divergence of a copper vapor laser with an unstable resonator are reported. It is shown that a copper vapor laser beam can be conveniently treated as a pair of components with a divergence higher or lower than a certain optimal value; the percent ratio of the components varies with the pulse repetition frequency. In the case where a copper vapor laser is used to pump a dye laser, the contribution of the component with the higher divergence to dye lasing does not exceed 1 percent. 7 references.

Fiber-ring laser-based intracavity photoacoustic spectroscopy for trace gas sensing.

Science.gov (United States)

Wang, Qiang; Wang, Zhen; Chang, Jun; Ren, Wei

2017-06-01

We demonstrated a novel trace gas sensing method based on fiber-ring laser intracavity photoacoustic spectroscopy. This spectroscopic technique is a merging of photoacoustic spectroscopy (PAS) with a fiber-ring cavity for sensitive and all-fiber gas detection. A transmission-type PAS gas cell (resonant frequency f0=2.68  kHz) was placed inside the fiber-ring laser to fully utilize the intracavity laser power. The PAS signal was excited by modulating the laser wavelength at f0/2 using a custom-made fiber Bragg grating-based modulator. We used this spectroscopic technique to detect acetylene (C2H2) at 1531.6 nm as a proof of principle. With a low Q-factor (4.9) of the PAS cell, our sensor achieved a good linear response (R2=0.996) to C2H2 concentration and a minimum detection limit of 390 ppbv at 2-s response time.

Variations in thermo-optical properties of neutral red dye with laser ablated gold nanoparticles

Science.gov (United States)

Prakash, Anitha; Pathrose, Bini P.; Mathew, S.; Nampoori, V. P. N.; Radhakrishnan, P.; Mujeeb, A.

2018-05-01

We have investigated the thermal and optical properties of neutral red dye incorporated with different weight percentage of gold nanoparticles prepared by laser ablation method. Optical absorption studies confirmed the production of spherical nanoparticles and also the interactions of the dye molecules with gold nanoparticles. The quenching of fluorescence and the reduction in the lifetime of gold incorporated samples were observed and was due to the non-radiative energy transfer between the dye molecules and gold nanoparticles. Dual beam thermal lens technique has been employed to measure the heat diffusion in neutral red with various weight percentage of gold nano sol dispersed in ethanol. The significant outcome of the experiment is that, the overall heat diffusion is slower in the presence of gold nano sol compared to that of dye alone sample. Brownian motion is suggested to be the main mechanism of heat transfer under the present conditions. The thermal diffusivity variations of samples with respect to different excitation power of laser were also studied.

A study of the lasing of dyes under the influence of emission from a copper vapor laser

Energy Technology Data Exchange (ETDEWEB)

Danilova, V I; Kopylova, T N; Maier, G V; Masarnovskii, L V; Soldatov, A N; Sukhanov, V B

1980-01-01

Intense pulsed sources of coherent emission with a continuously tunable wavelength and a high pulse repetition frequency are necessary for atmospheric optics. The use of rhodamine lasing during pumping by a copper dye laser is the most promising. The goals of this work include using the opportunities for improving the lasing properties of dyes pumped by a copper dye laser, choosing dye mixtures that are optimum with respect to their lasing relation, and studying the influence of the dye on their lasing characteristics in order to obtain the optimum energy parameters in the device that is built using a copper vapor laser and an optical attachment. On the basis of an analysis of the equations that describe multiatomic molecular lasing, it is possible to come to a conclusion on the intermolecular processes that determine the lasing effectiveness: singlet-singlet and triplettriplet overabsorption of lasing emission, intercombination (S-T) and internal conversion, and photoconversion in excited electron states. A large probability of emission from the lower singlet state (a large value of the constant of the velocity of radiative decay) is also necessary.

Synthesis and characterisation of new laser dyes

International Nuclear Information System (INIS)

Scala-Valero, Claudine

1997-01-01

Rhodamines are very efficient laser dyes for the red part of the visible spectrum: their fluorescence quantum efficiencies are about hundred per cent. However, their conversion efficiencies in dye amplifier are about fifty per cent, due to the presence of S n electronic level which is responsible of the re-absorption of a part of photons. In this research thesis, the author aims at trying to move this S n level out of the stimulated emission bandwidth. Models have been developed to propose new structures derived from rhodamines and theoretically possessing the desired properties. The so-recommended molecules have then been synthesised and characterised in terms of absorption and fluorescence spectra, of quantum efficiency, and of fluorescence lifetime. Two modifications are proposed for the rhodamine 6G structure, either by grafting methyl substitutes, or by grafting variously substituted amines. The searched result is obtained with the second modification [fr

Plasma diagnostics using laser-excited coupled and transmission ring resonators

International Nuclear Information System (INIS)

Haas, R.A.

1976-01-01

In this paper a simple two-level laser model is used to investigate the frequency response of coupled-cavity laser interferometers. It is found that under certain circumstances, often satisfied by molecular gas lasers, the frequency response exhibits a resonant behavior. This behavior severely complicates the interpretation of coupled-cavity laser interferometer measurements of rapidly varying plasmas. To circumvent this limitation a new type of laser interferometer plasma diagnostic with significantly improved time response was developed. In this interferometer the plasma is located in one arm of a transmission ring resonator cavity that is excited by an externally positioned laser. Thus, the laser is decoupled from the interferometer cavity and the time response of the interferometer is then limited by the Q of the ring resonator cavity. This improved time response is acquired without loss of spatial resolution, but requires a more sensitive signal detector since the laser is no longer used as a detector as it is in conventional coupled-cavity laser interferometers. Thus, the new technique incorporates the speed of the Mach--Zender interferometer and the sensitivity of the coupled-cavity laser interferometer. The basic operating principles of this type of interferometer have been verified using a CO 2 laser

Optical study of planar waveguides based on oxidized porous silicon impregnated with laser dyes

Energy Technology Data Exchange (ETDEWEB)

Chouket, A. [Unite de recherche de Spectroscopie Raman, Departement de Physique, Faculte des Sciences de Tunis, Elmanar 2092, Tunis (Tunisia); Charrier, J. [Laboratoire d' Optronique CNRS-UMR FOTON 6082, Universite de Rennes 1, ENSSAT-6 rue de Kerampont, BP 80518, 22305 Lannion Cedex (France); Elhouichet, H. [Unite de recherche de Spectroscopie Raman, Departement de Physique, Faculte des Sciences de Tunis, Elmanar 2092, Tunis (Tunisia)], E-mail: habib.elhouichet@fst.rnu.tn; Oueslati, M. [Unite de recherche de Spectroscopie Raman, Departement de Physique, Faculte des Sciences de Tunis, Elmanar 2092, Tunis (Tunisia)

2009-05-15

Oxidized porous silicon optical planar waveguides were elaborated and impregnated with rhodamine B and rhodamine 6G. The waveguiding, absorption, and photoluminescence properties of these impregnated waveguides were studied. Successful impregnation of the structure with laser dyes is shown from photoluminescence and reflectivity measurements. Furthermore, the reflectivity spectra prove the homogenous incorporation of both dye molecules inside the pores of the matrices. The refractive indices of waveguide layers were determined before and after dye impregnation to indicate the conservation of guiding conditions. The optical losses in the visible wavelengths are studied as a function of dye concentration. The dye absorption is the main reason for these losses.

Anomalous dependence of the lasing parameters of dye solutions on the spectrum of microsecond pump laser pulses

International Nuclear Information System (INIS)

Tarkovsky, V V; Kurstak, V Yu; Anufrik, S S

2003-01-01

The anomalous dependence of the lasing parameters of ethanol solutions of coumarin, rhodamine, oxazine, and laser dyes of other classes on the spectrum of microsecond pump laser pulses is found. The dependence is determined by the shape of the induced singlet - singlet absorption spectra and absorption spectra of short-lived photoproducts. The elucidation of the influence of these factors makes it possible to choose optimal pump spectra and to enhance the efficiency and stability of microsecond dye lasers. (active media)

Histopathology of the effects of tuneable dye laser on monkey retina

Energy Technology Data Exchange (ETDEWEB)

Smiddy, W.E.; Patz, A.; Quigley, H.A.; Dunkelberger, G.R.

1988-07-01

The tuneable dye laser was used to simulate treatment of choroidal neovascularization and panretinal photocoagulation (PRP) in monkey retina. The histopathologic effects of wavelengths from 560 to 630 nm in juxtafoveal, papillomacular bundle, and nonfoveal areas were investigated. An unexpected observation using high-intensity burns in juxtafoveal and, to a lesser extent, in papillomacular bundle areas was inner retinal damage with 600-nm light. At moderate energy levels, the effect of 600 nm were more comparable with those with other wavelengths and included much less damage to the inner retinal layers. At mild energy levels, the effects were comparable with other wavelengths. During and after the application of the burns, the energy levels and ophthalmoscopic appearances were comparable for each wavelength for the high-, moderate-, and mild-intensity burns. The histopathologic effects of 630-nm light (tuneable dye red) were comparable with those of the standard krypton red (647 nm) laser. Nonmacular and PRP effects were similar with all wavelengths. These results indicate that power levels may need to be reduced when placing 600-nm (orange) laser burns in the macula.

Tracheal anastomosis using indocyanine green dye enhanced fibrinogen with a near-infrared diode laser

Science.gov (United States)

Auteri, Joseph S.; Jeevanandam, Valluvan; Oz, Mehmet C.; Libutti, Steven K.; Kirby, Thomas J.; Smith, Craig R.; Treat, Michael R.

1990-06-01

A major obstacle to lung transplantation and combined heart- lung transplantation is dehiscence of the tracheobronchial anastomosis. We explored the possibility of laser welded anastomoses in canine tracheas in vivo. Laser anastomoses were performed on three-quarter circumferential anterior tracheotomies. A continous wave diode laser (808 +1 nm) at a power density of 9.6 watts/cm was used. Human fibrinogen was mixed with indocyanine green dye (ICG, max absorbance 805 nm) and applied to the anastomosis site prior to laser exposure. Animals were sacrificed at 0, 21 and 28 days post-operatively. At sacrifice weld bursting pressures were measured by raising intratracheal pressure using forced ventilation via an endotracheal tube. Sutured and laser welded anastomoses had similar bursting pressures, and exhibited satisfactory histologic evidence of healing. However, compared to polypropylene sutured controls, the laser welded anastomoses exhibited less peritracheal inflammatory reaction and showed visibly smoother luminal surfaces at 21 and 28 days post- operatively. Tracheal anastomosis using ICG dye enhanced fibrinogen combined with the near-infrared diode laser is a promising extension of the technology of laser tissue fusion and deserves further study.

Improving solar-pumped laser efficiency by a ring-array concentrator

Science.gov (United States)

Tibúrcio, Bruno D.; Liang, Dawei; Almeida, Joana; Matos, Rodrigo; Vistas, Cláudia R.

2018-01-01

We report here a compact pumping scheme for achieving large improvement in collection and conversion efficiency of a Nd:YAG solar-pumped laser by an innovative ring-array solar concentrator. An aspheric fused silica lens was used to further concentrate the solar radiation from the focal region of the 1.5-m-diameter ring-array concentrator to a 5.0-mm-diameter, 20-mm-length Nd:YAG single-crystal rod within a conical-shaped pump cavity, enabling multipass pumping to the laser rod. 67.3-W continuous-wave solar laser power was numerically calculated, corresponding to 38.2-W / m2 solar laser collection efficiency, being 1.22 and 1.27 times more than the state-of-the-art records by both heliostat-parabolic mirror and Fresnel lens solar laser systems, respectively. 4.0% conversion efficiency and 0.021-W brightness figure of merit were also numerically obtained, corresponding to 1.25 and 1.62 times enhancement over the previous records, respectively. The influence of tracking error on solar laser output power was also analyzed.

Tunable organic distributed feedback dye laser device excited through Förster mechanism

Science.gov (United States)

Tsutsumi, Naoto; Hinode, Taiki

2017-03-01

Tunable organic distributed feedback (DFB) dye laser performances are re-investigated and characterized. The slab-type waveguide DFB device consists of air/active layer/glass substrate. Active layer consisted of tris(8-quinolinolato)aluminum (Alq3), 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM) dye, and polystyrene (PS) matrix. Effective energy transfer from Alq3 to DCM through Förster mechanism enhances the laser emission. Slope efficiency in the range of 4.9 and 10% is observed at pump energy region higher than 0.10-0.15 mJ cm-2 (lower threshold), which is due to the amplified spontaneous emission (ASE) and lasing. Typical slope efficiency for lasing in the range of 2.0 and 3.0% is observed at pump energy region higher than 0.25-0.30 mJ cm-2 (higher threshold). The tuning wavelength for the laser emission is ranged from 620 to 645 nm depending on the ASE region.

Long-pulsed dye laser versus long-pulsed dye laser-assisted photodynamic therapy for acne vulgaris: A randomized controlled trial

DEFF Research Database (Denmark)

Haedersdal, M.; Togsverd, K.; Wiegell, S.R.

2008-01-01

Background: Long-pulsed dye laser (LPDL)-assisted photodynamic therapy has been suggested to be superior to laser alone for acne vulgaris but no evidence is available. Objective: To evaluate the efficacy and safety of LPDL alone versus LPDL in photodynamic therapy with methylaminolevulinic acid...... (MAL-LPDL) for acne vulgaris. Methods: Fifteen patients received a series of 3 full-face LPDL treatments and half-face prelaser MAL treatments; the latter being randomly assigned to the left or right side. Results: Inflammatory lesions were reduced more on MAL-LPDL-treated than on LPDL-treated sides...... to draw conclusions about the efficacy of the LPDL, only about the efficacy of MAL-LPDL compared with LPDL alone. Conclusions: MAL-LPDL is slightly superior to LPDL for the treatment of inflammatory acne Udgivelsesdato: 2008/3...

Synthesis and Evaluation of Changes Induced by Solvent and Substituent in Electronic Absorption Spectra of New Azo Disperse Dyes Containig Barbiturate Ring

Directory of Open Access Journals (Sweden)

Hooshang Hamidian

2013-01-01

Full Text Available Six azo disperse dyes were prepared by diazotizing 4-amino hippuric acid and coupled with barbituric acid and 2-thiobarbituric acid. Then, the products were reacted with aromatic aldehyde, sodium acetate, and acetic anhydride, and oxazolone derivatives were formed. Characterization of the dyes was carried out by using UV-Vis, FT-IR, 1H NMR and 13C NMR, and mass spectroscopic techniques. The solvatochromic behavior of azo disperse dyes was evaluated in various solvents. The effects of substituents of aromatic aldehyde, barbiturate, and thiobarbiturate ring on the color of dyes were investigated.

Laser-Cooled Ions and Atoms in a Storage Ring

International Nuclear Information System (INIS)

Kleinert, J.; Hannemann, S.; Eike, B.; Eisenbarth, U.; Grieser, M.; Grimm, R.; Gwinner, G.; Karpuk, S.; Saathoff, G.; Schramm, U.; Schwalm, D.; Weidemueller, M.

2003-01-01

We review recent experiments at the Heidelberg Test Storage Ring which apply advanced laser cooling techniques to stored ion beams. Very high phase-space densities are achieved by three-dimensional laser cooling of a coasting 9 Be + beam at 7.3 MeV. Laser-cooled, trapped Cs atoms are used as an ultracold precision target for the study of ion-atom interactions with a 74 MeV beam of 12 C 6+ ions.

Bistability of self-modulation oscillations in an autonomous solid-state ring laser

International Nuclear Information System (INIS)

Dudetskii, V Yu

2013-01-01

Bistable self-modulation regimes of generation for a ring YAG : Nd chip laser with the counterpropagating waves asymmetrically coupled via backward scattering are simulated numerically. Two branches of bistable self-modulation regimes of generation are found in the domain of the parametric resonance between the selfmodulation and relaxation oscillations. The self-modulation regimes observed in earlier experiments pertain to only one of the branches. Possible reasons for such a discrepancy are considered, related to the influence of technical and natural noise on the dynamics of solid-state ring lasers. (control of laser radiation parameters)

Application of ring lasers to determine the directions to the poles of Earth's rotation

International Nuclear Information System (INIS)

Golyaev, Yu D; Kolbas, Yu Yu

2012-01-01

Application of a ring laser to determine the directions to the poles of Earth's rotation is considered. The maximum accuracy of determining the directions is calculated, physical and technical mechanisms that limit the accuracy are analysed, and the instrumental errors are estimated by the example of ring He — Ne lasers with Zeeman biasing. (laser applications and other topics in quantum electronics)

Continuously tunable S and C+L bands ultra wideband erbium-doped fiber ring laser

International Nuclear Information System (INIS)

Wang, Q; Yu, Q X

2009-01-01

This paper presents an ultra wideband tunable silica-based erbium doped fiber ring laser (EDFRL) that can be continuously tuned in S and C+L bands from 1475 to 1619 nm. It is the first time that a fiber ring laser's tuning range reaches 144 nm using a standard silica-based C-band erbium-doped fiber as gain media. In the laser configuration two isolators are used in the fiber loop for suppressing the ASE in C-band and elevating the lasing gain in S-band. As a result the available lasing wavelength is extended toward the shorter wavelength of the gain bandwidth. The optimized erbium-doped fiber length, output coupling ratio and pumping laser power have been obtained through experimental study. This ring fiber laser has simple configuration, low threshold, flat laser spectral distribution and high signal-to-ASE-noise ratio. The laser will have many potential applications in fiber sensor wavelength interrogation, high-resolution spectroscopy and fiber optic communications

Nd:YAG (2 omega) pumped dye laser using self-filtering unstable resonator

CERN Document Server

Rahimian, K; Hariri, H

2002-01-01

A self-filtering unstable resonator with a magnification of M=-3 in a Nd:YAG (2 omega) dye laser has been studied. The dye solution is Rhodamine 6 G in alcohol with the concentration of 5*10 sub - 3 Mol/lit. The spatial intensity distribution of the resonator has been compared has been compared with that of a plane-parallel resonator of equal length. The output energy in both configurations are comparable (20 mu J ,and 26 mu J ,respectively). A significant difference between these two resonators is the laser beam divergence, where beam divergences of 0.77 mrad for the self-filtering unstable resonator and 1.6 mrad for the plane-parallel resonator have been measured. The brightness corresponding to these two resonators are 1.5* 10 sub 1 1 and 2.2* 10 sub 1 0W.cm sub - 2.Sr sub - 1, and the pulse widths are 7 and 17 ns, respectively. These figures show clearly that laser resonator based on the self-filtering unstable resonator design an increase the laser brightness a factor of 10, with a beam divergence of a f...

Temperature Sensor Using a Multiwavelength Erbium-Doped Fiber Ring Laser

Directory of Open Access Journals (Sweden)

Silvia Diaz

2017-01-01

Full Text Available A novel temperature sensor is presented based on a multiwavelength erbium-doped fiber ring laser. The laser is comprised of fiber Bragg grating reflectors as the oscillation wavelength selecting filters. The performance of the temperature sensor in terms of both wavelength and laser output power was investigated, as well as the application of this system for remote temperature measurements.

A comparative study of pulsed dye laser versus long pulsed Nd:YAG laser treatment in recalcitrant viral warts.

Science.gov (United States)

Shin, Yo Sup; Cho, Eun Byul; Park, Eun Joo; Kim, Kwang Ho; Kim, Kwang Joong

2017-08-01

Viral warts are common infectious skin disease induced by human papillomavirus (HPV). But the treatment of recalcitrant warts is still challenging. In this study, we compared the effectiveness of pulsed dye laser (PDL) and long pulsed Nd:YAG (LPNY) laser in the treatment of recalcitrant viral warts. We retrospectively analyzed the medical records of patients with recalcitrant warts treated with laser therapy between January 2013 and February 2016. Seventy-two patients with recalcitrant warts were evaluated. Thirty-nine patients were treated with pulsed dye laser and thirty-three patients were treated with LPNY laser. The following parameters were used: PDL (spot size, 7 mm; pulse duration, 1.5 ms; and fluence, 10-14 J/cm 2 ) and LPNY (spot size, 5 mm; pulse duration, 20 ms; and fluence, 240-300 J/cm 2 ). Complete clearance of two patients (5.1%) in PDL group, and three patients (9.1%) in LPNY group were observed without significant side effects. The patients who achieved at least 50% improvement from baseline were 20 (51.3%) in PDL and 22 (66.7%) in LPNY, respectively. This research is meaningful because we compared the effectiveness of the PDL and LPNY in the recalcitrant warts. Both PDL and LPNY laser could be used as a safe and alternative treatment for recalcitrant warts.

Laser-Cooled Ions and Atoms in a Storage Ring

Energy Technology Data Exchange (ETDEWEB)

Kleinert, J.; Hannemann, S.; Eike, B.; Eisenbarth, U.; Grieser, M.; Grimm, R.; Gwinner, G.; Karpuk, S.; Saathoff, G.; Schramm, U.; Schwalm, D.; Weidemueller, M., E-mail: m.weidemueller@mpi-hd.mpg.de [Max-Planck-Insitut fuer Kernphysik (Germany)

2003-03-15

We review recent experiments at the Heidelberg Test Storage Ring which apply advanced laser cooling techniques to stored ion beams. Very high phase-space densities are achieved by three-dimensional laser cooling of a coasting {sup 9}Be{sup +} beam at 7.3 MeV. Laser-cooled, trapped Cs atoms are used as an ultracold precision target for the study of ion-atom interactions with a 74 MeV beam of {sup 12}C{sup 6+} ions.

Random laser emission at dual wavelengths in a donor-acceptor dye mixture solution

Directory of Open Access Journals (Sweden)

Sunita Kedia

Full Text Available The work was aimed to generate random laser emissions simultaneously at two wavelengths in a weakly scattering system containing mixture of binary dyes, rhodamine-B (Rh-B and oxazine-170 (O-170 dispersed with ZnO nano-particles serving as scattering centres. Random lasing performances for individual Rh-B dye were extensively studied for varying small signal gain/scatterer density and we found lasing threshold to significantly depend upon number density of dispersed nano-particles. In spite of inefficient pumping, we demonstrated possibility of random lasing in O-170 dye solution on account of resonance energy transfer from Rh-B dye which served as donor. At optimum concentrations of fluorophores and scatterer in dye mixture solution, incoherent random lasing was effectively attained simultaneously at two wavelengths centered 90 nm apart. Dual-emission intensities, lasing thresholds and rate of amplifications could be controlled and made equivalent for both donor and acceptor in dye mixture solution by appropriate choice of concentrations of dyes and scatterers. Keywords: Random lasing, Energy transfer, Rhodamine-B, Oxazine-170, Zinc oxide

Picoseconds pulse generation and pulse width determination processes of a distributed feedback dye laser

International Nuclear Information System (INIS)

Abdul Ghani, B.; Hammadi, M.

2004-08-01

A mathematical model has been developed to describe the dynamic emission of Nd-glass, distributed feedback dye laser (DFDL), and periodical grating temperature. The suggested model allows the investigation of the time behavior of Nd-glass laser and DFDL pulsed. Moreover, it allows studying the effect of the laser input parameters of Nd-glass laser on the spectral characteristics of the output DFDL pulses such as pulse width, delay time, and time separation

Megawatt dye laser oscillator-amplifier system for high resolution spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Drell, P; Chu, S

1979-03-01

Peak powers in excess of 4 MW in the visible and 1.3 MW in the uv with linewidths as narrow as 80 MHz are generated with three YAG pumped amplifier stages following a cw dye oscillator. The laser pulses are nearly Fourier transform limited in frequency space and diffraction limited in coordinate space.

Erbium-doped fiber ring laser with SMS modal interferometer for hydrogen sensing

Science.gov (United States)

Zhang, Ya-nan; Zhang, Lebin; Han, Bo; Peng, Huijie; Zhou, Tianmin; Lv, Ri-qing

2018-06-01

A hydrogen sensor based on erbium-doped fiber ring laser with modal interferometer is proposed. A single mode-multimode-single mode (SMS) modal interferometer structure coated with Pd/WO3 film is used as the sensing head, due to that it is easy to be fabricated and low cost. The sensing structure is inserted into an erbium-doped fiber ring laser in order to solve the problem of spectral confusion and improve the detection limit of the hydrogen sensor based on the SMS modal interferometer. The SMS sensing structure is acted as a fiber band-pass filter. When hydrogen concentration around the sensor is changed, it will induce the refractive index and strain variations of the Pd/WO3 film, and then shift the resonant spectrum of the SMS modal interferometer as well as the laser wavelength of the fiber ring laser. Therefore, the hydrogen concentration can be measured by monitoring the wavelength shift of the laser, which has high intensity and narrow full width half maximum. Experimental results demonstrate that the sensor has high sensitivity of 1.23 nm/%, low detection limit of 0.017%, good stability and excellent repeatability.

Broadband pulsed difference frequency generation laser source centered 3326 nm based on ring fiber lasers

Science.gov (United States)

Chen, Guangwei; Li, Wenlei

2018-03-01

A broadband pulsed mid-infrared difference frequency generation (DFG) laser source based on MgO-doped congruent LiNbO3 bulk is experimentally demonstrated, which employs a homemade pulsed ytterbium-doped ring fiber laser and a continuous wave erbium-doped ring fiber laser to act as seed sources. The experimental results indicate that the perfect phase match crystal temperature is about 74.5∘C. The maximum spectrum bandwidth of idler is about 60 nm with suitable polarization states of fundamental lights. The central wavelength of idlers varies from 3293 nm to 3333 nm over the crystal temperature ranges of 70.4-76∘C. A jump of central wavelength exists around crystal temperature of 72∘C with variation of about 30 nm. The conversion efficiency of DFG can be tuned with the crystal temperature and polarization states of fundamental lights.

High frame rate multi-resonance imaging refractometry with distributed feedback dye laser sensor

DEFF Research Database (Denmark)

Vannahme, Christoph; Dufva, Martin; Kristensen, Anders

2015-01-01

imaging refractometry without moving parts is presented. DFB dye lasers are low-cost and highly sensitive refractive index sensors. The unique multi-wavelength DFB laser structure presented here comprises several areas with different grating periods. Imaging in two dimensions of space is enabled...... by analyzing laser light from all areas in parallel with an imaging spectrometer. With this multi-resonance imaging refractometry method, the spatial position in one direction is identified from the horizontal, i.e., spectral position of the multiple laser lines which is obtained from the spectrometer charged...

The development of the intelligent diagnostic expert system for high power dye-laser MOPA system

International Nuclear Information System (INIS)

Liu Lianhua; Yang Wenxi; Zhang Xiaowei; Dan Yongjun

2014-01-01

A intelligent diagnostic expert system was required to simulate the expert thinking process of solving problem in experiment and to real-time judge the running state of the experiment system. The intelligent diagnostic expert system for dye-laser MOPA system was build with the modular design of separated knowledge base and inference engine, the RETE algorithm rules match, the asynchronous operation, and multithreading technology. The experiment result indicated that the system could real-time analysis and diagnose the running state of dye-laser MOPA system with advantages of high diagnosis efficiency, good instantaneity and strong expansibility. (authors)

White-light laser cooling of ions in a storage ring

International Nuclear Information System (INIS)

Calabrese, R.; Guidi, V.; Lenisa, P.; Grimm, R.; Miesner, H.J.; Mariotti, E.; Siena Univ.; Moi, L.; Siena Univ.

1996-01-01

We propose the use of a white laser for laser cooling of ions in a storage ring. The use of a broad-band laser provides a radiation pressure force with wide velocity capture range and high magnitude, which is promising to improve the performance of both longitudinal and indirect transverse cooling. This wide-range force could also be suitable for direct transverse cooling of low-density beams. (orig.)

The effect of transverse multi-mode oscillation in passively modelocked solid-state lasers

Science.gov (United States)

Agnesi, A.; Reali, G. C.; Gabetta, G.

1992-03-01

We demonstrate that the pulses from a passively mode-locked flashlamp pumped solid-state laser can be considerably shorter using an antiresonant-ring mirror than using a linear cavity with a standard contacted dye-cell mirror, and we suggest that transverse-mode-filtering effects in the antiresonant ring play an important role in explaining this difference.

Ionization mechanism of cesium plasma produced by irradiation of dye laser

International Nuclear Information System (INIS)

Yamada, Jun; Shibata, Kohji; Uchida, Yoshiyuki; Hioki, Yoshiaki; Sahashi, Toshio.

1992-01-01

When a cesium vapor was irradiated by a dye laser which was tuned to the cesium atomic transition line, the number of charged particles produced by the laser radiation was observed. Several sharp peaks in the number of charged particles were observed, which corresponded to the atomic transition where the lower level was the 6P excited atom. The ionization mechanism of the laser-produced cesium plasma has been discussed. An initial electron is produced by laser absorptions of the cesium dimer. When the cesium density is high, many 6P excited atoms are excited by electron collisions. The 6P excited atom further absorbs the laser photon and is ionized through the higher-energy state. As the cesium vapor pressure increases, the resonance effect becomes observable. The 6P excited atom plays dominant role in the ionization mechanism of the laser-produced cesium plasma. (author)

UV laser ablation of silicon carbide ring surfaces for mechanical seal applications

Science.gov (United States)

Daurelio, Giuseppe; Bellosi, Alida; Sciti, Diletta; Chita, Giuseppe; Allegretti, Didio; Guerrini, Fausto

2000-02-01

Silicon carbide ceramic seal rings are treated by KrF excimer laser irradiation. Surface characteristics, induced by laser treatment, depend upon laser fluence, the number of laser pulses, their energy and frequency, the rotation rate of the ring and the processing atmosphere. It was ascertained that silicon carbide has to be processed under an inert atmosphere to avoid surface oxidation. Microstructural analyses of surface and cross section of the laser processed samples showed that the SiC surface is covered by a scale due to the melting/resolidification processes. At high fluence there are no continuous scales on the surfaces; materials is removed by decomposition/vaporization and the ablation depth is linearly dependent on the number of pulses. Different surface morphologies are observed. The evolution of surface morphology and roughness is discussed with reference to compositions, microstructure and physical and optical properties of the ceramic material and to laser processing parameters. Preliminary results on tribological behavior of the treated seals are reported.

Independent tunability of the double-mode-locked cw dye laser.

LENUS (Irish Health Repository)

Bourkoff, E

1979-06-01

We report a new configuration that enables the double-mode-locked cw dye laser to be independently tunable. In addition, the output coupling at each of the two wavelengths can be independently specified. A series of oscillographs shows some interesting features unique to double mode locking and also shows the effects of varying the two cavity lengths with respect to each other.

The theoretical and numerical models of the novel and fast tunable semiconductor ring laser

Science.gov (United States)

Zhu, Jiangbo; Zhang, Junwen; Chi, Nan; Yu, Siyuan

2011-01-01

Fast wavelength-tunable semiconductor lasers will be the key components in future optical packet switching networks. Especially, they are of great importance in the optical network nodes: transmitters, optical wavelength-routers, etc. In this paper, a new scheme of a next-generation fast tunable ring laser was given. Tunable lasers in this design have better wavelength tunability compared with others, for they are switched faster in wavelength and simpler to control with the injecting light from an external distributed Bragg-reflector(DBR). Then some discussion of the waveguide material system and coupler design of the ring laser were given. And we also derived the multimode rate equations corresponding to this scheme by analyzing some characteristics of the semiconductor ring cavity, directionality, nonlinear mode competition, optical injection locking, etc. We did MatLab simulation based on the new rate equations to research the process of mode competition and wavelength switching in the laser, and achieved the basic functions of a tunable laser. Finally some discussion of the impact of several key parameters was given.

The non-planar single-frequency ring laser with variable output coupling

Science.gov (United States)

Wu, Ke-ying; Yang, Su-hui; Wei, Guang-hui

2002-03-01

We put forward a novel non-planar single-frequency ring laser, which consists of a corner cube prism and a specially cut Porro prism made by Nd:YAG crystal. The relative angle between the corner cube and the Porro prism could be adjusted to control the output coupling of the laser resonator and the polarization-state of the output laser. A 1.06 μm single-frequency laser with 1 W output has been obtained.

Free electron laser on the ACO storage ring

International Nuclear Information System (INIS)

Elleaume, P.

1984-06-01

This dissertation presents the design and characteristics of a Free Electron Laser built on the electron storage ring ACO at Orsay. The weak optical gain available (approximately 0.1% per pass) necessitated the use of an optical klystron instead of an undulator and the use of mirror with extremely high reflectivity. The laser characteristics: spectra, micro and macro-temporal structures, transverse structure and power are presented. They are in very good agreement with a classical theory based on the Lorentz force and Maxwell equations [fr

High-power actively Q-switched single-mode 1342 nm Nd:YVO4 ring laser, injection-locked by a cw single-frequency microchip laser.

Science.gov (United States)

Koch, Peter; Bartschke, Juergen; L'huillier, Johannes A

2015-11-30

In this paper we report on the realization of a single-mode Q-switched Nd:YVO4 ring laser at 1342 nm. Unidirectional and single-mode operation of the ring laser is achieved by injection-locking with a continuous wave Nd:YVO4 microchip laser, emitting a single-frequency power of up to 40 mW. The ring laser provides a single-mode power of 13.9 W at 10 kHz pulse repetition frequency with a pulse duration of 18.2 ns and an excellent beam quality (M2 laser, a power of 8.7 W at 671 nm with a pulse duration of 14.8 ns and a beam propagation factor of M2 < 1.1 is obtained. The 671 nm radiation features a long-term spectral width of 75 MHz.

Laser inactivation of periodontal bacteria using photosensitizing dyes

Science.gov (United States)

Golding, Paul S.; Maddocks, L.; King, Terence A.; Drucker, D. B.

1996-12-01

We demonstrate the killing of the oral bacteria Prevotella nigrescens using a photosensitizer and light from a 10 Hz, frequency doubled, Q-switched Nd:YAG pumped dye laser, with modified oscillator to increase output power. This system produced light at wavelengths close to 620 nm, the absorption maximum of the photosensitizing agent, malachite green isothiocyanate, a wavelength that is not significantly absorbed by tissue. A bacterial reduction of 97.5 percent was achieved at an energy density of 0.67 J/cm2 and exposure times of 300 seconds.

UV laser interaction with a fluorescent dye solution studied using pulsed digital holography.

Science.gov (United States)

Amer, Eynas; Gren, Per; Sjödahl, Mikael

2013-10-21

A frequency tripled Q-switched Nd-YAG laser (wavelength 355 nm, pulse duration 12 ns) has been used to pump Coumarin 153 dye solved in ethanol. Simultaneously, a frequency doubled pulse (532 nm) from the same laser is used to probe the solvent perpendicularly resulting in a gain through stimulated laser induced fluorescence (LIF) emission. The resulting gain of the probe beam is recorded using digital holography by blending it with a reference beam on the detector. Two digital holograms without and with the pump beam were recorded. Intensity maps were calculated from the recorded digital holograms and used to calculate the gain of the probe beam due to the stimulated LIF. In addition numerical data of the local temperature rise was calculated from the corresponding phase maps using Radon inversion. It was concluded that about 15% of the pump beam energy is transferred to the dye solution as heat while the rest is consumed in the radiative process. The results show that pulsed digital holography is a promising technique for quantitative study of fluorescent species.

The use of ring lasers for the measurement of relativistic effects

International Nuclear Information System (INIS)

Denisov, V I; Zubrilo, A A; Kravtsov, Nikolai V; Pinchuk, V B

1999-01-01

The possibility of using a ring laser for the investigation of relativistic effects is analysed. It is shown that gravitational experiments permitting a refinement of certain (fundamental) aspects of the theory of gravitation will become possible in the near future. (laser applications and other topics in quantum electronics)

High-speed off-axis holographic cinematography with a copper-vapor-pumped dye laser.

Science.gov (United States)

Lauterborn, W; Judt, A; Schmitz, E

1993-01-01

A series of coherent light pulses is generated by pumping a dye laser with the pulsed output of a copper-vapor laser at rates of as much as 20 kHz. Holograms are recorded at this pulse rate on a rotating holographic plate. This technique of high-speed holographic cinematography is demonstrated by viewing the bubble filaments that appear in water under the action of a sound field of high intensity.

Demonstration of frequency control and CW diode laser injection control of a titanium-doped sapphire ring laser with no internal optical elements

Science.gov (United States)

Bair, Clayton H.; Brockman, Philip; Hess, Robert V.; Modlin, Edward A.

1988-01-01

Theoretical and experimental frequency narrowing studies of a Ti:sapphire ring laser with no intracavity optical elements are reported. Frequency narrowing has been achieved using a birefringent filter between a partially reflecting reverse wave suppressor mirror and the ring cavity output mirror. Results of CW diode laser injection seeding are reported.

Redarkening of port-wine stains 10 years after pulsed-dye-laser treatment

NARCIS (Netherlands)

Huikeshoven, Menno; Koster, Petra H. L.; de Borgie, Corianne A. J. M.; Beek, Johan F.; van Gemert, Martin J. C.; van der Horst, Chantal M. A. M.

2007-01-01

BACKGROUND: Although pulsed-dye-laser therapy is currently the gold standard for the treatment of port-wine stains, few objective data are available on its long-term efficacy. Using objective color measurements, we performed a 10-year follow-up of a previously conducted prospective clinical study of

Distributed-feedback dye laser for picosecond ultraviolet and visible spectroscopy

International Nuclear Information System (INIS)

Yaney, Perry P.; Kliner, Dahv A. V.; Schrader, Paul E.; Farrow, Roger L.

2000-01-01

We describe the design and operation of a tunable, picosecond laser system for use in time-resolved spectroscopic measurements in the visible and ultraviolet (UV) spectral region. The laser is designed for fine tuning and high wavelength stability. A Nd:YAG-pumped distributed-feedback dye laser (DFDL) generates pulses that are ∼100 ps in duration with a nearly transform-limited linewidth (∼5 GHz) at a 20 Hz repetition rate. The DFDL pulses are amplified in two bow-tie amplifiers, providing pulse energies of up to 3.0 mJ; the amplified pulses may be frequency doubled to the UV spectral region, providing up to 1.0 mJ. The DFDL wavelength is computer stabilized to within ±0.8 pm (±0.7 GHz, two standard deviations), allowing the wavelength to be stationed on a narrow atomic or molecular transition or permitting nearly continuous spectral scans. Application of the laser system to studies of OH energy transfer has been demonstrated; both laser-induced-fluorescence and degenerate-four-wave-mixing spectra have been recorded. (c) 2000 American Institute of Physics

Photophysical characterization of pyrromethene 597 laser dye in cross-linked silicon-containing organic copolymers

Energy Technology Data Exchange (ETDEWEB)

Tyagi, A.; Agua, D. del [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetsstrasse 31, 93053 Regensburg (Germany); Penzkofer, A. [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetsstrasse 31, 93053 Regensburg (Germany)], E-mail: alfons.penzkofer@physik.uni-regensburg.de; Garcia, O.; Sastre, R. [Instituto de Ciencia y Tecnologia de Polimeros, CSIC, Juan de la Cierva 3, 28006 Madrid (Spain); Costela, A.; Garcia-Moreno, I. [Instituto de Quimica Fisica ' Rocasolano' , CSIC, Serrano 119, 28006 Madrid (Spain)

2007-12-06

Samples of the dipyrromethene-BF{sub 2} dye PM597 incorporated in copolymers of 3-trimethoxysilylpropyl 2-methylprop-2-enoate (TMSPMA, number of polymerizable CC double bonds: {kappa} = 1) with 2-(2-methylprop-2-enoyloxy)ethyl 2-methylprop-2-enoate (EGDMA, {kappa} = 2), [2-(hydroxymethyl)-3-prop-2-(prop-2-enoyloxymethyl)propyl] prop-2-enoate (PETA, {kappa} = 3), and [3-prop-2-enoyloxy-2,2-bis(prop-2-2-enoyloxymethyl)propyl]prop-2-enoate (PETRA, {kappa} = 4) are characterized. The fluorescence quantum distributions, fluorescence quantum yields, degrees of fluorescence polarization, and fluorescence lifetimes are measured. The radiative lifetimes are calculated from fluorescence lifetime and quantum yield. Absorption coefficient spectra are determined from transmission measurements. Absolute absorption cross-section spectra and dye concentrations are obtained by calibration to the radiative lifetimes and to saturable absorptions. Excited-state absorption cross-sections at 527 nm are determined by saturable absorption measurements. The photo-degradation is studied under cw laser excitation conditions and quantum yields of photo-degradation are extracted. The excited-state absorption cross-sections were found to be rather small, and the photo-stability turned out to be high (up to 3 million excitation cycles before degradation) making this class of dipyrromethene dye-doped polymers attractive active laser media. Structural and thermo-mechanical properties of the materials have been determined by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetry, densitometry, and refractometry. They improve with increasing inter-crossing (copolymerization of TMSPMA with PETA and PETRA). The laser properties of the PM597 doped copolymers were evaluated by transverse pumping with 6 ns laser pulses at 532 nm. The best laser materials resulted to be the 7:3 and 9:1 TMSPMA-monomer copolymers.

Dye-enhanced protein solders and patches in laser-assisted tissue welding.

Science.gov (United States)

Small, W; Heredia, N J; Maitland, D J; Da Silva, L B; Matthews, D L

1997-01-01

This study examines the use of dye-enhanced protein bonding agents in 805 nm diode laser-assisted tissue welding. A comparison of an albumin liquid solder and collagen solid-matrix patches used to repair arteriotomies in an in vitro porcine model is presented. Extrinsic bonding media in the form of solders and patches have been used to enhance the practice of laser tissue welding. Preferential absorption of the laser wavelength has been achieved by the incorporation of chromophores. Both the solder and the patch included indocyanine green dye (ICG) to absorb the 805 nm continuous-wave diode laser light used to perform the welds. Solder-mediated welds were divided into two groups (high power/short exposure and low power/long exposure), and the patches were divided into three thickness groups ranging from 0.1 to 1.3 mm. The power used to activate the patches was constant, but the exposure time was increased with patch thickness. Burst pressure results indicated that solder-mediated and patched welds yielded similar average burst strengths in most cases, but the patches provided a higher success rate (i.e., more often exceeded 150 mmHg) and were more consistent (i.e., smaller standard deviation) than the solder. The strongest welds were obtained using 1.0-1.3 mm thick patches, while the high power/short exposure solder group was the weakest. Though the solder and patches yielded similar acute weld strengths, the solid-matrix patches facilitated the welding process and provided consistently strong welds. The material properties of the extrinsic agents influenced their performance.

A novel, simple and efficient dye laser with low amplified spontaneous emission background for analytical fluorescence and ionization spectroscopy

International Nuclear Information System (INIS)

Matveev, Oleg I.; Omenetto, Nicolo'

1995-01-01

A new, simple, compact and efficient, grazing- incidence type of dye laser is suggested which has a low level of Amplified Spontaneous Emission. By using a Coumarin dye (LD 5000) pumped with a 20 mJ XeCl excimer laser, and a diffraction grating with 3000 grooves/mm, an efficiency of 11%, a spectral bandwidth of 0.6 cm -1 and a tuning range from 458 to 517 nm have been obtained

Spatial-mode switchable ring fiber laser based on low mode-crosstalk all-fiber mode MUX/DEMUX

Science.gov (United States)

Ren, Fang; Yu, Jinyi; Wang, Jianping

2018-05-01

We report an all-fiber ring laser that emits linearly polarized (LP) modes based on the intracavity all-fiber mode multiplexer/demultiplexer (MUX/DEMUX). Multiple LP modes in ring fiber laser are generated by taking advantage of mode MUX/DEMUX. The all-fiber mode MUX/DEMUX are composed of cascaded mode-selective couplers (MSCs). The output lasing mode of the ring fiber laser can be switched among the three lowest-order LP modes by employing combination of a mode MUX and a simple N × 1 optical switch. The slope efficiencies, optical spectra and mode profiles are measured.

Injection seeded, diode pumped regenerative ring Nd:YAG amplifier for spaceborne laser ranging technology development

Science.gov (United States)

Coyle, D. Barry; Kay, Richard B.; Degnan, John J.; Krebs, Danny J.; Seery, Bernard D.

1992-01-01

A small, all solid state, regenerative ring amplifier designed as a prototype for space application is discussed. Novel features include dual side pumping of the Nd:YAG crystal and a triangular ring cavity design which minimizes the number of optical components and losses. The amplifier is relatively small (3 ns round trip time) even though standard optical elements are employed. The ring regeneratively amplifies a 100 ps single pulse by approximately 10(exp 5) at a repetition rate of 10 to 100 Hz. The amplifier is designed to be injection seeded with a pulsed, 100 ps laser diode at 1.06 microns, but another Nd:YAG laser system supplying higher pulse energies was employed for laboratory experiment. This system is a prototype laser oscillator for the Geoscience Laser Ranging System (GLRS) platform. Results on measurements of beam quality, astigmatism, and gain are given.

Photophysical and photochemical study of styrene dyes related to their laser efficiency

International Nuclear Information System (INIS)

Meyer, Martine

1989-01-01

The photophysical and photochemical properties of two styrene dyes: 4-dicyanomethylene-2-methyl-6-p-dimethylamino-styryl-4H-pyran (DCM) and 7-dimethylamino-3-(-p-formyl-styryl)-1,4-benzoxazine-2-one (DFSBO) have been studied. These molecules have electron donor and electron acceptor groups which give to their fluorescent excited state a charge transfer state character. The red shifts of the absorption and fluorescence spectra in polar solvents and the large Stokes shift related to the increase of the dipole moment from the ground state to the singlet excited state have been fully characterised. The absorption spectra of the first excited singlet and triplet states and the quantum yields of the intersystem crossing to the triplet state have been determined. The existence of conformers of the two dyes has been evidenced. The synthesis of DCM leads to the trans isomer which, under light exposure undergoes photo-isomerization to the cis-compound. Their fluorescence lifetimes and the photo-isomerization efficiency are solvent dependent. The DFSBO emission spectra depend greatly on the excitation wavelength. This effect can be explained by the occurrence of two rotational conformers one being stabilised by an intramolecular hydrogen bond. The spectral properties of these two molecules enable us to explain why DCM is a very good laser dye whereas DFSBO has a poor laser efficiency. (author) [fr

Infrared cavity ring-down spectroscopy with a CW diode laser system

NARCIS (Netherlands)

Hemerik, M.M.; Kroesen, G.M.W.; Doebele, H.F.; Muraoka, K.

1999-01-01

We report on the first measurements with our CRDS setup. Although the diode laser system was out of order, we were able to test the most important parts with the use of a CO laser. The first results show a ring-down time of 1.54 ~is, which is in perfect agreement with the predicted reflectivity of

Fluorescence fluctuation of Rhodamine 6G dye for high repetition rate laser excitation

International Nuclear Information System (INIS)

Singh, Nageshwar; Patel, Hemant K.; Dixit, S.K.; Vora, H.S.

2013-01-01

In this paper, fluorescence from Rhodamine 6G dye for stationary and flowing liquid medium, excited by copper vapor laser, operating at 6 kHz pulse repetition frequency, was investigated. Large fluctuations in spectral width (about 5 nm) and spectral intensity in the fluorescence from stationary dye solution were observed, while fluctuations in the spectral width diminish in a flowing dye medium. However, this increases spectral intensity and slightly red shifts the fluorescence peak emission wavelength. Theoretical analysis was carried out to explain the observed results by incorporating the temperature induced refractive index, beam deflection and spectral variation in stationary dye solution. Numerical analysis of thermal load and contour of temperature in the optical pumped region inside the dye cell in stationary, 0.2 and 1.5 m/s flow velocity was also investigated to support our analysis. - Highlights: ► High repetition rate excitation generates inhomogeneity in the gain medium. ► Fluorescence of Rhodamine 6G in stationary and flowing medium was carried out. ► Fluorescence fluctuations lessen in flowing medium in contrast to stationary medium. ► Our theoretical and numerical analysis enlightens the experimented outcome trend.

Results and analysis of free-electron-laser oscillation in a high-energy storage ring

International Nuclear Information System (INIS)

Couprie, M.E.; Velghe, M.; Prazeres, R.; Jaroszynski, D.; Billardon, M.

1991-01-01

A storage-ring free-electron laser at Orsay has been operating since 1989 in the visible wavelength range. In contrast with previous experiments, it operates with positrons and at higher energies (600--800 MeV), with the storage ring Super-ACO (ACO denotes Anneau de Collisions d'Orsay). The optical gain, the laser power, the transverse profile, and the macrotemporal structure of the laser are analyzed. In particular, we show that the gain matrix possesses many off-diagonal elements, which results in lasing on a combination of noncylindrical Gaussian modes. The eigenmode of the laser oscillation is a combination of one or two main Gaussian modes and several higher-order modes, which results in most of the power being extracted in these modes

Colloidal-Quantum-Dot Ring Lasers with Active Color Control.

Science.gov (United States)

le Feber, Boris; Prins, Ferry; De Leo, Eva; Rabouw, Freddy T; Norris, David J

2018-02-14

To improve the photophysical performance of colloidal quantum dots for laser applications, sophisticated core/shell geometries have been developed. Typically, a wider bandgap semiconductor is added as a shell to enhance the gain from the quantum-dot core. This shell is designed to electronically isolate the core, funnel excitons to it, and reduce nonradiative Auger recombination. However, the shell could also potentially provide a secondary source of gain, leading to further versatility in these materials. Here we develop high-quality quantum-dot ring lasers that not only exhibit lasing from both the core and the shell but also the ability to switch between them. We fabricate ring resonators (with quality factors up to ∼2500) consisting only of CdSe/CdS/ZnS core/shell/shell quantum dots using a simple template-stripping process. We then examine lasing as a function of the optical excitation power and ring radius. In resonators with quality factors >1000, excitons in the CdSe cores lead to red lasing with thresholds at ∼25 μJ/cm 2 . With increasing power, green lasing from the CdS shell emerges (>100 μJ/cm 2 ) and then the red lasing begins to disappear (>250 μJ/cm 2 ). We present a rate-equation model that can explain this color switching as a competition between exciton localization into the core and stimulated emission from excitons in the shell. Moreover, by lowering the quality factor of the cavity we can engineer the device to exhibit only green lasing. The mechanism demonstrated here provides a potential route toward color-switchable quantum-dot lasers.

Orthogonal linear polarization tunable-beat ring laser with a superluminescent diode

Energy Technology Data Exchange (ETDEWEB)

Takahashi, Y.; Yoshino, T. [Department of Electronic Engineering, Faculty of Engineering, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376 (Japan)

1997-09-01

An orthogonal linear polarization operated ring laser with a superluminescent diode has been demonstrated to generate a tunable optical beat signal. The ring cavity contains a superluminescent diode as the optical gain medium, Faraday rotators, and a variable phase retarder (Babinet-Soleil compensator). By controlling the retarder, we changed the beat frequency in the range from a few tens of megahertz to 100 MHz. {copyright} 1997 Optical Society of America

Micro-fabricated solid state dye lasers based on a photo-definable polymer

DEFF Research Database (Denmark)

Nilsson, Daniel; Balslev, Søren; Gregersen, Misha Marie

2005-01-01

the commercially available laser dye Rhodamine 6G, which is incorporated into the SU-8 polymer matrix. The single-mode slab waveguide is formed by three-step spin-coating deposition: a buffer layer of undoped SU-8, a core layer of SU-8 doped with Rhodamine, and a cladding layer of undoped SU-8. (c) 2005 Optical...

Enhanced optical confinement of dye-doped dielectric nanoparticles using a picosecond-pulsed near-infrared laser

International Nuclear Information System (INIS)

Kittiravechote, A; Chiang, W-Y; Usman, A; Liau, I; Masuhara, H

2014-01-01

We demonstrate a novel strategy to increase the capability of confining numerous dye-doped polymeric nanobeads (diameter 100 nm) with laser trapping. Unlike most classical works of optical trapping that address mainly the stiffness of the optical trap, our work concerns an increase in the number of particles confined near the laser focus. We developed an imaging system of light scattering in which a condenser lamp was employed to illuminate the focal plane of the objective lens, and the scattering of the incoherent light was specifically measured to determine the number of confined nanobeads. In contrast to preceding work that used mainly continuous-wave or femtosecond-pulsed lasers, we employed a picosecond-pulsed laser with the half-wavelength of the laser particularly falling within the absorption band of the dopant. Our results show that the number of doped nanobeads held by the laser is significantly greater than that of the bare nanobeads of the same dimension. In striking contrast, the confinement of the nanobeads of the two types was comparable when a continuous-wave laser of the same wavelength and power was employed. The number of confined dye-doped nanobeads increased nonlinearly with the power of the pulsed laser; this dependence was fitted satisfactorily with a second-order polynomial. Supported by theoretical analysis, we attribute the enhanced confinement of doped nanobeads in part to an increased effective refractive index resulting from two-photon resonance between the optical field of the laser and the dopant of the nanobead. We envisage that our findings would evoke applications that benefit from controlled confinement or aggregation of nanomaterials with the employment of near-infrared pulsed lasers. (letter)

A single-frequency, ring cavity Tm-doped fiber laser based on a CMFBG filter

International Nuclear Information System (INIS)

Li, Qi; Yan, Fengping; Peng, Wanjing; Liu, Shuo; Feng, Ting; Tan, Siyu; Liu, Peng

2013-01-01

A single-frequency (SF), continuous-wave (CW), ring cavity Tm-doped fiber laser has been proposed and demonstrated. A chirped moiré fiber grating (CMFBG) was used as an ultra-narrow filter in the laser cavity to ensure SF operation. When the launched pump power was fixed at 2 W, this proposed laser was in stable operation with a central wavelength, optical signal-to-noise ratio, and full width at half maximum of 1942.8140 nm, 47 dB, and 0.0522 nm, respectively, with a resolution of 0.05 nm. The maximum output power of this laser is 95 mW, a higher output power is restricted by the optical circulator that is used in the cavity. The SF operation of this laser was confirmed by the self-homodyne method. To the best of the authors’ knowledge, this is the first report on an SF, CW, ring cavity Tm-doped fiber laser with a CMFBG filter. (letter)

Alignment of Duke free electron laser storage ring and optical beam delivery system

International Nuclear Information System (INIS)

Emamian, M.; Hower, N.

1999-01-01

Duke Free Electron Laser Laboratory (DFELL) hosts a 1.1 GeV electron beam storage ring facility which is capable of generating beams in the range of nearly monochromatic gamma rays to high peak power infra red (IR) laser. In this report specifications and procedures for alignment of OK-4 /Duke storage ring FEL wiggler and optical cavity mirrors will be discussed. The OK-4 FEL lasing has demonstrated a series of world record in the last few years. In August of this year the OK-4 FEL successfully commissioned to laser at 193.7 nm. Also in this article, alignment of the γ-ray and UV optical beam delivery system that is currently in progress will be described. (authors)

LASERS: Stimulated emission in a solid-state ring laser with a stimulated Brillouin scattering mirror

Science.gov (United States)

Barashkov, M. S.; Bel'dyugin, Igor'M.; Zolotarev, M. V.; Krymskiĭ, M. I.; Oshkin, S. P.; Umnov, A. F.; Kharchenko, M. A.

1990-06-01

The results are presented of an experimental investigation of a solid-state ring laser with a stimulated Brillouin scattering mirror and lasing initiated by a series of ~ 200-300 ns pulses of 1.06 μm wavelength. It is shown that this laser may be useful for the development of a source with radiation parameters controlled by an external signal (energy, transverse and time structure) and also of a low-threshold mirror for phase self-conjugation of radiation.

Using the ultra-long pulse width pulsed dye laser and elliptical spot to treat resistant nasal telangiectasia.

Science.gov (United States)

Madan, Vishal; Ferguson, Janice

2010-01-01

Thick linear telangiectasia on the ala nasi and nasolabial crease can be resistant to treatment with the potassium-titanyl-phosphate (KTP) laser and the traditional round spot on a pulsed dye laser (PDL). We evaluated the efficacy of a 3 mm x 10 mm elliptical spot using the ultra-long pulse width on a Candela Vbeam(R) PDL for treatment of PDL- and KTP laser-resistant nasal telangiectasia. Nasal telangiectasia resistant to PDL (12 patients) and KTP laser (12 patients) in 18 patients were treated with a 3 mm x 10 mm elliptical spot on the ultra-long pulse pulsed dye laser (ULPDL) utilising long pulse width [595 nm, 40 ms, double pulse, 30:20 dynamic cooling device (DCD)]. Six patients had previously received treatment with both PDL and KTP laser prior to ULPDL (40 treatments, range1-4, mean 2.2). Complete clearance was seen in ten patients, and eight patients displayed more than 80% improvement after ULPDL treatment. Self-limiting purpura occurred with round spot PDL and erythema with KTP laser and ULPDL. Subtle linear furrows along the treatment sites were seen in three patients treated with the KTP laser. ULPDL treatment delivered using a 3 mm x 10 mm elliptical spot was non-purpuric and highly effective in the treatment of nasal telangiectasia resistant to KTP laser and PDL.

Reflective variable optical attenuators and fibre ring lasers for wavelength-division multiplexing systems

Science.gov (United States)

Liu, He Liang

Wavelength division multiplexing (WDM) optical fibre system is an important enabling technology to fulfill the demands for bandwidth in the modern information age. The main objective of this project is to study novel devices with the potential to enhance the performance of WDM systems. In particular, a novel reflective variable optical attenuator (RVOA) used for dynamic gain equalization (DGE) and fibre lasers based on an entirely new type of erbium-doped fibres with ultrawide tuning range were investigated theoretically and experimentally. We proposed a new type of RVOA device which could be potentially integrated with arrayed waveguide grating (AWG) to reduce the cost of DGE substantially. Initially, fibre-based RVOAs, fabricated with optical fibre components such as fibre coupler and Faraday rotator mirror, were investigated theoretically and experimentally. Larger attenuation range up to 22 dB was realized for fibre coupler-based ROVA with a Faraday rotator mirror and its polarization-dependent loss is about 0.5 dB. Then polymeric waveguide-based RVOAs were investigated theoretically and experimentally. Using an epoxy Novolak resin as core material and an UV-cured resin (Norland's NOA61) as cladding material, a polymeric waveguide RVOA was successfully fabricated. The dynamic 15 dB attenuation range was achieved and the PDL was less than 0.2 dB. The measured insertion loss of the polymeric waveguide RVOA was too large (about 18 dB) and was mainly induced by coupling loss, material loss and poor alignment. In the second part of the study, fibre ring lasers with continuous wavelength tuning over wide wavelength range and fibre ring lasers with discrete wavelength tuning were investigated. Tunable lasers are important devices in WDM systems because they could be employed as reserved sources and therefore avoiding the need to stock large inventory of lasers to cover the ITU-wavelength grid. In this project, erbium ions doped bismuth oxide glass fibres instead of

Enhancing the Performance of Distributed Feedback Dye Lasers and Plasmonic V-grooves for Lab-on-a-chip Systems

DEFF Research Database (Denmark)

Smith, Cameron

The ability to perform laboratory operations in compact systems is not only advantageous for the development of diagnostics tools and their production, but also provides unique opportunities to explore the natural world on the micro- and nanoscale. To this end, we focus on two optical schemes: 1...... to the advantages they bring to lab-on-a-chip systems.......) polymer-based distributed feedback (DFB) dye lasers, and 2) plasmonic V-grooves. Regarding the first, DFB dye lasers are well suited to serve as compact, minimal analyte volume and highly sensitive refractive index sensors, where changes occurring in an analyte result in readily measurable shifts...

Real-time monitoring of atom vapor concentration with laser absorption spectroscopy

International Nuclear Information System (INIS)

Fan Fengying; Gao Peng; Jiang Tao

2012-01-01

The technology of laser absorption spectroscopy was used for real-time monitoring of gadolinium atom vapor concentration measurement and the solid state laser pumped ring dye laser was used as optical source. The optical fiber was taken to improve the stability of laser transmission. The multi-pass absorption technology combined with reference optical signal avoided the influence of laser power fluctuation. The experiment result shows that the system based on this detection method has a standard error of 4%. It is proved that the monitoring system provides reliable data for atom vapor laser isotope separation process and the separation efficiency can be improved. (authors)

Nanoimprinted distributed feedback dye laser sensor for real-time imaging of small molecule diffusion

DEFF Research Database (Denmark)

Vannahme, Christoph; Dufva, Martin; Kristensen, Anders

2014-01-01

Label-free imaging is a promising tool for the study of biological processes such as cell adhesion and small molecule signaling processes. In order to image in two dimensions of space current solutions require motorized stages which results in low imaging frame rates. Here, a highly sensitive...... distributed feedback (DFB) dye laser sensor for real-time label-free imaging without any moving parts enabling a frame rate of 12 Hz is presented. The presence of molecules on the laser surface results in a wavelength shift which is used as sensor signal. The unique DFB laser structure comprises several areas...

Peculiarities of the statistics of spectrally selected fluorescence radiation in laser-pumped dye-doped random media

Science.gov (United States)

Yuvchenko, S. A.; Ushakova, E. V.; Pavlova, M. V.; Alonova, M. V.; Zimnyakov, D. A.

2018-04-01

We consider the practical realization of a new optical probe method of the random media which is defined as the reference-free path length interferometry with the intensity moments analysis. A peculiarity in the statistics of the spectrally selected fluorescence radiation in laser-pumped dye-doped random medium is discussed. Previously established correlations between the second- and the third-order moments of the intensity fluctuations in the random interference patterns, the coherence function of the probe radiation, and the path difference probability density for the interfering partial waves in the medium are confirmed. The correlations were verified using the statistical analysis of the spectrally selected fluorescence radiation emitted by a laser-pumped dye-doped random medium. Water solution of Rhodamine 6G was applied as the doping fluorescent agent for the ensembles of the densely packed silica grains, which were pumped by the 532 nm radiation of a solid state laser. The spectrum of the mean path length for a random medium was reconstructed.

Intravenous injection of artificial red cells and subsequent dye laser irradiation causes deep vessel impairment in an animal model of port-wine stain.

Science.gov (United States)

Rikihisa, Naoaki; Tominaga, Mai; Watanabe, Shoji; Mitsukawa, Nobuyuki; Saito, Yoshiaki; Sakai, Hiromi

2018-03-15

Our previous study proposed using artificial blood cells (hemoglobin vesicles, Hb-Vs) as photosensitizers in dye laser treatment for port-wine stains (PWSs). Dye laser photons are absorbed by red blood cells (RBCs) and hemoglobin (Hb) mixture, which potentially produce more heat and photocoagulation and effectively destroy endothelial cells. Hb-Vs combination therapy will improve clinical outcomes of dye laser treatment for PWSs because very small vessels do not contain sufficient RBCs and they are poor absorbers/heaters of lasers. In the present study, we analyzed the relationship between vessel depth from the skin surface and vessel distraction through dye laser irradiation following intravenous Hb-Vs injection using a chicken wattle model. Hb-Vs were administered and chicken wattles underwent high-energy irradiation at energy higher than in the previous experiments. Hb-Vs location in the vessel lumen was identified to explain its photosensitizer effect using human Hb immunostaining of the irradiated wattles. Laser irradiation with Hb-Vs can effectively destroy deep vessels in animal models. Hb-Vs tend to flow in the marginal zone of both small and large vessels. Increasing laser power combined with Hb-Vs injection contributed for deep vessel impairment because of the synergetic effect of both methods. Newly added Hb tended to flow near the target endothelial cells of the laser treatment. In Hb-Vs and RBC mixture, heat transfer to endothelial cells from absorbers/heater may increase. Hb-Vs function as photosensitizers to destroy deep vessels within a restricted distance that the photon can reach.

A new systematic calibration method of ring laser gyroscope inertial navigation system

Science.gov (United States)

Wei, Guo; Gao, Chunfeng; Wang, Qi; Wang, Qun; Xiong, Zhenyu; Long, Xingwu

2016-10-01

Inertial navigation system has been the core component of both military and civil navigation systems. Before the INS is put into application, it is supposed to be calibrated in the laboratory in order to compensate repeatability error caused by manufacturing. Discrete calibration method cannot fulfill requirements of high-accurate calibration of the mechanically dithered ring laser gyroscope navigation system with shock absorbers. This paper has analyzed theories of error inspiration and separation in detail and presented a new systematic calibration method for ring laser gyroscope inertial navigation system. Error models and equations of calibrated Inertial Measurement Unit are given. Then proper rotation arrangement orders are depicted in order to establish the linear relationships between the change of velocity errors and calibrated parameter errors. Experiments have been set up to compare the systematic errors calculated by filtering calibration result with those obtained by discrete calibration result. The largest position error and velocity error of filtering calibration result are only 0.18 miles and 0.26m/s compared with 2 miles and 1.46m/s of discrete calibration result. These results have validated the new systematic calibration method and proved its importance for optimal design and accuracy improvement of calibration of mechanically dithered ring laser gyroscope inertial navigation system.

Fine and hyperfine structure spectra of the ultra-violet 23S → 53P transition in 4He and 3He with a frequency doubled CW ring laser, detected via associative ionization

International Nuclear Information System (INIS)

Runge, S.; Pesnelle, A.; Perdrix, M.; Sevin, D.; Wolffer, N.; Watel, G.

1982-01-01

High resolution laser spectroscopy coupled to a sensitive method of detection via mass analysis of He + 2 ions produced in He(5 3 P) + He(1 1 S) collisions, is used to obtain the fine and hyperfine spectra of the ultra-violet He 2 3 S → 5 3 P transition. A cw tunable UV radiation around 294.5 nm is generated by intracavity frequency doubling a Rhodamine 6G single mode ring dye laser using an ADA crystal. Both spectra enable fine and hyperfine structures to be determined within a few MHz. The magnetic dipole coupling constant A of the 5 3 P term of 3 He is found to be -4326 +- 9 MHz (-0.1443 +- 0.0003 cm -1 ). (orig.)

Fluorescence, Decay Time, and Structural Change of Laser Dye Cresyl Violet in Solution due to Microwave Irradiation at GSM 900/1800 Mobile Phone Frequencies

Directory of Open Access Journals (Sweden)

Fuat Bayrakceken

2012-01-01

Full Text Available Microwave irradiation at GSM 900/1800 MHz mobile phone frequencies affects the electronic structure of cresyl violet in solution. These changes are important because laser-dye cresyl violet strongly bonds to DNA- and RNA-rich cell compounds in nerve tissues. The irradiation effects on the electronic structure of cresyl violet and its fluorescence data were all obtained experimentally at room temperature. For most laser dyes, this is not a trivial task because laser dye molecules possess a relatively complex structure. They usually consist of an extended system of conjugated double or aromatic π-bonds with attached auxochromic (electron donating groups shifting the absorption band further towards longer wavelength. Because of the intrinsically high degree of conjugation, the vibrational modes of the molecular units couple strongly with each other. We found that the fluorescence quantum yield was increased from to due to intramolecular energy hopping of cresyl violet in solution which is exposed to microwave irradiation at mobile phone frequencies, and the photonic product cannot be used as a laser dye anymore.

Photoinduced electric currents in ring-shaped molecules by circularly polarized laser pulses

International Nuclear Information System (INIS)

Nobusada, Katsuyuki; Yabana, Kazuhiro

2007-01-01

We have theoretically demonstrated that circularly polarized laser pulses induce electric currents and magnetic moments in ring-shaped molecules Na 10 and benzene. The time-dependent adiabatic local density approximation is employed for this purpose, solving the time-dependent Kohn-Sham equation in real space and real time. It has been found that the electric currents are induced efficiently and persist continuously even after the laser pulses were switched off provided the frequency of the applied laser pulse is in tune with the excitation energy of the electronic excited state with the dipole strength for each molecular system. The electric currents are definitely revealed to be a second-order nonlinear optical response to the magnitude of the electric field. The magnetic dipole moments inevitably accompany the ring currents, so that the molecules are magnetized. The production of the electric currents and the magnetic moments in the present procedure is found to be much more efficient than that utilizing static magnetic fields

Study of the use of methanol-filled Er-doped suspended-core fibres in a temperature-sensing ring laser system

International Nuclear Information System (INIS)

Martín, J C; Berdejo, V; Vallés, J A; Sánchez-Martín, J A; Díez, A; Andrés, M V

2013-01-01

We report on an experimental/numerical investigation into the use of methanol-filled Er-doped suspended-core fibres (SCFs) in temperature-sensing ring laser systems. We have adopted a ring laser configuration that includes an Er-doped SCF as a temperature-dependent attenuator (TDA) with a step-index Er-doped fibre (EDF) as the laser active medium. The laser performance dependence on the temperature was measured both in continuous wave (CW) and transient regimes. CW laser output power and build-up time values are compared with those of similar laser systems based on other types of Er-doped PCFs or using other laser configurations. A notable variation of 0.73% °C −1 was achieved in CW operation. Then, by means of parameters obtained by numerically fitting the experimental results, the potential sensing performance of the laser configuration with an SCF as a TDA is studied. Moreover, two ring cavity laser configurations (with the SCF acting basically as an attenuator or also as the active media) are compared and the influence of the position of the coupler inside the ring cavity and the contribution of the erbium doping to improve the sensor features are analysed. The longer interaction lengths compatible with laser action using the Er-doped SCF as a TDA could provide variations of laser output power up to 8.6% °C −1 for 90 mW pump power and a 1 m methanol-filled SCF. (paper)

Treatment of port-wine stains with flash lamp pumped pulsed dye laser on Indian skin: A six year study

Directory of Open Access Journals (Sweden)

Chandroth Ponnambath Thajudheen

2014-01-01

Full Text Available Context: Port-wine stain (PWS is one of the commonly encountered congenital cutaneous vascular lesions, with an equal sex distribution. Pulsed dye lasers (PDL have revolutionized the treatment of both congential and acquired cutaneous vascular lesions. The pulsed dye lasers owing to its superior efficacy and safety profile have become the gold standard for the management of port-wine stains. Aims: To evaluate the efficacy and side effects of pulsed dye laser for the management of Port-wine stain on Indian skin. Materials and Methods: Seventy five patients of Fitzpatrick skin types IV&V with PWS underwent multiple treatments with PDL (V beam-Candela over a period of six years at monthly intervals. Laser parameters were wavelength 595nm, spot sizes 7-10mm, fluence 6-12 j/cm2, pulse duration 0.45-10ms, along with cryogen cooling. Serial photographs were taken before and after every session. Clinical improvement scores of comparable photographs using a quartile grading (o=80% were judged independently by two dermatologists after the series of treatment. Minimum number of treatments was 6 and maximum 17.They were followed up at six monthly intervals to observe re darkening of PWS. Results: No patient showed total clearance.Grade3 improvement was observed in 70 % of children and 50% of adults after 8-10 sessions. Children showed better and faster response than adults. Thirty percent of patients developed post inflammatory hyper pigmentation which resolved over a period of six to eight weeks. Two patients had superficial scarring due to stacking of pulses. None of the patients showed re darkening of PWS till now. Conclusion: Pulsed dye laser is an effective and safe treatment for port-wine stain in Indian skin.

Mode structure in an optically pumped D2O far infrared ring laser

International Nuclear Information System (INIS)

Yuan, D.C.; Soumagne, G.; Siegrist, M.R.

1989-07-01

The mode structures in an optically pumped D 2 O far infrared ring laser and a corresponding linear resonator have been compared. While single mode operation can be obtained over the whole useful pressure range in the ring structure, this is only possible at pressures greater than 8 Torr in the linear resonator case. A numerical model predicts quite well the pulse shape, pressure dependence and influence of the resonator quality in the ring cavity. (author) 12 figs., 8 refs

Storage ring free electron laser, pulse propagation effects and microwave type instabilities

International Nuclear Information System (INIS)

Dattoli, G.; Mezi, L.; Renieri, A.; Migliorati, M.

2000-01-01

It has been developed a dynamical model accounting for the storage Ring Free Electron Laser evolution including pulse propagation effects and e-beam instabilities of microwave type. It has been analyzed the general conditions under which the on set of the laser may switch off the instability and focus everybody attention on the interplay between cavity mismatch, laser pulsed behavior and e-beam instability dynamics. Particular attention is also devoted to the laser operation in near threshold conditions, namely at an intracavity level just enough to counteract the instability, that show in this region new and interesting effects arises [it

Laser reflectometry of submegahertz liquid meniscus ringing.

Science.gov (United States)

Farahi, R H; Passian, A; Jones, Y K; Tetard, L; Lereu, A L; Thundat, T G

2009-10-15

Optical techniques that permit nondestructive probing of interfacial dynamics of various media are of key importance in numerous applications such as ellipsometry, mirage effect, and all-optical switching. Characterization of the various phases of microjet droplet formation yields important information for volume control, uniformity, velocity, and rate. The ringing of the meniscus and the associated relaxation time that occurs after droplet breakoff affect subsequent drop formation and is an indicator of the physical properties of the fluid. Using laser reflectometry, we present an analysis of the meniscus oscillations in an orifice of a piezoelectric microjet.

The properties of Ge quantum rings deposited by pulsed laser deposition.

Science.gov (United States)

Ma, Xiying

2010-07-01

SiGe ring-shape nanostructures have attracted much research interest because of the interesting morphology, mechanical, and electromagnetic properties. In this paper, we present the planar Ge nanorings with well-defined sharp edges self-assembled on Si (100) matrix prepared with pulsed laser deposition (PLD) in the present of Ar gas. The transforming mechanism of the droplets is discussed, which a dynamic deformation model has been developed to simulate the self-transforming process of the droplets. The rings were found to be formed in two steps: from droplets to cones and from cones to rings via an elastic self-deforming process, which were likely to be driven by the lateral strain of Ge/Si layers and the surface tension.

Stimulated emission in a solid-state ring laser with an SBS mirror

Science.gov (United States)

Barashkov, M. S.; Bel'Diugin, I. M.; Zolotarev, M. V.; Krymskii, M. I.; Oshkin, S. P.

1990-06-01

Experimental data are presented on a solid-state ring laser with an SBS mirror in the case of the initiation of stimulated emission by a series of pulses 200-300 ns in duration at a wavelength of 1.06 micron. It is shown that this laser can be suitable for the development of a laser source with radiation parameters (energy and transverse and temporal structure) that are controlled by an external signal. It is also suitable for the development of a low-threshold phase-conjugating mirror.

Studies of Lifetimes in an Ion Storage Ring Using Laser Technique

International Nuclear Information System (INIS)

Rostohar, Danijela; Derkatch, Anna; Hartman, Henrik; Norlin, Lars-Olov; Royen, Peder; Schef, Peter; Mannervik, Sven

2003-01-01

The laser-probing method for lifetime measurements of metastable levels, performed by applying the Fast Ion Beam Laser (FIBLAS) method to ions stored in a storage ring, has been developed by the Stockholm group. Recently, we have applied this method to lifetime measurements of close lying metastable levels. In this paper we discuss experimental studies of ions with complex structure and present the first experimentally obtained lifetimes of selected metastable levels in complex systems as Fe + , Eu + and La + .

Use of synchrotron and laser radiations for present and future photoionization studies in excited atoms and ions

International Nuclear Information System (INIS)

Wuilleumier, F.J.

1984-01-01

The status of experiments in photoionization of atoms in excited states is reviewed, with emphasis given to synchrotron and laser photon sources. A technique for exciting the photoionization spectrum of Na atoms using the flux emitted from the bending magnetic of a storage ring is discussed in detail. Some problems in interpreting photoionization spectrum of Ba in the excited state, due to the presence of higher orders are considered. A design approach for a positron storage ring to produce coherent radiation in the VUV is described. It is shown that combined use of a CW dye laser and the positron storage ring will allow new progress to be made in photoionization studies of excited atoms. Some of the experiments to be carried out using the positron storage ring include: measurements of collisional ionization in rare earth metal atoms of low atomic density; photoionization measurements at lower laser powers, leading to an extension of the CW tunability range; and photoionization studies of multiply charged positive ions. 21 references

Controlling the optical field chaos in storage ring free-electron lasers

International Nuclear Information System (INIS)

Wang Wenjie

1995-01-01

The controlling of optical field chaos in a storage ring free-electron laser oscillator is discussed by using a phenomenal model. A novel method (which is called the 'beating method') of controlling chaos in a nonlinear dynamical system described by non-autonomous ordinary differential equations was developed. The result of theoretical analysis and numerical simulation shows that the optical field chaos in a storage ring free-electron laser oscillator can be suppressed and a periodic laser intensity can be obtained when a weak periodic control field is added to the optical cavity. The validity of this method of eliminating chaos is confirmed by the fact that the leading Lyapunov characteristic exponent of the system changes from a positive real number to a negative one. A further research is carried out, and it is found that only when the period of the control field equals to an integral multiple of that of the gain modulation in the optical cavity can the optical field chaos be suppressed. This means that the 'beating method' of controlling chaos is a kind of resonant method. A way to determine the 'best beating position' in the phase trajectory has also been obtained

THERAPY OF SKIN VASCULAR MALFORMATIONS USING COPPER VAPOR LASER AND PULSED DYE LASER

Directory of Open Access Journals (Sweden)

Svetlana V. Klyuchareva

2018-01-01

Full Text Available Aim. Comparison of effectiveness of the application of copper vapor laser (CVL and pulsed dye laser (PDL in clinical practice. Development of choice criteria of the more effective method of treatment.Materials and methods. The clinical data using CVL and PDL in the treatment of skin vascular malformations are presented. The treatment gave good results in removing of dysplastic skin vessels in 2 and 6 months. The treatment was not painful, and patients did not need general and local anesthesia. The results were presented concerning computer modeling of selective heating of vessels in tissue with CVL and PDL radiation. These results allowed to determine the depth of location and dimensions of vessels for selective and secure removing and the safe dosage ranges were found.Results. On the base of the calculated data, one could conclude that the mode of heating of dysplastic vessels with micropulse series of CVL is more safe and effective than the mode of powerful short pulses in the case of PDL.

Numerical analysis of Yb.sup.3+./sup. -sensitized Er.sup.3+./sup. -doped fibre-ring laser

Czech Academy of Sciences Publication Activity Database

Karásek, Miroslav; Kaňka, Jiří

1998-01-01

Roč. 145, č. 2 (1998), s. 133-137 ISSN 1350-2433 R&D Projects: GA AV ČR IAA267403 Keywords : optical fibre s * fibre lasers * numerical analysis * modelling * ring lasers Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.628, year: 1998

GINGER (Gyroscopes IN General Relativity), a ring lasers array to measure the Lense-Thirring effect

Science.gov (United States)

Di Virgilio, Angela D. V.

The purpose of the GINGER is to perform the first test of general relativity (not considering the gravitational redshift measurements) in a terrestrial laboratory, using light as a probe. The experiment will complement the ones in space, performed or under way, with an entirely different technique and at a far lower cost. The methodology is based on ring-lasers, which are extremely accurate rotation sensors and can not only sense purely kinematical rotations (Sagnac effect accounting for the Earth rotation, polar motion of the terrestrial axis, local rotational movements of the laboratory due to the Earth crust dynamics...), but also general relativistic contributions such as the de Sitter effect (coupling between the gravito-electric field of the earth and the kinematical rotation) and the Lense-Thirring effect (inertial frame dragging due to the angular momentum of the earth). In order to reveal the latter effects, ring-laser response must be improved to be able to measure the effective rotation vector (kinematic plus GR terms) with an accuracy of 1 part in 109 or better. This is a challenging technological aspect, which however has been accurately taken into account by designing a system of ring lasers that will be implemented in this project. A ring laser have been installed inside the underground laboratory of GranSasso, with the purpose to see if an underground location is the right choice for GINGER. The apparatus and the preliminary results will be discussed.

Histologic comparison of the pulsed dye laser and copper vapor laser effects on pig skin

Energy Technology Data Exchange (ETDEWEB)

Tan, O.T.; Stafford, T.J.; Murray, S.; Kurban, A.K. (Boston Univ. Medical Center, MA (USA))

1990-01-01

Albino pig skin was exposed to the copper vapor (CVL) and flash-lamp pulsed dye (PDL) lasers at 578 nm with a 3 mm diameter spotsize over a range of fluences until purpura and whitening were first established. The total irradiation time was the parameter that was varied in order for the CVL to reach the desired fluence. The lowest fluence producing each clinical endpoint was designated the threshold fluence: 34 J/cm{sup 2} was required to produce purpura using the CVL compared to 7.5 J/cm{sup 2} with the PDL laser. Histologically, skin exposed to purpura fluences from the CVL revealed the presence of constricted, disrupted papillary dermal blood vessels with trapped RBC's within them which were unlike those exposed to PDL where the irradiated vessels were dilated and packed with masses of intravascular agglutinated RBC's. The whitening threshold fluences for the CVL and PDL lasers were 67 J/cm{sup 2} and 29 J/cm{sup 2}, respectively. Streaming of epidermal cells and dermal collagen denaturation were observed in CVL irradiated skin, compared to occasional dyskeratotic epidermal cells and focal dermal collagen denaturation following PDL exposure. The mechanisms responsible for the clinical and histologic changes produced by the two laser systems are discussed.

Biostimulative effects of Nd:YAG Q-switch dye on normal human fibroblast cultures: study of a new chemosensitizing agent for the Nd:YAG laser

International Nuclear Information System (INIS)

Castro, D.J.; Saxton, R.E.; Fetterman, H.R.; Castro, D.J.; Ward, P.H.

1987-01-01

Kodak Q-switch II is a new chemical with an absorption maxima at 1051 nm, designed to be used as an Nd:YAG dye laser. The potential for this dye as a new chemosensitizing agent in the treatment of connective tissue diseases and wound healing with low energy Nd:YAG laser was examined. Two normal fibroblast cell lines were tested for sensitivity to various levels of this dye in vitro. These cells were exposed to Q-switch II dye at concentrations of 0.01, 0.1, 1, 10, 50, and 100 micrograms/ml for 1 and 24 hours. Cell viability was assessed by the trypan blue exclusion test. Cell duplication and DNA synthesis were measured by the incorporation of [ 3 H]-thymidine at 6 and 24 hours postexposure to Q-switch II dye. At concentrations up to 10 micrograms/ml, both cell lines tested showed no changes in cell viability. However, at concentrations equal or higher than 50 micrograms/ml, more than 40% of the fibroblasts incorporated trypan blue after 24 hours of exposure to this dye, indicating significant cell destruction. The results indicate that Q-switch II dye is nontoxic to normal human fibroblast cultures and showed significant biostimulative effects on cell duplication at concentrations equal to or lower than 10 micrograms/ml. Further studies will be required to determine the usefulness of Q-switch II dye as a new photochemosensitizing agent for potential biostimulation of wound healing and/or treatment of connective tissue diseases with the Nd:YAG laser (near infrared, 1060 nm) at nonthermal levels of energies

Stimulated emission in a solid-state ring laser with an SBS mirror

Energy Technology Data Exchange (ETDEWEB)

Barashkov, M.S.; Bel' diugin, I.M.; Zolotarev, M.V.; Krymskii, M.I.; Oshkin, S.P.

1990-06-01

Experimental data are presented on a solid-state ring laser with an SBS mirror in the case of the initiation of stimulated emission by a series of pulses 200-300 ns in duration at a wavelength of 1.06 micron. It is shown that this laser can be suitable for the development of a laser source with radiation parameters (energy and transverse and temporal structure) that are controlled by an external signal. It is also suitable for the development of a low-threshold phase-conjugating mirror. 5 refs.

χ⁽²⁾ Induced Non-Reciprocal Loss and/or Phase Shift for Unidirectional Operation of Ring Lasers

DEFF Research Database (Denmark)

Tidemand-Lichtenberg, Peter; Cheng, Haynes Pak Hay; Pedersen, Christian

2010-01-01

Numerical modelling and experimental validation of sum-frequency mixing enforcing stable unidirectional operation of a diode pumped solid-state 1342 nm ring laser with improved stability toward feedback.......Numerical modelling and experimental validation of sum-frequency mixing enforcing stable unidirectional operation of a diode pumped solid-state 1342 nm ring laser with improved stability toward feedback....

Single-Frequency Nd:YAG Ring Lasers with Corner Cube Prism

Science.gov (United States)

Wu, Ke-Ying; Yang, Su-Hui; Zhao, Chang-Ming; Wei, Guang-Hui

2000-10-01

We put forward another form of the non-planar ring lasers, in which the corner cube prism is the key element and the Nd:YAG crystal is used as a Porro prism to enclose the ring resonator. The phase shift due to the total internal reflections of the three differently orientated reflection planes of the corner cube prism, Faraday rotation in the Nd:YAG crystal placed in a magnetic field and the different output coupling in S and P polarization form an optical diode and enforce the single-frequency generating power. A round trip analysis of the polarization properties of the resonator is made by the evaluation of Jones matrix.

Effects of diode laser welding with dye-enhanced glue on tensile strength of sutures commonly used in urology.

Science.gov (United States)

Kirsch, A J; Chang, D T; Kayton, M L; Libutti, S K; Connor, J P; Hensle, T W

1996-01-01

Tissue welding using laser-activated protein solders may soon become an alternative to sutured tissue approximation. In most cases, approximating sutures are used both to align tissue edges and provide added tensile strength. Collateral thermal injury, however, may cause disruption of tissue alignment and weaken the tensile strength of sutures. The objective of this study was to evaluate the effect of laser welding on the tensile strength of suture materials used in urologic surgery. Eleven types of sutures were exposed to diode laser energy (power density = 15.9 W/cm2) for 10, 30, and 60 seconds. Each suture was compared with and without the addition of dye-enhanced albumin-based solder. After exposure, each suture material was strained (2"/min) until ultimate breakage on a tensometer and compared to untreated sutures using ANOVA. The strength of undyed sutures were not significantly affected; however, violet and green-dyed sutures were in general weakened by laser exposure in the presence of dye-enhanced glue. Laser activation of the smallest caliber, dyed sutures (7-0) in the presence of glue caused the most significant loss of tensile strength of all sutures tested. These results indicate that the thermal effects of laser welding using our technique decrease the tensile strength of dyed sutures. A thermally resistant suture material (undyed or clear) may prevent disruption of wounds closed by laser welding techniques.

Triphenylamine based benzimidazole and benzothiazole: Synthesis and applications in fluorescent chemosensors and laser dyes

Energy Technology Data Exchange (ETDEWEB)

Yang, Yang [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); University of Chinese Academy of Sciences, Beijing 100039 (China); Li, Bin, E-mail: libinteacher@163.com [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); Zhang, Liming; Guan, Yunlong [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China)

2014-01-15

Triphenylamine based fluorescent dyes TPA-benzimidazole and TPA-benzothiazole have been designed and synthesized. The TPA-benzimidazole chemosensor was tested for a number of metal ions and found to exhibit binding affinity for Fe{sup 3+} and Hg{sup 2+} in acetonitrile, and the fluorescence quenching was achieved through a PET process. The appearance of an isosbestic point in absorption titrations and Job's plot analysis supported 1:1 stoichiometries for Fe{sup 3+} and Hg{sup 2+} ions. Laser experiments showed that under transversal pumping with a Q-switched Nd:YAG (355 nm) laser in toluene, TPA-benzothiazole exhibits efficient and stable amplified spontaneous emissions (ASE) at 436 nm. -- Highlights: • Triphenylamine based fluorescent dyes TPA-benzimidazole and TPA-benzothiazole have been designed and synthesized. • The TPA-benzimidazole exhibits binding affinity for Fe{sup 3+} and Hg{sup 2+} in acetonitrile and the fluorescence quenching was achieved through a PET process. • Under transversal pumping at 355 nm in toluene, TPA-benzothiazole exhibits efficient and stable amplified spontaneous emissions (ASE) in 436 nm.

Triphenylamine based benzimidazole and benzothiazole: Synthesis and applications in fluorescent chemosensors and laser dyes

International Nuclear Information System (INIS)

Yang, Yang; Li, Bin; Zhang, Liming; Guan, Yunlong

2014-01-01

Triphenylamine based fluorescent dyes TPA-benzimidazole and TPA-benzothiazole have been designed and synthesized. The TPA-benzimidazole chemosensor was tested for a number of metal ions and found to exhibit binding affinity for Fe 3+ and Hg 2+ in acetonitrile, and the fluorescence quenching was achieved through a PET process. The appearance of an isosbestic point in absorption titrations and Job's plot analysis supported 1:1 stoichiometries for Fe 3+ and Hg 2+ ions. Laser experiments showed that under transversal pumping with a Q-switched Nd:YAG (355 nm) laser in toluene, TPA-benzothiazole exhibits efficient and stable amplified spontaneous emissions (ASE) at 436 nm. -- Highlights: • Triphenylamine based fluorescent dyes TPA-benzimidazole and TPA-benzothiazole have been designed and synthesized. • The TPA-benzimidazole exhibits binding affinity for Fe 3+ and Hg 2+ in acetonitrile and the fluorescence quenching was achieved through a PET process. • Under transversal pumping at 355 nm in toluene, TPA-benzothiazole exhibits efficient and stable amplified spontaneous emissions (ASE) in 436 nm

Complete electromagnetically induced transparency in sodium atoms excited by a multimode dye laser

International Nuclear Information System (INIS)

Alzetta, G.; Gozzini, S.; Lucchesini, A.; Cartaleva, S.; Karaulanov, T.; Marinelli, C.; Moi, L.

2004-01-01

Complete electromagnetically induced transparency (EIT) in sodium vapor is demonstrated experimentally by means of excitation with a broadband multimode dye laser tuned on the D 1 line. One hundred percent transparency is observed by excitation of the Na vapor with circularly polarized laser light. The linear polarization excitation produces, instead, complete destruction of the EIT resonance. For laser power density in the 0.1 to 1 W/cm 2 range, the linewidth of the EIT resonance remains in the interval of 90-400 kHz. This complete transparency of the medium in a narrow frequency interval is interesting for many applications where the enhancement of the refractive index is important and where the improvement of the signal-to-noise ratio of the dark resonances allows a more sensitive measurement of weak magnetic fields

Polymer-Optical-Fiber Lasers and Amplifiers Doped with Organic Dyes

Directory of Open Access Journals (Sweden)

Joseba Zubia

2011-07-01

Full Text Available Polymer optical fibers (POFs doped with organic dyes can be used to make efficient lasers and amplifiers due to the high gains achievable in short distances. This paper analyzes the peculiarities of light amplification in POFs through some experimental data and a computational model capable of carrying out both power and spectral analyses. We investigate the emission spectral shifts and widths and on the optimum signal wavelength and pump power as functions of the fiber length, the fiber numerical aperture and the radial distribution of the dopant. Analyses for both step-index and graded-index POFs have been done.

[Reduction of decentration after LASIK using a modified eye tracker ring for the MEL-70 excimer laser].

Science.gov (United States)

Schulze, S; Nietgen, G; Sekundo, W

2004-07-01

The aim of this study was to determine and compare the rate of eccentric laser ablation after LASIK depending on the eye tracker ring used. All LASIK treatments were carried out using the MEL-70 flying spot excimer laser (Zeiss-Meditec, Jena). The flap was produced using a Corneal Shaper trade mark or Hansatome trade mark Microkeratome (B and L Surgical, Heidelberg). Initially we used an 11 mm eye tracker ring without hinge protector. At the end of February 2001 this ring was replaced by a 10 mm and a 9.5 mm ring with built-in hinge protector. An additional modification was introduced by us: at 1 mm separations little teeth-like spikes were engraved into the eyeward side of the ring, thus stabilising the position of the ring on the globe and allowing free liquid to flow through the spaces between each spike. The built-in calibration system of the corneal topography (TMS 3, Tomey, Erlangen) from patients with a follow-up of one month or longer was used to determine the distance between the centre of the ablation zone from the fixation point. In group I patients (old ring) 42 eyes were treated. In 4 eyes ablation was perfect, in 21 eyes the ablation centre was located 0.1 to 0.49 mm from the fixation point, in 11 eyes 0.51 to 0.99 mm and in 5 eyes 1.1 to 1.49 mm whereas one eye showed a decentred ablation of 1.53 mm. In group II (new ring) 42 eyes were investigated also. In 11 eyes ablation was perfect, in 20 eyes the ablation centre was located 0.1 to 0.49 mm from the fixation point, in 10 eyes 0.5 to 0.99 mm and one eye had an eccentric ablation of 1.28 mm from the fixation point. The further development of our eye tracker ring for the MEL-70 laser considerably reduced the rate of decentred ablations. An enhanced grip of the ring onto the globe reduces a slow slide during the laser procedure.

A new method to induce transitions in muonic atoms using a high-power tunable dye laser coupled to a stopping muon beam

CERN Document Server

Bertin, A; Duclos, J; Gastaldi, Ugo; Gorini, G; Neri, G; Picard, J; Pitzurra, O; Placci, A; Polacco, E; Stefanini, G; Torelli, G; Vitale, A; Zavattini, E

1974-01-01

An apparatus is described in which a ruby-pumped dye laser is used to induce transitions from the 2S to the 2P levels of the muonic ion ( mu He)/sup +/. The dye laser supplies infra-red radiation pulses in the wavelengths (8040-8180) AA, at typical repetition rates of 1 pulse every 4 s, with an energy release per pulse of 300 mJ for 1.2 J pumping energy. A special synchronization procedure is followed to trigger the laser in close coupling with the incoming muon beam which is stopped in a helium target at pressures between 40 and 50 atm. The other performances of the device are fully discussed with reference both to the laser facility and to the special high-pressure helium target. (23 refs).

Generation of picosecond pulses and frequency combs in actively mode locked external ring cavity quantum cascade lasers

International Nuclear Information System (INIS)

Wójcik, Aleksander K.; Belyanin, Alexey; Malara, Pietro; Blanchard, Romain; Mansuripur, Tobias S.; Capasso, Federico

2013-01-01

We propose a robust and reliable method of active mode locking of mid-infrared quantum cascade lasers and develop its theoretical description. Its key element is the use of an external ring cavity, which circumvents fundamental issues undermining the stability of mode locking in quantum cascade lasers. We show that active mode locking can give rise to the generation of picosecond pulses and phase-locked frequency combs containing thousands of the ring cavity modes

Parametric study of the damage ring pattern in fused silica induced by multiple longitudinal modes laser pulses

Energy Technology Data Exchange (ETDEWEB)

Chambonneau, M., E-mail: maxime.chambonneau@hotmail.fr; Grua, P.; Rullier, J.-L.; Lamaignère, L. [CEA CESTA, 15 Avenue des Sablières, CS 60001, 33116 Le Barp Cedex (France); Natoli, J.-Y. [Aix Marseille Université, CNRS, Centrale Marseille, Institut Fresnel, UMR 7249, 13013 Marseille (France)

2015-03-14

With the use of multiple longitudinal modes nanosecond laser pulses at 1064 nm, laser damage sites at the exit surface of fused silica clearly and systematically exhibit ring patterns. It has been shown in our previous works that the apparent chronology of rings was closely related to the temporal shape of the laser pulses. This particular correspondence had suggested an explanation of the ring morphology formation based on the displacement of an ionization front in the surrounding air. To provide a former basis for this hypothesis and deeper understanding of ring pattern formation, additional experiments have been performed. First, the impact of fluence has been investigated, revealing that a wide variety of damage sites are produced within a very narrow fluence range; this fact involves the chronology of appearance of a surface plasma during the laser pulse. The sizes of the damage sites are proportional to the fluence of their expansion occurring between the beginning of the plasma and the end of the laser pulse. Second, specific experiments have been carried out at different angles of incidence, resulting in egg-shaped patterns rather than circular ones. This behavior can be explained by our previous hypothesis of creation of a plasma in air, its expansion being tightly conditioned by the illumination angle. This series of experiments, in which the angle of incidence is varied up to 80°, permits us to link quantitatively the working hypothesis of ionization front propagation with theoretical hydrodynamics modeling.

Use of reflectance spectrophotometry to predict the response of port wine stains to pulsed dye laser.

Science.gov (United States)

Halachmi, Shlomit; Azaria, Ron; Inbar, Roy; Ad-El, Dean; Lapidoth, Moshe

2014-01-01

Reflectance spectroscopy can be used to quantitate subtle differences in color. We applied a portable reflectance spectrometer to determine its utility in the evaluation of pulsed dye laser treatment of port wine stains (PWS) and in prediction of clinical outcome, in a prospective study. Forty-eight patients with PWS underwent one to nine pulsed dye laser treatments. Patient age and skin color as well as PWS surface area, anatomic location, and color were recorded. Pretreatment spectrophotometric measurements were performed. The subjective clinical results of treatment and the quantitative spectrophotometry results were evaluated by two independent teams, and the findings were correlated. The impact of the clinical characteristics on the response to treatment was assessed as well. Patients with excellent to good clinical results of laser treatments had pretreatment spectrophotometric measurements which differed by more than 10%, whereas patients with fair to poor results had spectrophotometric measurements with a difference of of less than 10%. The correlation between the spectrophotometric results and the clinical outcome was 73% (p Spectrophotometry has a higher correlation with clinical outcome and a better predictive value than other nonmeasurable, nonquantitative, dependent variables.

Thermal Dynamics of Xanthene Dye in Polymer Matrix Excited by Double Pulse Laser Radiation

Science.gov (United States)

Samusev, Ilia; Borkunov, Rodion; Tsarkov, Maksim; Konstantinova, Elizaveta; Antipov, Yury; Demin, Maksim; Bryukhanov, Valery

2018-01-01

Double-pulse laser excitation of the eosin and silver nanoparticles embedded into polymer media is known to be a method of electronic-vibrational energy deactivation kinetic process information obtaining and polymer thermal dynamics investigation. We have studied the vibrational relaxation processes in dye molecules (eosin) and nanoparticles in polyvinyl alcohol after two time-shifted laser pulses with fast and delayed fluorescence kinetics study. In order to simulate thermal and photophysical processes caused by double photon excitation, we solved heat transfer and energy deactivation differential equations numerically. The simulation allowed us to obtain the value of heat conductivity coefficient of polymer matrix.

An asymmetric integrated extended cavity 20GHz mode-locked quantum well ring laser fabricated in the JePPIX technology platform

NARCIS (Netherlands)

Tahvili, M.S.; Barbarin, Y.; Ambrosius, H.P.M.M.; Smit, M.K.; Bente, E.A.J.M.; Leijtens, X.J.M.; Vries, de T.; Smalbrugge, E.; Bolk, J.

2011-01-01

In this paper, we present mode-locked operation of a monolithic 20GHz integrated extended cavity ring laser. The 4mm-long laser ring cavity incorporates a 750µm-long optical amplifier section (SOA), a separate 40µm long saturable absorber (SA) section, passive waveguide sections (shallow and deep

5-GHz passively mode-locked quantum dot ring laser diode at 1.5 μm

NARCIS (Netherlands)

Heck, M.J.R.; Renault, A.; Bente, E.A.J.M.; Oei, Y.S.; Smit, M.K.; Eikema, K.S.E.; Ubachs, W.; Anantathanasarn, S.; Nötzel, R.

2008-01-01

In this paper we present the first observation of passive mode-locking in a quantum dot (QD) ring laser operating at wavelengths around 1.5 µm. The device consists of an 18-mm long (electrically pumped) ring cavity, corresponding to a 5-GHz roundtrip frequency. The waveguide width is 2 µm. A

Injection Characterization of Packaged Bi-Directional Diamond Shaped Ring Laser at 1550 NM

National Research Council Canada - National Science Library

Bussjager, Rebecca; Erdmann, Reinhard; Kovanis, Vassillios; McKeon, Brian; Fanto, Michael; Johns, Steve; Hayduk, Michael J; Osman, Joseph; Morrow, Alan; Green, Malcolm

2006-01-01

The Air Force Research Laboratory. Binoptics Corp. and Infotonics Technology Center worked collaboratively to package and characterize recently developed diode based ring lasers that operate at 1550 nm in a diamond shaped cavity...

Combined pulsed dye laser and fiberoptic Nd-YAG laser for the treatment of hypertrophic port wine stain.

Science.gov (United States)

Radmanesh, Mohammed; Radmanesh, Ramin

2017-10-01

The hypertrophic Port Wine Stain (PWS) is only partially and superficially treated with the Pulsed dye laser (PDL) because of its limited depth of penetration. We used combined PDL and fiberoptic 1444-nm Nd-YAG laser to treat a case with hypertrophic PWS. After tumescent anesthesia, few holes were made by a 16-gauge needle on different sides of the lesion. The fiberoptic tip of 1444-nm Nd-YAG laser was inserted within the holes and was pushed forward while triggering. In a fan pattern and by a back and forth movement, the subcutaneous and deep dermal areas were coagulated. The skin and outer mucosal surfaces were then treated by PDL. The fiberoptic system used was Accusculpt 1444-nm Nd-YAG laser (Lutronic lasers, South Korea), and the PDL used was 585 nm Nlite system (Chromogenex UK). The parameters used for PDL were fluence = 9 Joules/cm 2 and the spot size was 5 mm. The parameters used for fiberoptic 1444-nm Nd-YAG laser were: Pulse rate = 30 Hz, pulse energy = 300 mJ, power = 6 W, and the total energy = 4000 J for the whole face and mucosa. Little sign of regression and moderate purpura were detected immediately after combined fiberoptic Nd-YAG and PDL therapy. The lesion gradually regressed within 4 months with satisfactory color and volume change. Combined fiberoptic Nd-YAG laser and PDL can be used for the treatment of deeper and superficial layers of hypertrophic PWS.

Tests of a grazing-incidence ring resonator free-electron laser

International Nuclear Information System (INIS)

Dowell, D.H.; Laucks, M.L.; Lowrey, A.R.; Adamski, J.L.; Pistoresi, D.J.; Shoffstall, D.R.; Bentz, M.P.; Burns, R.H.; Guha, J.; Sun, K.; Tomita, W.

1991-01-01

This paper reports on the Boeing free-electron laser (FEL) optical cavity that has been changed from a simple concentric cavity using two spherical mirrors to a larger grazing-incidence ring resonator. The new resonator consists of two mirror telescopes located at each end of the wiggler with a round-trip path length of approximately 133 m. Each telescope is a grazing-incidence hyperboloid followed by a normal-incidence paraboloid. Initial tests showed that poorly positioned ring focus and unreliable pointing alignment resulted in reduced and structured FEL output. (First lasing operation occurred on March 23 and 24, 1990.) Later efforts concentrated on improving the resonator alignment techniques and lowering the single-pass losses. FEL performance and reliability have significantly improved due to better ring alignment. The alignment procedure and recent lasing results are described. The effect the electron beam has on lasing is also discussed. Measurements are presented showing how FEL temporal output and wavelength are sensitive to electron beam energy variations

Highly optimized tunable Er3+-doped single longitudinal mode fiber ring laser, experiment and model

DEFF Research Database (Denmark)

Poulsen, Christian; Sejka, Milan

1993-01-01

A continuous wave (CW) tunable diode-pumped Er3+-doped fiber ring laser, pumped by diode laser at wavelengths around 1480 nm, is discussed. Wavelength tuning range of 42 nm, maximum slope efficiency of 48% and output power of 14.4 mW have been achieved. Single longitudinal mode lasing...... with a linewidth of 6 kHz has been measured. A fast model of erbium-doped fiber laser was developed and used to optimize output parameters of the laser...

Exploring the relevance of thiophene rings as bridge unit in acceptor-bridge-donor dyes on self-aggregation and performance in DSSCs.

Science.gov (United States)

Zarate, Ximena; Saavedra-Torres, Mario; Rodriguez-Serrano, Angela; Gomez, Tatiana; Schott, Eduardo

2018-04-30

The possibility of dye charge recombination in DSSCs remains a challenge for the field. This consists of: (a) back-transfer from the TiO 2 to the oxidized dye and (b) intermolecular electron transfer between dyes. The latter is attributed to dye aggregation due to dimeric conformations. This leads to poor electron injection which decreases the photocurrent conversion efficiency. Most organic sensitizers are characterized by an Acceptor-Bridge-Donor (A-Bridge-D) arrangement that is commonly employed to provide charge separation and, therefore, lowering the unwanted back-transfer. Here, we address the intermolecular electron transfer by studying the dimerization and photovoltaic performance of a group of A-Bridge-D structured dyes. Specifically, eight famous sulfur containing π-bridges were analyzed (A and D remained fixed). Through quantum mechanical and molecular dynamics approaches, it was found that the formation of weakly stabilized dimers is allowed. The dyes with covalently bonded and fused thiophene rings as Bridges, 6d and 7d as well as 8d with a fluorene, would present high aggregation and, therefore, high probability of recombination processes. Conversely, using TiO 2 cluster and surface models, delineated the shortest bridges to improve the adsorption energy and the stability of the system. Finally, the elongation of the bridge up to 2 and 3 units and their photovoltaic parameters were studied. These results showed that all the sensitizers are able to provide similar photocurrent outcomes, regardless of whether the bridge is elongated. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Rapid-swept CW cavity ring-down laser spectroscopy for carbon isotope analysis

International Nuclear Information System (INIS)

Tomita, Hideki; Watanabe, Kenichi; Takiguchi, Yu; Kawarabayashi, Jun; Iguchi, Tetsuo

2006-01-01

With the aim of developing a portable system for an in field isotope analysis, we investigate an isotope analysis based on rapid-swept CW cavity ring-down laser spectroscopy, in which the concentration of a chemical species is derived from its photo absorbance. Such a system can identify the isotopomer and still be constructed as a quite compact system. We have made some basic experimental measurements of the overtone absorption lines of carbon dioxide ( 12 C 16 O 2 , 13 C 16 O 2 ) by rapid-swept cavity ring-down spectroscopy with a CW infrared diode laser at 6,200 cm -1 (1.6 μm). The isotopic ratio has been obtained as (1.07±0.13)x10 -2 , in good agreement with the natural abundance within experimental uncertainty. The detection sensitivity in absorbance has been estimated to be 3x10 -8 cm -1 . (author)

Detecting mode hopping in single-longitudinal-mode fiber ring lasers based on an unbalanced fiber Michelson interferometer.

Science.gov (United States)

Ma, Mingxiang; Hu, Zhengliang; Xu, Pan; Wang, Wei; Hu, Yongming

2012-10-20

A method of detecting mode hopping for single-longitudinal-mode (SLM) fiber ring lasers has been proposed and experimentally demonstrated. The method that is based on an unbalanced Michelson interferometer (MI) utilizing phase generated carrier modulation instantly transforms mode-hopping dynamics into steep phase changes of the interferometer. Multiform mode hops in an SLM erbium-doped fiber ring laser with an 18.6 MHz mode spacing have been detected exactly in real-time domain and discussed in detail. Numerical results show that the MI-based method has a high testing sensitivity for identifying mode hopping, which will play a significant role in evaluating the output stability of SLM fiber lasers.

Coumarin-BODIPY hybrids by heteroatom linkage: versatile, tunable and photostable dye lasers for UV irradiation.

Science.gov (United States)

Esnal, I; Duran-Sampedro, G; Agarrabeitia, A R; Bañuelos, J; García-Moreno, I; Macías, M A; Peña-Cabrera, E; López-Arbeloa, I; de la Moya, S; Ortiz, M J

2015-03-28

Linking amino and hydroxycoumarins to BODIPYs through the amino or hydroxyl group lets the easy construction of unprecedented photostable coumarin-BODIPY hybrids with broadened and enhanced absorption in the UV spectral region, and outstanding wavelength-tunable laser action within the green-to-red spectral region (∼520-680 nm). These laser dyes allow the generation of a valuable tunable UV (∼260-350 nm) laser source by frequency doubling, which is essential to study accurately the photochemistry of biological molecules under solar irradiation. The tunability is achieved by selecting the substitution pattern of the hybrid. Key factors are the linking heteroatom (nitrogen vs. oxygen), the number of coumarin units joined to the BODIPY framework and the involved linking positions.

Vernier effect-based multiplication of the Sagnac beating frequency in ring laser gyroscope sensors

Science.gov (United States)

Adib, George A.; Sabry, Yasser M.; Khalil, Diaa

2018-02-01

A multiplication method of the Sagnac effect scale factor in ring laser gyroscopes is presented based on the Vernier effect of a dual-coupler passive ring resonator coupled to the active ring. The multiplication occurs when the two rings have comparable lengths or integer multiples and their scale factors have opposite signs. In this case, and when the rings have similar areas, the scale factor is multiplied by ratio of their length to their length difference. The scale factor of the presented configuration is derived analytically and the lock-in effect is analyzed. The principle is demonstrated using optical fiber rings and semiconductor optical amplifier as gain medium. A scale factor multiplication by about 175 is experimentally measured, demonstrating larger than two orders of magnitude enhancement in the Sagnac effect scale factor for the first time in literature, up to the authors' knowledge.

Flexible dye-sensitized solar cell fabricated on plastic substrate by laser-detachment and press method

International Nuclear Information System (INIS)

Kim, Choonghoe; Kim, Seongsu; Lee, Myeongkyu

2013-01-01

This report shows that flexible dye-sensitized solar cell can be fabricated by a laser-detachment and press method where the TiO 2 electrode typically sintered on glass source substrate is detached by a laser pulse and then is firmly adhered to the conductive plastic substrate by applying a high pressure. The cells fabricated by this process exhibited 36–43% smaller photocurrent and efficiency than the conventional glass cells with directly coated TiO 2 electrodes. It was attributed to the lowered dye coverage and electron diffusion length, both of which originate from the press-induced reduction of TiO 2 porosity. A maximum efficiency of 5.68% was obtained for the plastic cell. Bending of the electrode led to 20% loss of the current density and efficiency. However, no further performance degradation was observed even when the bending cycle was increased to 100, 300, and 500 times. This indicates that the bending-induced degradation of TiO 2 electrode on the plastic substrate takes place at the first bending.

Storage ring free electron lasers and saw-tooth instability

CERN Document Server

Dattoli, Giuseppe; Migliorati, M; Palumbo, L; Renieri, A

1999-01-01

We show that Free Electron Lasers (FEL) operating with storage rings may counteract beam instabilities of the Saw Tooth (STI) type. We use a model based on a set of equations that couple those describing the FEL evolution to those accounting for the STI dynamics. The analysis provides a clear picture of the FEL-STI mutual feedback and clarifies the mechanisms of the instability inhibition. The reliability of the results is supported by a comparison with fully numerical codes.

Femtosecond study of laser dyes soluble in water: coumarins

International Nuclear Information System (INIS)

Cassara, Laurence

1996-01-01

Coumarins build up one of the great families of laser dyes, and this research thesis addresses the study of four water-soluble coumarins (ATC, DMATC, DATC, and CHOS) which are analogue to conventional coumarins (C120, C311, C1, and C102). These molecules are made water-soluble by substitution of the methyl group in position 4 by a polyether group. Mechanisms of deactivation are studied by means of time-resolved fluorescence and transient adsorption methods which allow the reaction dynamics of coumarins after light excitation to be studied. Several time scales, from femto- to nano-second, have been reached and allowed various processes to be studied: relaxation, solvation dynamics, solute orientation diffusion, process of deactivation of radiative and non-radiative relaxation in various solvents [fr

Photophysical properties, photodegradation characteristics, and lasing action for coumarin dye C540A in polymeric media

Science.gov (United States)

Jones, Guilford, II; Huang, Zhennian; Pacheco, Dennis P., Jr.; Russell, Jeffrey A.

2004-07-01

Tunable solid-state dye lasers operating in the blue-green spectral region are attractive for a variety of applications. An important consideration in assessing the viability of this technology is the service life of the gain medium, which is presently limited by dye photodegradation. In this study, solid polymeric samples consisting of the coumarin dye C540A in modified PMMA were subjected to controlled photodegradation tests. The excitation laser was a flashlamp-pumped dye laser operating at 440 nm with a pulse duration of 1 μs. A complementary set of data was obtained for dye in solution phase for comparison purposes. Photophysical properties of C540A in water solution of polymethacrylic acid (PMAA) have been investigated with a view to assess the suitability of the sequestering polymer (PMAA) as an effective additive to facilitate use of a water medium for highly efficient blue-green dye lasers. Lasing action of C540A in aqueous PMAA has been realized using flashlamp-pumped laser system, yielding excellent laser efficiencies superior to that achieved in ethanolic solutions with the same dye. Laser characterization of dye in media included measurement of laser threshold, slope efficiency, pulse duration and output wavelength.

Switchable dual-wavelength single-longitudinal-mode erbium fiber laser utilizing a dual-ring scheme with a saturable absorber

Science.gov (United States)

Yang, Zi-Qing; Huang, Tzu-Jung; Chang, Yao-Jen; Yeh, Chien-Hung; Chow, Chi-Wai; Chen, Jing-Heng; Chen, Kun-Huang

2018-06-01

In this work, we propose and demonstrate a switchable dual-wavelength erbium-doped fiber (EDF) ring laser with stable single-longitudinal-mode (SLM) output. Here, a dual-ring (DR) structure with an unpumped EDF of 2 m is designed to achieve SLM oscillation. Five fiber Bragg gratings (FBGs) are applied in the laser cavity serving as the reflective element to generate different dual-wavelength outputs. In the measurement, six sets of generated dual-wavelengths with various mode-spacing (Δλ) can be achieved via the five FBGs. Additionally, the stability performance of the proposed EDF DR laser is also demonstrated.

Single-frequency blue light generation by single-pass sum-frequency generation in a coupled ring cavity tapered laser

DEFF Research Database (Denmark)

Jensen, Ole Bjarlin; Petersen, Paul Michael

2013-01-01

A generic approach for generation of tunable single frequency light is presented. 340 mW of near diffraction limited, single-frequency, and tunable blue light around 459 nm is generated by sum-frequency generation (SFG) between two tunable tapered diode lasers. One diode laser is operated in a ring...... cavity and another tapered diode laser is single-passed through a nonlinear crystal which is contained in the coupled ring cavity. Using this method, the single-pass conversion efficiency is more than 25%. In contrast to SFG in an external cavity, the system is entirely self-stabilized with no electronic...

Superradiant properties of 4,4'-bis(1¤H¤-phenanthro[9,10-¤d¤]imidazol-2-yl)biphenyl and how a laser dye with exceptional stability can be obtained in only one synthetic step

DEFF Research Database (Denmark)

Krebs, Frederik C; Lindvold, Lars René; Jørgensen, M.

2001-01-01

The extremely facile synthesis of a very stable laser dye with superradiant properties is reported. The laser action of the dye is demonstrated through a transverse pumping scheme with the advantage that no elaborate laser resonator is required due to the very high gain of the laser medium...

Present status of the NIJI-IV storage-ring free-electron lasers

Energy Technology Data Exchange (ETDEWEB)

Yamazaki, T.; Yamada, K.; Sei, N. [Electrotechnical Lab., Ibaraki (Japan)] [and others

1995-12-31

The tunable region of the free-electron-laser (FEL) wavelength with the NIJI-IV system is now 348{approximately}595 nm. After the lasing at 352 nm in 1994, the quality of the electron beam stored in the ring has been improved further, and the highest peak intensity of the laser obtained so far is more than 300 times as high as that of the resonated spontaneous emission. The macro-temporal structure of the lasing has been greatly improved. Recently, a single-bunch injection system was completed, and the system has been installed in the injector linac, which is expected to increase the peak stored-beam current. The commissioning and the test of the new system is under way. The beam transporting system from the linac to the ring is also being modified by increasing the number of quadrupole magnets. The experiments related to the FEL in the ultraviolet wavelength region will be begun in this coming May. The results and the status of the FEL experiments will be presented at the Conference.

Enhanced transduction of photonic crystal dye lasers for gas sensing via swelling polymer film

DEFF Research Database (Denmark)

Smith, Cameron; Lind, Johan Ulrik; Christiansen, Mads Brøkner

2011-01-01

We present the enhanced transduction of a photonic crystal dye laser for gas sensing via deposition of an additional swelling polymer film. Device operation involves swelling of the polymer film during exposure to specific gases, leading to a change in total effective refractive index. Experimental...... in its application to other intracavity-based detection schemes to enable gas sensing. © 2011 Optical Society of America....

Laser-induced incandescence of suspended particles as a source of excitation of dye luminescence

CERN Document Server

Zelensky, S

2003-01-01

The interaction of pulsed YAG-Nd sup 3 sup + laser radiation with submicron light-absorbing particles suspended in an aqueous solution of Rhodamine 6G is investigated experimentally. The experiments demonstrate that the laser-induced incandescence of suspended particles excites the luminescence of the dissolved dye molecules. The mechanism of the luminescence excitation consists in the reabsorption of the thermal radiation within the volume of the sample cell. On the ground of this mechanism of excitation, a method of measurement of the luminescence quantum yield is proposed and realized. The method requires the knowledge of the geometrical parameters of the cell and does not require the use of reference samples.

Variable diameter CO2 laser ring-cutting system adapted to a zoom microscope for applications on polymer tapes.

Science.gov (United States)

Förster, Erik; Bohnert, Patrick; Kraus, Matthias; Kilper, Roland; Müller, Ute; Buchmann, Martin; Brunner, Robert

2016-11-20

This paper presents the conception and implementation of a variable diameter ring-cutting system for a CO2 laser with a working wavelength of 10.6 μm. The laser-cutting system is adapted to an observation zoom microscope for combined use and is applicable for the extraction of small circular areas from polymer films, such as forensic adhesive tapes in a single shot. As an important characteristic for our application, the variable diameter ring-cutting system provides telecentricity in the target area. Ring diameters are continuously tunable between 500 μm and 2 mm. A minimum width of less than 20 μm was found for the ring profile edge. The basic characteristics of the system, including telecentricity, were experimentally evaluated and demonstrated by cutting experiments on different polymer tapes and further exemplary samples.

Investigation of longitudinal dynamic in laser electron storage ring

Energy Technology Data Exchange (ETDEWEB)

Karnaukhov, I.; Zelinsky, A. E-mail: zelinsky@kipt.kharkov.ua; Telegin, Yu

2001-09-01

Longitudinal dynamic of electron beam due to radiation damping and quantum fluctuations in the storage ring with a laser-electron interaction section (Compton scattering) is investigated. This investigation was carried out by numerical simulations using the Monte Carlo method. The dependence of the steady-state energy spread of electron beam due to the Compton back scattering of photons on the electron beam energy and photon flash density were obtained. Simulation findings are compared with the analytical estimations by Z. Huang.

Investigation of longitudinal dynamic in laser electron storage ring

CERN Document Server

Karnaukhov, I; Telegin, Yu P

2001-01-01

Longitudinal dynamic of electron beam due to radiation damping and quantum fluctuations in the storage ring with a laser-electron interaction section (Compton scattering) is investigated. This investigation was carried out by numerical simulations using the Monte Carlo method. The dependence of the steady-state energy spread of electron beam due to the Compton back scattering of photons on the electron beam energy and photon flash density were obtained. Simulation findings are compared with the analytical estimations by Z. Huang.

Preliminary results with sutured colonic anastomoses reinforced with dye-enhanced fibrinogen and a diode laser

Science.gov (United States)

Libutti, Steven K.; Williams, Matthew R.; Oz, Mehmet C.; Forde, Kenneth A.; Bass, Lawrence S.; Weinstein, Samuel; Auteri, Joseph S.; Treat, Michael R.; Nowygrod, Roman

1991-07-01

A common cause of morbidity in patients recovering from bowel surgery is leakage from colonic anastomoses. A technique utilizing a laser activated protein solder to strengthen colonic anastomoses in a canine model was evaluated. Following creation of six single-layer interrupted suture anastomoses in four dogs, a protein solder consisting of indocyanine green dye and fibrinogen was topically appied to the serosal surface and exposed to 808 nm continuous wave diode laser energy. Immediately following anastomosis, the mean leakage pressure of sutures alone was 129 +/- 14 mm hg (n equals 6), while the mean leakage pressure of sutures reinforced with the laser welded solder was 312 +/- 32 mm hg (n equals 6) (p anastomoses without causing appreciable thermal injury to surrounding tissues.

A dye laser with a partial-selective resonator

Energy Technology Data Exchange (ETDEWEB)

Makogon, M M; Sukhanov, V B

1977-04-01

The possibility of controlling the width and spectral position of the generation line of an organic dye laser (Rhodamine 6Zh) whose resonator represents a combination of selective and non-selective channels is demonstrated. The selective channel entails an unsymmetrically mounted prism with whose angular displacement the spectral width can be changed within broad ranges; the non-selective channel maintains the resonator's quality at a sufficiently high level. An expression is given which makes it possible to determine the generation's spectral width when fixing the prism's angular position. The change in the rearrangement band was studied in relation to the qualities of the selective and non-selective channels as determined by the form of the active medium's amplification contour (a narrowing of the spectrum from 0.15 to 0.0019 nm led to a reduction of the rearrangement area from 38.4 to 28.3 nm).

Rationalizing the photophysical properties of BODIPY laser dyes via aromaticity and electron-donor-based structural perturbations

Energy Technology Data Exchange (ETDEWEB)

Waddell, Paul G.; Liu, Xiaogang; Zhao, Teng; Cole, Jacqueline M.

2015-05-01

The absorption and fluorescence properties of six boron dipyrromethene (BODIPY) laser dyes with simple non-aromatic substituents are rationalized by relating them to observable structural perturbations within the molecules of the dyes. An empirical relationship involving the structure and the optical properties is derived using a combination of single-crystal X-ray diffraction data, quantum chemical calculations and electronic constants: i.e. the tendency of the pyrrole bond lengths towards aromaticity and the UV-vis absorption and fluorescence wavelengths correlating with the electron-donor properties of the substituents. The effect of molecular conformation on the solid-state optical properties of the dyes is also discussed. The findings in this study also demonstrate the usefulness and limitations of using crystal structure data to develop structure-property relationships in this class of optical materials, contributing to the growing effort to design optoelectronic materials with tunable properties via molecular engineering.

Surface-enhanced Raman spectroscopy on laser-engineered ruthenium dye-functionalized nanoporous gold

Science.gov (United States)

Schade, Lina; Franzka, Steffen; Biener, Monika; Biener, Jürgen; Hartmann, Nils

2016-06-01

Photothermal processing of nanoporous gold with a microfocused continuous-wave laser at λ = 532 nm provides a facile means in order engineer the pore and ligament size of nanoporous gold. In this report we take advantage of this approach in order to investigate the size-dependence of enhancement effects in surface-enhanced Raman spectroscopy (SERS). Surface structures with laterally varying pore sizes from 25 nm to ≥200 nm are characterized using scanning electron microscopy and then functionalized with N719, a commercial ruthenium complex, which is widely used in dye-sensitized solar cells. Raman spectroscopy reveals the characteristic spectral features of N719. Peak intensities strongly depend on the pore size. Highest intensities are observed on the native support, i.e. on nanoporous gold with pore sizes around 25 nm. These results demonstrate the particular perspectives of laser-fabricated nanoporous gold structures in fundamental SERS studies. In particular, it is emphasized that laser-engineered porous gold substrates represent a very well defined platform in order to study size-dependent effects with high reproducibility and precision and resolve conflicting results in previous studies.

Investigation of an He-Ne laser generating a beam with a ring-shaped intensity distribution

Energy Technology Data Exchange (ETDEWEB)

Sukhanov, I I; Troitskii, IU V; Iakushkin, S V

1987-02-01

The paper examines an He-Ne laser regime with the simultaneous generation of TEM(01) and TEM(10) modes, forming a beam with a ring-shaped intensity distribution with total suppression of the TEM(00) mode. The ratio of the intensity at the ring crest to the intensity at the axis reached a value of 200 and was limited by scattering in the optical components of the resonator. A regime of mutual frequency locking of the TEM(01) and TEM(10) modes was achieved with total spatial coherence of the ring-shaped beam. 14 references.

Infantile hemangioma: pulsed dye laser versus surgical therapy

Science.gov (United States)

Remlova, E.; Dostalova, T.; Michalusova, I.; Vranova, J.; Jelinkova, H.; Hubacek, M.

2014-05-01

Hemangioma is a mesenchymal benign tumor formed by blood vessels. Anomalies affect up to 10% of children and they are more common in females than in males. The aim of our study was to compare the treatment efficacy, namely the curative effect and adverse events, such as loss of pigment and appearance of scarring, between classical surgery techniques and laser techniques. For that reason a group of 223 patients with hemangioma was retrospectively reviewed. For treatment, a pulsed dye laser (PDL) (Rhodamine G, wavelength 595 nm, pulsewidth between 0.45 and 40 ms, spot diameter 7 mm, energy density 9-11 J cm-2) was used and the results were compared with a control group treated with classical surgical therapy under general anesthesia. The curative effects, mainly number of sessions, appearance of scars, loss of pigment, and relapses were evaluated as a marker of successful treatment. From the results it was evident that the therapeutic effects of both systems are similar. The PDL was successful in all cases. The surgery patients had four relapses. Classical surgery is directly connected with the presence of scars, but the system is safe for larger hemangiomas. It was confirmed that the PDL had the optimal curative effect without scars for small lesions (approximately 10 mm). Surgical treatment under general anesthesia is better for large hemangiomas; the disadvantage is the presence of scars.

A beamline for x-ray laser spectroscopy at the experimental storage ring at GSI

International Nuclear Information System (INIS)

Winters, D F A; Bagnoud, V; Ecker, B; Eisenbarth, U; Götte, S; Kuehl, Th; Stöhlker, Th; Zielbauer, B; Neumayer, P; Spielmann, C

2013-01-01

By combining an x-ray laser (XRL) with a heavy-ion storage ring, precision laser spectroscopy of the fine-structure splitting in heavy Li-like ions will be possible. An initial study has been performed to determine the feasibility of a first experiment at the experimental storage ring at GSI in Darmstadt, which also has great potential for the experiments planned for FAIR. We plan to perform a unique, direct and precise measurement of a fine-structure transition in a heavy Li-like ion. Such a measurement will test state-of-the-art atomic structure calculations in strong fields. This endeavour will require that the existing infrastructure is complemented by a dedicated beamline for the XRL. In this paper, we will discuss the details of this project and outline a proof-of-principle experiment. (paper)

Studies on the optogalvanic effect and isotope-selective excitation of ytterbium in a hollow cathode discharge lamp using a pulsed dye laser.

Science.gov (United States)

Kumar, Pankaj; Kumar, Jitendra; Prakash, Om; Saini, Vinod K; Dixit, Sudhir K; Nakhe, Shankar V

2013-09-01

This paper presents studies on the pulsed optogalvanic effect and isotope-selective excitation of Yb 555.648 nm (0 cm(-1) → 17 992.007 cm(-1)) and 581.067 nm (17 992.007 cm(-1) → 35 196.98 cm(-1)) transitions, in a Yb/Ne hollow cathode lamp. The Yb atoms were excited by narrow linewidth (500-1000 MHz) Rh110 and Rh6G dye based pulsed lasers. Optogalvanic signal inversion for ground state transition at 555.648 nm was observed beyond a hollow cathode discharge current of 8.5 mA, in contrast to normal optogalvanic signal at 581.067 nm up to maximum current of 14 mA. The isotope-selective excitation studies of Yb were carried out by recording Doppler limited optogalvanic signals as a function of dye laser wavelength. For the 581.067 nm transition, three even isotopes, (172)Yb, (174)Yb, and (176)Yb, and one odd isotope, (171)Yb, were clearly resolved. These data were compared with selective isotope excitation by 10 MHz linewidth continuous-wave dye laser. For 555.648 nm transition, isotopes were not clearly resolved, although isotope peaks of low modulation were observed.

Uniform silica nanoparticles encapsulating two-photon absorbing fluorescent dye

International Nuclear Information System (INIS)

Wu Weibing; Liu Chang; Wang Mingliang; Huang Wei; Zhou Shengrui; Jiang Wei; Sun Yueming; Cui Yiping; Xu Chunxinag

2009-01-01

We have prepared uniform silica nanoparticles (NPs) doped with a two-photon absorbing zwitterionic hemicyanine dye by reverse microemulsion method. Obvious solvatochromism on the absorption spectra of dye-doped NPs indicates that solvents can partly penetrate into the silica matrix and then affect the ground and excited state of dye molecules. For dye-doped NP suspensions, both one-photon and two-photon excited fluorescence are much stronger and recorded at shorter wavelength compared to those of free dye solutions with comparative overall dye concentration. This behavior is possibly attributed to the restricted twisted intramolecular charge transfer (TICT), which reduces fluorescence quenching when dye molecules are trapped in the silica matrix. Images from two-photon laser scanning fluorescence microscopy demonstrate that the dye-doped silica NPs can be actively uptaken by Hela cells with low cytotoxicity. - Graphical abstract: Water-soluble silica NPs doped with a two-photon absorbing zwitterionic hemicyanine dye were prepared. They were found of enhanced one-photon and two-photon excited fluorescence compared to free dye solutions. Images from two-photon laser scanning fluorescence microscopy demonstrate that the dye-doped silica NPs can be actively uptaken by Hela cells.

Modeling multipulsing transition in ring cavity lasers with proper orthogonal decomposition

International Nuclear Information System (INIS)

Ding, Edwin; Shlizerman, Eli; Kutz, J. Nathan

2010-01-01

A low-dimensional model is constructed via the proper orthogonal decomposition (POD) to characterize the multipulsing phenomenon in a ring cavity laser mode locked by a saturable absorber. The onset of the multipulsing transition is characterized by an oscillatory state (created by a Hopf bifurcation) that is then itself destabilized to a double-pulse configuration (by a fold bifurcation). A four-mode POD analysis, which uses the principal components, or singular value decomposition modes, of the mode-locked laser, provides a simple analytic framework for a complete characterization of the entire transition process and its associated bifurcations. These findings are in good agreement with the full governing equation.

Theoretical studies of solar-pumped lasers

Science.gov (United States)

Harries, W. L.

1983-01-01

Possible types of lasers were surveyed for solar power conversion. The types considered were (1) liquid dye lasers, (2) vapor dye lasers, and (3) nondissociative molecular lasers. These are discussed.

Laser synthesized super-hydrophobic conducting carbon with broccoli-type morphology as a counter-electrode for dye sensitized solar cells

Science.gov (United States)

Gokhale, Rohan; Agarkar, Shruti; Debgupta, Joyashish; Shinde, Deodatta; Lefez, Benoit; Banerjee, Abhik; Jog, Jyoti; More, Mahendra; Hannoyer, Beatrice; Ogale, Satishchandra

2012-10-01

A laser photochemical process is introduced to realize superhydrophobic conducting carbon coatings with broccoli-type hierarchical morphology for use as a metal-free counter electrode in a dye sensitized solar cell. The process involves pulsed excimer laser irradiation of a thin layer of liquid haloaromatic organic solvent o-dichlorobenzene (DCB). The coating reflects a carbon nanoparticle-self assembled and process-controlled morphology that yields solar to electric power conversion efficiency of 5.1% as opposed to 6.2% obtained with the conventional Pt-based electrode.A laser photochemical process is introduced to realize superhydrophobic conducting carbon coatings with broccoli-type hierarchical morphology for use as a metal-free counter electrode in a dye sensitized solar cell. The process involves pulsed excimer laser irradiation of a thin layer of liquid haloaromatic organic solvent o-dichlorobenzene (DCB). The coating reflects a carbon nanoparticle-self assembled and process-controlled morphology that yields solar to electric power conversion efficiency of 5.1% as opposed to 6.2% obtained with the conventional Pt-based electrode. Electronic supplementary information (ESI) available: Materials and equipment details, solar cell fabrication protocol, electrolyte spreading time measurement details, XPS spectra, electronic study, film adhesion test detailed analysis and field emission results. See DOI: 10.1039/c2nr32082g

Characterization of a 15 GHz integrated bulk InGaAsP passively modelocked ring laser at 1.53microm.

Science.gov (United States)

Barbarin, Yohan; Bente, Erwin A J M; Heck, Martijn J R; Oei, Y S; Nötzel, Richard; Smit, Meint K

2006-10-16

We report on an extensive characterization of a 15GHz integrated bulk InGaAsP passively modelocked ring laser at 1530 nm. The laser is modelocked for a wide range of amplifier currents and reverse bias voltages on the saturable absorber. We have measured a timing jitter of 7.1 ps (20 kHz - 80 MHz), which is low for an all-active device using bulk material and due to the ring configuration. Measured output pulses are highly chirped, a FWHM bandwidth is obtained of up to 4.5 nm. Such lasers with high bandwidth pulses and compatible with active-passive integration are of great interest for OCDMA applications.

Microscopic study on lasing characteristics of the UVSOR storage ring free electron laser

Energy Technology Data Exchange (ETDEWEB)

Hama, H. [Institute for Molecular Science, Okazaki (Japan)]|[Graduate Univ. for Advanced Stuides, Okazaki (Japan); Yamazaki, J.; Kinoshita, T. [Institute for Molecular Science, Okazaki (Japan)] [and others

1995-12-31

Characteristics of storage ring free electron laser (SRFEL) at a short wavelength region (UV and visible) has been studied at the UVSOR facility, Institute for Molecular Science. We have measured the laser power evolution by using a biplanar photodiode, and the micro-macro temporal structure of both the laser and the electron bunch with a dualsweep streak camera. The saturated energy of the laser micropulse in the gain-switching (Q-switching) mode has been measured as a function of the ring current. We have not observed a limitation of the output power yet within the beam current can be stored. We have analyzed the saturated micropulse energy based on a model of gain reduction due to the bunch-heating. The bunch-heating process seems to be very complicate. We derived time dependent gain variations from the shape of macropulse and the bunch length. Those two gain variations are almost consistent with each other but slightly different in detail. The gain may be not only simply reduced by the energy spread but also affected by the phase space rotation due to synchrotron oscillation of the electron bunch. As reported in previous issue, the lasing macropulse consists of a couple of micropulses that are simultaneously evolved. From high resolution two-dimensional spectra taken by the dual-sweep streak camera, we noticed considerable internal substructures of the laser micropulse in both the time distribution and the spectral shape. There are a couple of peaks separated with almost same distance in a optical bunch. Such substructure does not seem to result from statistical fluctuations of laser seeds. Although the origin of the substructure of macropulse is not dear at the present, we are going to discuss about SRFEL properties.

Storage ring free electron laser, pulse propagation effects and microwave type instabilities

Energy Technology Data Exchange (ETDEWEB)

Dattoli, G.; Mezi, L.; Renieri, A. [ENEA, Divisione Fisica Applicata, Centro Ricerche Frascati, Frascati, RM (Italy); Migliorati, M. [Rome Univ. La Sapienza, Rome (Italy). Dipt. di Energetica

2000-07-01

It has been developed a dynamical model accounting for the storage Ring Free Electron Laser evolution including pulse propagation effects and e-beam instabilities of microwave type. It has been analyzed the general conditions under which the on set of the laser may switch off the instability and focus everybody attention on the interplay between cavity mismatch, laser pulsed behavior and e-beam instability dynamics. Particular attention is also devoted to the laser operation in near threshold conditions, namely at an intracavity level just enough to counteract the instability, that show in this region new and interesting effects arises. [Italian] Si sviluppa un modello dinamico per la descrizione dell'evoluzione di un laser ad elettroni liberi in anello di accumulazione con l'inclusione di effetti di propagazione d'impulso e di instabilita' a microonda. Si analizzano le condizioni per le quali l'instaurarsi dell'operazione laser puo' spegnere l'instabilita' e si focalizza l'attenzione sulla connessione fra desincronismo della cavita', comportamento pulsato del laser e comportamento instabile del fascio di elettroni: si analizza in particolare l'operazione laser quando il guadagno e' prossimo alle perdite della cavita' e si osservano effetti particolarmente interessanti.

Photochemistry of triarylmethane dyes bound to proteins

Science.gov (United States)

Indig, Guilherme L.

1996-04-01

Triarylmethanes represent a class of cationic dyes whose potential as photosensitizers for use in photodynamic therapy of neoplastic diseases has never been comprehensively evaluated. Here, the laser-induced photodecomposition of three triarylmethane dyes, crystal violet, ethyl violet, and malachite green, non-covalently bound to bovine serum albumin (a model biological target) was investigated. Upon laser excitation at 532 nm, the bleaching of the corresponding dye-protein molecular complexes follows spectroscopic patterns that suggest the formation of reduced forms of the dyes as major reaction photoproducts. That implies that an electron or hydrogen atom transfer from the protein to the dye's moiety within the guest-host complex is the first step of the photobleaching process. Since the availability of dissolved molecular oxygen was not identified as a limiting factor for the phototransformations to occur, these dyes can be seen as potential phototherapeutic agents for use in hypoxic areas of tumors. These triarylmethane dyes strongly absorb at relatively long wavelengths (absorption maximum around 600 nm; (epsilon) max approximately equals 105 M-1 cm-1), and only minor changes in their absorption characteristics are observed upon binding to the protein. However the binding event leads to a remarkable increase in their fluorescence quantum yield and photoreactivity.

Absolute transition probabilities in the NeI 3p-3s fine structure by beam-gas-dye laser spectroscopy

International Nuclear Information System (INIS)

Hartmetz, P.; Schmoranzer, H.

1983-01-01

The beam-gas-dye laser two-step excitation technique is further developed and applied to the direct measurement of absolute atomic transition probabilities in the NeI 3p-3s fine-structure transition array with a maximum experimental error of 5%. (orig.)

Effect of the timing of treatment of port-wine stains with the flash-lamp-pumped pulsed-dye laser

NARCIS (Netherlands)

van der Horst, C. M.; Koster, P. H.; de Borgie, C. A.; Bossuyt, P. M.; van Gemert, M. J.

1998-01-01

BACKGROUND: Port-wine stains can be treated with a flash-lamp-pumped pulsed-dye laser, but it is uncertain whether this treatment is more effective if administered early in life, when the skin is thinner and the lesion is smaller. METHODS: We prospectively studied 100 patients with a previously

Optical spectroscopy of rubidium Rydberg atoms with a 297 nm frequency doubled dye laser

International Nuclear Information System (INIS)

Becker, Th.; Germann, Th.; Thoumany, P.; Stania, G.; Urbonas, L.; Haensch, T.

2008-01-01

Full text: Rydberg atoms have played an important role in atomic physics and optical spectroscopy since many years. Due to their long lifetime and the big dipole matrix element between neighbouring Rydberg levels they are an essential tool in microwave cavity-qed experiments. Ultracold Rydberg gases are a promising candidate for realizing controlled quantum gates in atomic ensembles. In most experiments Rydberg atoms are detected destructively, where the optically excited atoms are first ionized followed by an electronic detection of the ionization products. A Doppler-free purely optical detection was reported in a room temperature cell and in an atomic beam apparatus using the technique of electromagnetically induced transparency. In all these experiments the Rydberg atoms are excited with two lasers in a two-step ladder configuration. Here we show that Doppler-free purely optical spectroscopy is also possible with a one step excitation scheme involving a UV laser at 297 nm. We excite the 85 Rb isotope from the 5S 1/2 ground state to the 63P 3/2 state with a frequency doubled dye laser in a room temperature gas cell without buffer gas. Rydberg transitions are detected by monitoring the absorption of 780 nm laser light which is superimposed on the UV light and resonant with one hyperfine component of the Rubidium D2 line. With these two lasers we realize a V-scheme and utilize the quantum amplification effect due to the different natural lifetimes of the upper levels of the two transitions: an excitation into the 63P level hinders many absorption-emission cycles of the D2 transition and leads to a reduced absorption on that line. We discuss the shape of the observed spectra in the context of electron shelving and EIT experiments. By applying a frequency modulation to the UV laser, we can obtain dispersive signals which can be used to stabilize the laser to a specific Rydberg transition. By shifting the frequency of the 780 nm laser to crossover resonances in the

Plasma diagnosis by dye laser intracavity absorption: Final report for period January 1, 1982-May 31, 1986

International Nuclear Information System (INIS)

Brink, G.O.

1986-05-01

Dye laser intracavity absorption (ICA) has been studied as a potential diagnostic for plasma or neutral beam systems. For magnetic field measurements it is necessary to make Zeeman effect measurements on the resonance transition of atomic lithium on a millisecond time scale, or to make motional Stark Effect measurements on an injected fast atomic beam of hydrogen. To do this it may be necessary to sweep the dye laser in wavelength at a rapid rate so that the absorber can be sampled many times during the measurement. We have examined both of these possibilities during this contract. A rather detailed absorption spectrum of molecular hydrogen and deuterium arising in the 2c 3 Piu and other electronic states has been obtained and analyzed. This has provided new information on the types of molecular species that may be detected in a plasma by ICA, and may provide a basis for the application of ICA for the diagnosis of the edge plasma in a tokamak or in the end regions of a mirror machine

Synthesis and characterization of gold graphene composite with dyes as model substrates for decolorization: A surfactant free laser ablation approach

Science.gov (United States)

Sai Siddhardha, R. S.; Lakshman Kumar, V.; Kaniyoor, Adarsh; Sai Muthukumar, V.; Ramaprabhu, S.; Podila, Ramakrishna; Rao, A. M.; Ramamurthy, Sai Sathish

2014-12-01

A facile surfactant free laser ablation mediated synthesis (LAMS) of gold-graphene composite is reported here. The material was characterized using transmission electron microscopy, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, powdered X-ray diffraction, Raman spectroscopy, Zeta potential measurements and UV-Visible spectroscopic techniques. The as-synthesized gold-graphene composite was effectively utilized as catalyst for decolorization of 4 important textile and laser dyes. The integration of gold nanoparticles (AuNPs) with high surface area graphene has enhanced the catalytic activity of AuNPs. This enhanced activity is attributed to the synergistic interplay of pristine gold's electronic relay and π-π stacking of graphene with the dyes. This is evident when the Rhodamine B (RB) reduction rate of the composite is nearly twice faster than that of commercial citrate capped AuNPs of similar size. In case of Methylene blue (MB) the rate of reduction is 17,000 times faster than uncatalyzed reaction. This synthetic method opens door to laser ablation based fabrication of metal catalysts on graphene for improved performance without the aid of linkers and surfactants.

TiO{sub 2} nanocrystals synthesized by laser pyrolysis for the up-scaling of efficient solid-state dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Melhem, Hussein; Boucharef, Mourad; Di Bin, Catherine; Ratier, Bernard; Boucle, Johann [XLIM UMR 6172 Universite de Limoges/CNRS, Limoges Cedex (France); Simon, Pardis; Leconte, Yann; Herlin-Boime, Nathalie [IRAMIS/SPAM/LFP, CEA-CNRS URA 2453, CEA Saclay, Gif sur Yvette (France); Beouch, Layla; Goubard, Fabrice [Laboratoire de Physico-Chimie des Polymeres et des Interfaces (LPPI), Federation Institut des Materiaux (FD 4122), Universite de Cergy-Pontoise (France)

2011-10-15

A crucial issue regarding emerging nanotechnologies remains the up-scaling of new functional nanostructured materials towards their implementation in high performance applications on a large scale. In this context, we demonstrate high efficiency solid-state dye-sensitized solar cells prepared from new porous TiO{sub 2} photoanodes based on laser pyrolysis nanocrystals. This strategy exploits a reduced number of processing steps as well as non-toxic chemical compounds to demonstrate highly porous TiO{sub 2} films. The possibility to easily tune the TiO{sub 2} nanocrystal physical properties allows us to demonstrate all solid-state dye-sensitized devices based on a commercial benchmark materials (organic indoline dye and molecular hole transporter) presenting state-of-the-art performance comparable with reference devices based on a commercial TiO{sub 2} paste. In particular, a drastic improvement in pore infiltration, which is found to balance a relatively lower surface area compared to the reference electrode, is evidenced using laser-synthesized nanocrystals resulting in an improved short-circuit current density under full sunlight. Transient photovoltage decay measurements suggest that charge recombination kinetics still limit device performance. However, the proposed strategy emphasizes the potentialities of the laser pyrolysis technique for up-scaling nanoporous TiO{sub 2} electrodes for various applications, especially for solar energy conversion. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Radiolysis of anthraquinone dyes in aqueous solutions

International Nuclear Information System (INIS)

Vysotskaya, N.A.; Bortun, L.N.; Ogurtsov, N.A.; Migdalovich, E.A.; Revina, A.A.; Volodko, V.V.; AN SSSR, Moscow. Inst. Ehlektrokhimii)

1986-01-01

The commercial anthraquinone dyes (Dark Blue, Light Blue, Green) in aqueous solutions were shown to be decoloured and degrade under the action of ionizing radiation. The degree of decolouration and degradation of aromatic rings was found to increase in presence of oxygen. Hydroxyl radicals were shown to play the key role in the degradation of the dyes under irradiation. The radiolysis intermediate products were studied using the pulse radiolysis technique. (author)

Self-diffraction and Z-scan studies in organic dye doped thin films

International Nuclear Information System (INIS)

Madhana Sundari, R.; Palanisamy, P.K.

2006-01-01

Self-diffraction in Acid Red 87 (eosin Y) dye doped thin films is studied using argon ion laser (514.5 nm). Growth of self-diffraction grating is monitored by measuring intensities of various diffraction orders. This study has resulted in the observation of phase variation between the contributing beams in any diffracted order. This change of phase is measured at various stages of grating formation. Due to self-phase modulation, circular concentric rings pattern is obtained in the far field. The observed fluctuation in this pattern may be due to the phase variation between the contributing beams in any diffracted order. Z-scan technique is used to study the optical non-linearity of the sample

Electron beam properties and impedance characterization for storage rings used for free electron lasers

International Nuclear Information System (INIS)

Dattoli, G.; Mezi, L.; Renieri, A.; Migliorati, M.; Walker, R.

2000-01-01

Good electron beam qualities and stability are the crucial features of Storage Rings dedicated to synchrotron radiation sources or to Free Electron Laser. Most of these characteristics depends on the coupling of the e-beam with the machine environment, which can be in turn modelled in terms of a characteristic impedance, whose absolute value and structure can be used to specify both the stability (longitudinal and transverse) of the beam and its qualities (energy spread, bunch length, peak current ...). In this paper are considered two specific examples of Storage Rings used for FEL operation and analyze their performances by means of semi analytical and numerical methods. The analysis is aimed at clarifying the dependence of beam energy spread and bunch length on beam current and at providing a set of parameters useful for the optimization of Free Electron Laser or synchrotron radiation sources [it

Laser spectroscopy with a cooler ring at the ESR (GSI) and the TSR (MPI Heidelberg)

International Nuclear Information System (INIS)

Kuehl, T.; Borneis, S.; Greten, G.; Marx, D.; Neumann, R.; Schroeder, S.; Grieser, R.; Hoog, I.; Huber, G.; Klaft, I.; Klein, R.; Merz, P.; Balykin, V.; Bock, M.; Ellert, C.; Forck, P.; Grieser, M.; Grimm, R.; Habs, D.; Miesner, H.J.; Petrich, W.; Wanner, B.; Becker, C.; Schwalm, D.; Wolf, A.

1992-01-01

At the TSR cooler ring at Heidelberg, laser studies were carried out using singly charged lithium and beryllium ions. Laser spectroscopy of relativistic lithium ions (υ = 0.04c) yielded signals with a narrow linewidth, suitable for an experimental test of special relativity. A dramatic reduction of the beam temperature, as defined by the longitudinal velocity spread, was achieved via laser cooling in both cases. At the ion energies available at ESR it will become possible to prepare and store bare ions up to U 92+ . Electron cooling was successfully demonstrated for hydrogen-like Bi 82+ ions, where a laser experiment is scheduled to study the ground-state hyperfine splitting. (orig.)

[Alternatives to femtosecond laser technology: subnanosecond UV pulse and ring foci for creation of LASIK flaps].

Science.gov (United States)

Vogel, A; Freidank, S; Linz, N

2014-06-01

In refractive corneal surgery femtosecond (fs) lasers are used for creating LASIK flaps, dissecting lenticules and for astigmatism correction by limbal incisions. Femtosecond laser systems are complex and expensive and cutting precision is compromised by the large focal length associated with the commonly used infrared (IR) wavelengths. Based on investigations of the cutting dynamics, novel approaches for corneal dissection using ultraviolet A (UVA) picosecond (ps) pulses and ring foci from vortex beams are presented. Laser-induced bubble formation in corneal stroma was investigated by high-speed photography at 1-50 million frames/s. Using Gaussian and vortex beams of UVA pulses with durations between 200 and 850 ps the laser energy needed for easy removal of flaps created in porcine corneas was determined and the quality of the cuts by scanning electron microscopy was documented. Cutting parameters for 850 ps are reported also for rabbit eyes. The UV-induced and mechanical stress were evaluated for Gaussian and vortex beams. The results show that UVA picosecond lasers provide better cutting precision than IR femtosecond lasers, with similar processing times. Cutting energy decreases by >50 % when the laser pulse duration is reduced to 200 ps. Vortex beams produce a short, donut-shaped focus allowing efficient and precise dissection along the corneal lamellae which results in a dramatic reduction of the absorbed energy needed for cutting and of mechanical side effects as well as in less bubble formation in the cutting plane. A combination of novel approaches for corneal dissection provides the option to replace femtosecond lasers by compact UVA microchip laser technology. Ring foci are also of interest for femtosecond laser surgery, especially for improved lenticule excision.

Characterisation of the light pulses of a cavity dumped dye laser pumped by a cw mode-locked and q-switched Nd:YAG laser

International Nuclear Information System (INIS)

Geist, P.; Heisel, F.; Martz, A.; Miehe, J.A.; Miller, R.J.D.

1984-01-01

The frequency doubled pulses (of 532 nm) obtained, with the help of a KTP crystal, from those delivered by either a continuous wave mode-locked (100 MHz) or mode-locked Q-switched (0-1 KHz) Nd: YAG laser, are analyzed by means of a streak camera, operating in synchroscan or triggered mode. In the step-by-step measurements the pulse stability, concerning form and amplitude, is shown. In addition, measurements effectuated with synchronously pumped and cavity dumped dye laser (Rhodamine 6G), controlled by a Pockels cell, allows the obtention of stable and reproducible single pulses of 30 ps duration, 10 μJ energy and 500Hz frequency [fr

Optical feedback in dfb quantum cascade laser for mid-infrared cavity ring-down spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Terabayashi, Ryohei, E-mail: terabayashi.ryouhei@h.mbox.nagoya-u.ac.jp; Sonnenschein, Volker, E-mail: volker@nagoya-u.jp; Tomita, Hideki, E-mail: tomita@nagoya-u.jp; Hayashi, Noriyoshi, E-mail: hayashi.noriyoshi@h.mbox.nagoya-u.ac.jp; Kato, Shusuke, E-mail: katou.shuusuke@f.mbox.nagoya-u.ac.jp; Jin, Lei, E-mail: kin@nuee.nagoya-u.ac.jp; Yamanaka, Masahito, E-mail: yamanaka@nuee.nagoya-u.ac.jp; Nishizawa, Norihiko, E-mail: nishizawa@nuee.nagoya-u.ac.jp [Nagoya University, Department of Quantum Engineering, Graduate School of Engineering (Japan); Sato, Atsushi, E-mail: atsushi.sato@sekisui.com; Nozawa, Kohei, E-mail: kohei.nozawa@sekisui.com; Hashizume, Kenta, E-mail: kenta.hashizume@sekisui.com; Oh-hara, Toshinari, E-mail: toshinari.ohara@sekisui.com [Sekisui Medical Co., Ltd., Drug Development Solutions Center (Japan); Iguchi, Tetsuo, E-mail: t-iguchi@nucl.nagoya-u.ac.jp [Nagoya University, Department of Quantum Engineering, Graduate School of Engineering (Japan)

2017-11-15

A simple external optical feedback system has been applied to a distributed feedback quantum cascade laser (DFB QCL) for cavity ring-down spectroscopy (CRDS) and a clear effect of feedback was observed. A long external feedback path length of up to 4m can decrease the QCL linewidth to around 50kHz, which is of the order of the transmission linewidth of our high finesse ring-down cavity. The power spectral density of the transmission signal from high finesse cavity reveals that the noise at frequencies above 20kHz is reduced dramatically.

Present status of storage ring free electron laser experiment at ETL

International Nuclear Information System (INIS)

Yamazaki, T.; Nakamura, T.; Tomimasu, T.; Sugiyama, S.; Noguchi, T.

1988-01-01

Outline is described of the present status of the ETL storage-ring free electron laser project. The structure and the performance of the ETL-type transverse optical klystron are given. A modification of the dispersive section has decreased the degradation of the shape of the spontaneous-emission spectrum due to energy spread of the electron beam. Relevant parameters of the stored beam are presented. Measurement of the optical-cavity loss is under way. (author)

Tunable laser applications

CERN Document Server

Duarte, FJ

2008-01-01

Introduction F. J. Duarte Spectroscopic Applications of Tunable Optical Parametric Oscillators B. J. Orr, R. T. White, and Y. He Solid-State Dye Lasers Costela, I. García-Moreno, and R. Sastre Tunable Lasers Based on Dye-Doped Polymer Gain Media Incorporating Homogeneous Distributions of Functional Nanoparticles F. J. Duarte and R. O. James Broadly Tunable External-Cavity Semiconductor Lasers F. J. Duarte Tunable Fiber Lasers T. M. Shay and F. J. Duarte Fiber Laser Overview and Medical Applications

Saturation of the laser-induced narrowband coherent synchrotron radiation process: Experimental observation at a storage ring

Science.gov (United States)

Hosaka, M.; Yamamoto, N.; Takashima, Y.; Szwaj, C.; Le Parquier, M.; Evain, C.; Bielawski, S.; Adachi, M.; Zen, H.; Tanikawa, T.; Kimura, S.; Katoh, M.; Shimada, M.; Takahashi, T.

2013-02-01

We study the efficiency limitation affecting laser-induced coherent synchrotron radiation (CSR) at high laser power. Experiments are made on the UVSOR-II storage ring in conditions of narrowband terahertz CSR emission. While, at moderate power, CSR power increases quadratically with laser power, a noticeable decrease in efficiency and eventually a decrease in CSR power is observed experimentally at high power. Details of the underlying process are analyzed numerically. As the saturation effect depends almost instantaneously on the laser intensity, the saturation occurs locally in longitudinal space. This has important consequences on the modulation pattern induced on the electron bunch.

Clean Photothermal Heating and Controlled Release From Near Infrared Dye Doped Nanoparticles Without Oxygen Photosensitization

Science.gov (United States)

Guha, Samit; Shaw, Scott K.; Spence, Graeme T.; Roland, Felicia M.; Smith, Bradley D.

2015-01-01

The photothermal heating and release properties of biocompatible organic nanoparticles, doped with a near-infrared croconaine (Croc) dye, were compared with analogous nanoparticles doped with the common near-infrared dyes ICG and IR780. Separate formulations of lipid-polymer-hybrid nanoparticles and liposomes, each containing Croc dye, absorbed strongly at 808 nm and generated clean laser-induced heating (no production of 1O2 and no photobleaching of the dye). In contrast, laser-induced heating of nanoparticles containing ICG or IR780 produced reactive 1O2 leading to bleaching of the dye and also decomposition of co-encapsulated payload such as the drug Doxorubicin. Croc dye was especially useful as a photothermal agent for laser controlled release of chemically sensitive payload from nanoparticles. Solution state experiments demonstrated repetitive fractional release of water soluble fluorescent dye from the interior of thermosensitive liposomes. Additional experiments used a focused laser beam to control leakage from immobilized liposomes with very high spatial and temporal precision. The results indicate that fractional photothermal leakage from nanoparticles doped with Croc dye is a promising method for a range of controlled release applications. PMID:26149326

LASERS, ACTIVE MEDIA: The aqueous-polyelectrolyte dye solution as an active laser medium

Science.gov (United States)

Akimov, A. I.; Saletskii, A. M.

2000-11-01

The spectral, luminescent, and lasing properties of aqueous solutions of a cationic dye rhodamine 6G with additions of anion polyelectrolytes — polyacrylic and polymethacrylic acids — are studied. It is found that the energy and spectral properties of lasing of these solutions depend on the ratio of concentrations of polyelectrolyte and molecules. It is also found that the lasing parameters of aqueous-polyelectrolyte dye solutions can be controlled by changing the structure of the molecular system. The variation in the structure of aqueous-polyelectrolyte dye solutions of rhodamine 6G resulted in an almost five-fold increase in the lasing efficiency compared to that in aqueous dye solutions.

Dynamic synchronisation regions of a ring laser with the use of a periodic support

International Nuclear Information System (INIS)

Kuryatov, V N; Sudakov, V F

2008-01-01

The method is proposed for calculating dynamic synchronisation regions of a ring laser with a periodic frequency support of a special type. The proposed algorithm in essence taking into account the special type of the support allows the search for minimal widths of regions when the support parameters change. The widths of the regions are calculated as an example for the case of the harmonic carrier modulation as a harmonic envelope (three-frequency support) and an envelope of the 'soft' meander type (multifrequency support). (lasers, active media)

Dependence of mis-alignment sensitivity of ring laser gyro cavity on cavity parameters

Energy Technology Data Exchange (ETDEWEB)

Sun Feng; Zhang Xi; Zhang Hongbo; Yang Changcheng, E-mail: sunok1234@sohu.com [Huazhong Institute of Electro-Optics - Wuhan National Lab for Optoelectronics, Wuhan, Hubei (China)

2011-02-01

The ring laser gyroscope (RLG), as a rotation sensor, has been widely used for navigation and guidance on vehicles and missiles. The environment of strong random-vibration and large acceleration may deteriorate the performance of the RLG due to the vibration-induced tilting of the mirrors. In this paper the RLG performance is theoretically analyzed and the parameters such as the beam diameter at the aperture, cavity mirror alignment sensitivities and power loss due to the mirror tilting are calculated. It is concluded that by carefully choosing the parameters, the significant loss in laser power can be avoided.

Theory of frequency synchronization in a ring laser

Energy Technology Data Exchange (ETDEWEB)

Radina, Tatiana V., E-mail: tatiana.radina@gmail.com

2015-09-25

The self-consistent problem of the frequency synchronization of counter-propagating waves in a ring laser is rigorously solved. An intrinsic nonlinear mechanism of the phase coupling between the waves is considered for the first time. This ineradicable coupling is provided by modulation of the population difference of the energy levels of the active medium atoms in the electromagnetic field of two counter-propagating waves. The theoretical limit for the range of phase locking between the counter-propagating waves is established. The general equation of phase synchronization is obtained from the solution of a self-consistent problem. The frequency-dependent boundaries of the synchronization band calculated in the framework of this approach show good agreement with experimental results published in the literature.

Argon laser phototherapy of human malignancies using rhodamine-123 as a new laser dye: The intracellular role of oxygen

International Nuclear Information System (INIS)

Castro, D.J.; Saxton, R.E.; Markley, J.; Foote, C.S.; Fetterman, H.R.; Castro, D.J.; Ward, P.H.

1990-01-01

Recent studies demonstrated that the cationic, mitochondrial-specific dye Rhodamine-123 (Rh-123), is an efficient tumor photosensitizer for Argon laser treatment of human cancer cells both in vitro and in tumors grown as xenografts in athymic mice. To demonstrate the photodynamic mechanism of action of this reaction, the intracellular role of oxygen and temperature changes in treated cells have to be defined. In the current study, a large panel of human tumor cell lines of diverse histologic origin were tested for in vitro sensitivity to Rh-123 and the Argon laser (514.5 nm) in oxygen, deuterium oxide (D2O), and nitrogen (N2) environment. Tumor cells in suspension were first sensitized to Rh-123 (1 or 20 micrograms/ml for 1 hour), cooled on ice to 4 degrees C, and then exposed to the Argon laser (delta T = 14 +/- 1 degree C). Cell proliferation measured by [3H]-thymidine uptake 24 hours after sensitization with Rh-123 and laser treatment was significantly decreased in tumor cells kept in oxygen and D2O atmospheres. No decrease in DNA synthesis was seen in Rh-123 and laser treated cells kept in an N2 environment. Control tumor cells treated with Rh-123 or the Argon laser separately did not show any decreased [3H]-thymidine uptake in oxygen, D2O or N2 environment. These results provide evidence of a photodynamic process since Rh-123 sensitization and Argon laser activation occur at nonthermal levels of energy and are oxygen dependent. The high effectiveness of this technique of photodynamic therapy with the Argon laser, and low toxicity of Rh-123 could make its clinical use very attractive for the treatment of superficial malignancies

Study and realisation of a femtosecond dye laser operating at different wavelengths. Ultrashort pulses compression and amplification; Etude et realisation d'un laser a colorant femtoseconde fonctionnant a differentes longueurs d'onde. Compression et amplification d'impulsions ultrabreves

Energy Technology Data Exchange (ETDEWEB)

Georges, Patrick

1989-12-21

We present the study and the realization of a passively mode-locked dye laser producing pulses shorter than 100 femto-seconds (10{sup -13} s). In a ring cavity with an amplifier medium (Rhodamine 60) and a saturable absorber (DODCI), a sequence of four prisms controls the group velocity dispersion and allows the generation of very short pulses. Then we have studied the production of femtosecond pulses at other wavelengths directly from the femtosecond dye laser. For the first rime, 60 fs pulses at 685 nm and pulses shorter than 50 fs between 775 nm and 800 nm have been produced by passive mode locking. These near infrared pulses have been used to study the absorption saturation kinetics in semiconductors multiple quantum wells GaAs/GaAlAs. We have observed a singular behavior of the laser operating at 685 nm and analyzed the produced pulses in terms of optical solitons. To perform time resolved spectroscopy with shortest pulses, we have studied a pulse compressor and a multipass amplifier to increase the pulses energy. Pulses of 20 fs and 10 micro-joules (peak power: 0.5 GW) have been obtained at low repetition rate (10 Hz) and pulses of 16 fs and 0.6 micro-joules pulses have been generated at high repetition rate (11 kHz) using a copper vapor laser. These pulses have been used to study the absorption saturation kinetics of an organic dye (the Malachite Green). (author) [French] Ce memoire presente l'etude et la realisation d'un laser a colorant a verrouillage de modes passif produisant des impulsions de 100 femtosecondes (10- 13 s). Dans une cavite en anneau contenant un milieu amplificateur (Rhodamine 60) et un absorbant saturable (DODCI), un systeme de prismes permettant de controler la dispersion de vitesse de groupe realise une mise en phase de toutes les frequences du spectre des impulsions. Nous avons ensuite etudie la possibilite de produire des impulsions femtosecondes a d'autres longueurs d'onde directement avec l'oscillateur. Des impulsions de 60 fs a

Synthesis of azo pyridone dyes

Directory of Open Access Journals (Sweden)

Mijin Dušan Ž.

2011-01-01

Full Text Available Over 50% of all colorants which are used nowdays are azo dyes and pigments, and among them arylazo pyridone dyes (and pigments have became of interest in last several decades due to the high molar extinction coefficient, and the medium to high light and wet fastness properties. They find application generally as disperse dyes. The importance of disperse dyes increased in the 1970s and 1980s due to the use of polyester and nylon as the main synthetic fibers. Also, disperse dyes were used rapidly since 1970 in inks for the heat-transfer printing of polyester. The main synthetic route for the preparation of azo dyes is coupling reaction between an aromatic diazo compound and a coupling component. Of all dyes manufactured, about 60% are produced by this reaction. Arylazo pyridone dyes can be prepared from pyridone moiety as a coupling component, where substituent can be on nitrogen, and diazonim salts which can be derived from different substituted anilines or other heterocyclic derivatives. In addition, arylazo dyes containing pyridone ring can be prepared from arylazo diketones or arylazo ketoesters (obtained by coupling β-diketones or β-ketoesters with diazonim salts by condensation with cyanoacetamide. Disazo dyes can be prepared by tetrazotizing a dianiline and coupling it with a pyridone or by diazotizing aniline and coupling it with a dipyridone. Trisazo dyes can be also prepared by diazotizing of aniline and coupling it with a tripyridone or by hexazotizing a trianiline and coupling it with a pyridone. The main goal of this paper is to give a brief review on the synthesis of arylazo pyridone dyes due to the lack of such reviews. In addition, some properties of arylazo pyridone dyes as light fastness and azo-hydrazon tautomerism are disccused.

Estimation of ground and excited state dipole moment of laser dyes C504T and C521T using solvatochromic shifts of absorption and fluorescence spectra.

Science.gov (United States)

Basavaraja, Jana; Suresh Kumar, H M; Inamdar, S R; Wari, M N

2016-02-05

The absorption and fluorescence spectra of laser dyes: coumarin 504T (C504T) and coumarin 521T (C521T) have been recorded at room temperature in a series of non-polar and polar solvents. The spectra of these dyes showed bathochromic shift with increasing in solvent polarity indicating the involvement of π→π⁎ transition. Kamlet-Taft and Catalan solvent parameters were used to analyze the effect of solvents on C504T and C521T molecules. The study reveals that both general solute-solvent interactions and specific interactions are operative in these two systems. The ground state dipole moment was estimated using Guggenheim's method and also by quantum mechanical calculations. The solvatochromic data were used to determine the excited state dipole moment (μ(e)). It is observed that dipole moment value of excited state (μ(e)) is higher than that of the ground state in both the laser dyes indicating that these dyes are more polar in nature in the excited state than in the ground state. Copyright © 2015. Published by Elsevier B.V.

Dye gain gold NW array of surface plasmon polariton waveguide

Directory of Open Access Journals (Sweden)

Jun Zhu

Full Text Available Plasmon lasers can support ultrasmall mode confinement and ultrafast dynamics with device feature sizes below the diffraction limit. At present in the single visible light frequency, the optical gain method of constraint SPP on metal nanowires structure reported less. We design the gold nanowire array structure, consisting of PMMA and R6G dye molecules as gain, by 488 nm pump in the middle of the nanowires position for wide range of light, use symmetry broken overcome that momentum does not match the photonic and SPP energy conversion. Theoretical analysis shows that dyes provide coherent optical feedback, resulting in nanowires face will observe laser properties of surface plasmons. Feature analysis: the incident light and pump joint strength is greater than the sum of strength which is the incident light, pump respectively. Under the effect of dye molecules gain effective, length of SPP transmission can increase 1 µm. The results achieved in a single optical frequency of stimulated radiation, application of dye optical gain can achieve continuous gain effect. This is for the future development of plasma amplifier and the wavelength laser. Keywords: SPP, Stimulated radiation, Gold nanowires array, Dye molecules

The electron beam dynamics simulation in the laser-electron storage ring involving compton and intrabeam scattering

International Nuclear Information System (INIS)

Gladkikh, P.I.; Telegin, Yu.N.; Karnaukhov, I.M.

2002-01-01

The feasibility of the development of intense X-ray sources based on Compton scattering in laser-electron storage rings is discussed. The results of the electron beam dynamics simulation involving Compton and intrabeam scattering are presented

The electron beam dynamics simulation in the laser-electron storage ring involving compton and intrabeam scattering

CERN Document Server

Gladkikh, P I; Karnaukhov, I M

2002-01-01

The feasibility of the development of intense X-ray sources based on Compton scattering in laser-electron storage rings is discussed. The results of the electron beam dynamics simulation involving Compton and intrabeam scattering are presented.

End-pumped Nd:YVO4 laser with reduced thermal lensing via the use of a ring-shaped pump beam.

Science.gov (United States)

Lin, Di; Andrew Clarkson, W

2017-08-01

A simple approach for alleviating thermal lensing in end-pumped solid-state lasers using a pump beam with a ring-shaped intensity distribution to decrease the radial temperature gradient is described. This scheme has been implemented in a diode-end-pumped Nd:YVO 4 laser yielding 14 W of TEM 00 output at 1.064 μm with a corresponding slope efficiency of 53% and a beam propagation factor (M 2 ) of 1.08 limited by available pump power. By comparison, the same laser design with a conventional quasi-top-hat pump beam profile of approximately equal radial extent yielded only 9 W of output before the power rolled over due to thermal lensing. Further investigation with the aid of a probe beam revealed that the thermal lens power was ∼30% smaller for the ring-shaped pump beam compared to the quasi-top-hat beam. The implications for further power scaling in end-pumped laser configurations are considered.

Novel organic dyes based on phenyl-substituted benzimidazole for dye sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Saltan, Gözde Murat [Department of Chemistry, Faculty of Arts and Science, Celal Bayar University, Yunus Emre, 45140 Manisa (Turkey); Dinçalp, Haluk, E-mail: haluk.dincalp@cbu.edu.tr [Department of Chemistry, Faculty of Arts and Science, Celal Bayar University, Yunus Emre, 45140 Manisa (Turkey); Kıran, Merve; Zafer, Ceylan [Solar Energy Institute, Ege University, Bornova, 35100 Izmir (Turkey); Erbaş, Seçil Çelik [Celal Bayar University, Materials Engineering Department, Faculty of Engineering, Yunus Emre, 45140 Manisa (Turkey)

2015-08-01

Two new sensitizers derived from benzimidazole core for dye-sensitized solar cell (DSSC) applications were designed and synthesized as D–π–A structures, in which two phenyl-substituted benzimidazole group, a phenyl ring and a cyanoacrylic acid were used as the electron donor, π-conjugated linkage and the electron acceptor, respectively. Effect of methoxy- and N,N-dimetylamino- moieties attached to the phenyl groups of benzimidazole were investigated by means of optical and photovoltaic measurements. The compounds exhibit broad absorption maximum at 387 nm with the tail extending up to 500 nm on TiO{sub 2}-coated thin film. The longer wavelength absorption band around 360 nm and the much longer decay components could be attributed to the existence of charge transfer state of the dyes in solutions. DSSC device fabricated by using methoxy substituted dye (BI5a) as a sensitizer shows much better incident photon-to-current conversion efficiency (IPCE) of 64% giving cell efficiency of 2.68%. - Graphical abstract: Display Omitted - Highlights: • Long decay times suggest the delayed fluorescence caused by the existence of ICT. • The best solar energy conversion efficiency was obtained for BI5a dye (2.68%). • More fluorescent BI5a dye gives higher photocurrent generation.

Novel organic dyes based on phenyl-substituted benzimidazole for dye sensitized solar cells

International Nuclear Information System (INIS)

Saltan, Gözde Murat; Dinçalp, Haluk; Kıran, Merve; Zafer, Ceylan; Erbaş, Seçil Çelik

2015-01-01

Two new sensitizers derived from benzimidazole core for dye-sensitized solar cell (DSSC) applications were designed and synthesized as D–π–A structures, in which two phenyl-substituted benzimidazole group, a phenyl ring and a cyanoacrylic acid were used as the electron donor, π-conjugated linkage and the electron acceptor, respectively. Effect of methoxy- and N,N-dimetylamino- moieties attached to the phenyl groups of benzimidazole were investigated by means of optical and photovoltaic measurements. The compounds exhibit broad absorption maximum at 387 nm with the tail extending up to 500 nm on TiO 2 -coated thin film. The longer wavelength absorption band around 360 nm and the much longer decay components could be attributed to the existence of charge transfer state of the dyes in solutions. DSSC device fabricated by using methoxy substituted dye (BI5a) as a sensitizer shows much better incident photon-to-current conversion efficiency (IPCE) of 64% giving cell efficiency of 2.68%. - Graphical abstract: Display Omitted - Highlights: • Long decay times suggest the delayed fluorescence caused by the existence of ICT. • The best solar energy conversion efficiency was obtained for BI5a dye (2.68%). • More fluorescent BI5a dye gives higher photocurrent generation

From Storage Rings to Free Electron Lasers for Hard X-Rays

International Nuclear Information System (INIS)

Nuhn, H

2004-01-01

The intensity of X-ray sources has increased at a rapid rate since the late 1960s by 10 orders of magnitude and more through the use of synchrotron radiation produced by bending magnets, wigglers and undulators. Three generations of radiation sources have been identified depending on amplitude and quality of the radiation provided. While user facilities of the third generation were being constructed a new concept of radiation generating devices was being developed that offers an even larger increase in peak and average brightness than had been achieved till then. The new concept of the X-ray Free Electron Laser based on the principle of Self-Amplified Spontaneous Emission will be the basis of fourth generation X-ray source user facilities of this century. The paper will start with a brief history of the development of x-ray sources, discuss some of the differences between storage ring and free electron laser based approaches, and close with an update of the present development of x-ray free electron laser user facilities

From Storage Rings to Free Electron Lasers for Hard X-Rays

Energy Technology Data Exchange (ETDEWEB)

Nuhn, H

2004-01-09

The intensity of X-ray sources has increased at a rapid rate since the late 1960s by 10 orders of magnitude and more through the use of synchrotron radiation produced by bending magnets, wigglers and undulators. Three generations of radiation sources have been identified depending on amplitude and quality of the radiation provided. While user facilities of the third generation were being constructed a new concept of radiation generating devices was being developed that offers an even larger increase in peak and average brightness than had been achieved till then. The new concept of the X-ray Free Electron Laser based on the principle of Self-Amplified Spontaneous Emission will be the basis of fourth generation X-ray source user facilities of this century. The paper will start with a brief history of the development of x-ray sources, discuss some of the differences between storage ring and free electron laser based approaches, and close with an update of the present development of x-ray free electron laser user facilities.

From storage rings to free electron lasers for hard x-rays

International Nuclear Information System (INIS)

Nuhn, Heinz-Dieter

2004-01-01

The intensity of x-ray sources has increased at a rapid rate since the late 1960s by ten orders of magnitude and more through the use of synchrotron radiation produced by bending magnets, wigglers and undulators. Three generations of radiation sources have been identified depending on amplitude and quality of the radiation provided. While user facilities of the third generation were being constructed, a new concept of radiation generating devices was being developed that offers an even larger increase in peak and average brightness than had been achieved till then. The new concept of the x-ray free electron laser based on the principle of self-amplified spontaneous emission will be the basis of fourth generation x-ray source user facilities of this century. The paper will start with a brief history of the development of x-ray sources, it will then discuss some of the differences between storage ring and free electron laser based approaches, and will close with an update of the present development of x-ray free electron laser user facilities

Translational velocity oscillations of piston generated vortex rings

Science.gov (United States)

Kumar, Manoj; Arakeri, J. H.; Shankar, P. N.

1995-11-01

Experimental results are presented that show that the translational velocities of piston generated vortex rings often undergo oscillations, similar to those recently discovered for drop generated rings. An attempt has been made to minimize uncertainties by utilizing both dye and hydrogen bubbles for visualization and carefully repeating measurements on the same ring and on different realizations under the same nominal piston conditions. The results unambiguously show that under most conditions, both for laminar and turbulent rings and for rings generated from pipes and orifices, the oscillations are present. The present results, together with the earlier results on drop generated rings, give support to the view that translational velocity oscillations are probably an inherent feature of translating vortex ring fields.

Single frequency Nd:YLF and Nd:YVO4 laser in the red emission

International Nuclear Information System (INIS)

Camargo, Fabiola de Almeida

2010-01-01

All solid-state continuous-wave (cw) narrow emission linewidth and tunable red lasers are convenient alternative sources to bulky and expensive dye-lasers for high precision laser spectroscopy. Single-frequency operation of diode-pumped Nd:YLiF 4 and Nd:YVO 4 cw ring lasers were investigated in the 1.32 - 1.34μm range, together with their intracavity second-harmonic generation (SHG) to the red spectral range (0.65 - 0.67μm) using either BiB 3 O 6 (BiBO) or periodically-poled KTiOPO 4 (ppKTP) crystals. We report on such a single-end diode-pumped Nd:YVO 4 unidirectional red ring laser containing a type-I cut BiBO nonlinear crystal, yielding a record of 680 mW of single-longitudinal mode (SLM) red output power at 671.1nm without any intra-cavity etalon. For smooth SLM wavelength tuning over the full gain bandwidth (∼4 nm), a partially-coated (R = 40%) 100μm-thin etalon was found necessary, reducing the maximum SLM power (at 671.15 nm) to 380 mW. At 1342.5nm and with a T = 2% transmission output coupler, the laser provided an optimal 1.5W of single-frequency power. We demonstrate also optimal intracavity SHG of a Nd:YLF ring laser in the π- polarization (λ = 1321.5nm) using a ppKTP. The laser yielded 1.4 W of single frequency red power at 660.5 nm, as much as the maximum fundamental power that can be extracted from the resonator using an optimal output coupler. With a partially coated (R = 25%) thin etalon, the laser was tunable over Δλ∼ 1.6nm. (author)

Electronic-excitation energy transfer in heterogeneous dye solutions under laser excitation

International Nuclear Information System (INIS)

Levshin, L.V.; Mukushev, B.T.; Saletskii, A.M.

1995-01-01

An experimental study has been made of electronic-excitation energy transfer (EEET) among dye molecules of different types for different exciting-fight wavelengths and temperatures. Upon selective laser excitation of the donor, the inhomogeneous broadening of molecular levels increases the probability of EEET from the donor to acceptor molecules. The efficiency of this process is directly proportional to the acceptor molecule concentration and is temperature dependent. The EEET is accompanied by the spectral migration of energy among donor molecules, which reduces the fluorescence quantum efficiency of the donor. Increasing the frequency of the exciting light decreases in the donor fluorescence quantum efficiency. An increase in the acceptor molecule concentration results in a decrease of the spectral migration of excitation in the donor molecule system. 5 refs., 5 figs

Controllable continuous evolution of electronic states in a single quantum ring

Science.gov (United States)

Chakraborty, Tapash; Manaselyan, Aram; Barseghyan, Manuk; Laroze, David

2018-02-01

An intense terahertz laser field is shown to have a profound effect on the electronic and optical properties of quantum rings where the isotropic and anisotropic quantum rings can now be treated on equal footing. We have demonstrated that in isotropic quantum rings the laser field creates unusual Aharonov-Bohm oscillations that are usually expected in anisotropic rings. Furthermore, we have shown that intense laser fields can restore the isotropic physical properties in anisotropic quantum rings. In principle, all types of anisotropies (structural, effective masses, defects, etc.) can evolve as in isotropic rings in our present approach. Most importantly, we have found a continuous evolution of the energy spectra and intraband optical characteristics of structurally anisotropic quantum rings to those of isotropic rings in a controlled manner with the help of a laser field.

An All-Solid-State High Repetiton Rate Titanium:Sapphire Laser System For Resonance Ionization Laser Ion Sources

Science.gov (United States)

Mattolat, C.; Rothe, S.; Schwellnus, F.; Gottwald, T.; Raeder, S.; Wendt, K.

2009-03-01

On-line production facilities for radioactive isotopes nowadays heavily rely on resonance ionization laser ion sources due to their demonstrated unsurpassed efficiency and elemental selectivity. Powerful high repetition rate tunable pulsed dye or Ti:sapphire lasers can be used for this purpose. To counteract limitations of short pulse pump lasers, as needed for dye laser pumping, i.e. copper vapor lasers, which include high maintenance and nevertheless often only imperfect reliability, an all-solid-state Nd:YAG pumped Ti:sapphire laser system has been constructed. This could complement or even replace dye laser systems, eliminating their disadvantages but on the other hand introduce shortcomings on the side of the available wavelength range. Pros and cons of these developments will be discussed.

Fundamental characteristics of degradation-recoverable solid-state DFB polymer laser.

Science.gov (United States)

Yoshioka, Hiroaki; Yang, Yu; Watanabe, Hirofumi; Oki, Yuji

2012-02-13

A novel solid-state dye laser with degradation recovery was proposed and demonstrated. Polydimethylsiloxane was used as a nanoporous solid matrix to enable the internal circulation of dye molecules in the solid state. An internal circulation model for the dye molecules was also proposed and verified numerically by assuming molecular mobility and using a proposed diffusion equation. The durability of the laser was increased 20.5-fold compared with that of a conventional polymethylmethacrylate laser. This novel laser solves the low-durability problem of dye-doped polymer lasers.

Production of spectrally reconstructed uv-radiation by means of a nonlinear conversion of the generation frequency of a dye laser with lamp pumping

Energy Technology Data Exchange (ETDEWEB)

Anufrik, S S; Mostovnikov, V A; Rubinov, A N

1976-03-01

By doubling the generation frequency of an organic dye laser with lamp pumping, radiation is obtained in the spectral region of 285 to 305 nm. Depending on the mode of operation of a given laser the spectral width of the uv-radiation was 0.5 or approximately 0.003 nm. The maximum energy of second harmonic pulses was equal to approximately 0.01 J. (SJR)

Physical and chemical investigations on natural dyes

Science.gov (United States)

Acquaviva, S.; D'Anna, E.; de Giorgi, M. L.; Della Patria, A.; Baraldi, P.

2010-09-01

Natural dyes have been used extensively in the past for many purposes, such us to colour fibers and to produce inks, watercolours and paints, but their use declined rapidly after the discovery of synthetic colours. Nowadays we witness a renewed interest, as natural dyes are neither toxic nor polluting. In this work, physical and chemical properties of four selected dyes, namely red (Madder), yellow (Weld and Turmeric) and blue (Woad) colours, produced by means of traditional techniques at the Museo dei Colori Naturali (Lamoli, Italy), have been investigated. The chromatic properties have been studied through the reflectance spectroscopy, a non-invasive technique for the characterisation of chromaticity. Reflection spectra both from powders and egg-yolk tempera models have been acquired to provide the typical features of the dyes in the UV-vis spectral range. Moreover, to assess the feasibility of laser cleaning procedures, tempera layers were investigated after irradiation with an excimer laser. Micro Raman spectroscopy, Scanning Electron Microscopy and Energy Dispersive X-Ray analyses have complemented the survey, returning compositional and morphological information as well. Efforts have been made to give scientific feedback to the production processes and to support the research activity in the restoration of the artworks where these dyes were employed.

Fluorescence from gaseous UF/sub 6/ excited by a near-UV dye laser. [Decay time,quenching rate,room temperature

Energy Technology Data Exchange (ETDEWEB)

Benetti, P [Pavia Univ. (Italy); Cubeddu, R; Sacchi, C A; Svelto, O; Zaraga, F [Politecnico di Milano (Italy)

1976-06-01

Preliminary data are reported on the visible fluorescence of gaseous UF/sub 6/ excited by a dye laser at 374 nm. A decay time of 500 ns at p = 0 and a quenching rate of 5.7 x 10/sup -12/cm/sup 3/molec/sup -1/s/sup -1/ have been measured at room temperature.

VUV optical ring resonator for Duke storage ring free electron laser

Energy Technology Data Exchange (ETDEWEB)

Park, S.H.; Litvinenko, V.N.; Madey, J.M.J. [Duke Univ., Durham, NC (United States)] [and others

1995-12-31

The conceptual design of the multifaceted-mirror ring resonator for Duke storage ring VUV FEL is presented. The expected performance of the OK-4 FEL with ring resonator is described. We discuss in this paper our plans to study reflectivity of VUV mirrors and their resistivity to soft X-ray spontaneous radiation from OK-4 undulator.

Quasi-periodic synchronisation of self-modulation oscillations in a ring chip laser by an external periodic signal

International Nuclear Information System (INIS)

Aulova, T V; Kravtsov, Nikolai V; Lariontsev, E G; Chekina, S N

2011-01-01

The synchronisation of periodic self-modulation oscillations in a ring Nd:YAG chip laser under an external periodic signal modulating the pump power has been experimentally investigated. A new quasi-periodic regime of synchronisation of self-modulation oscillations is found. The characteristic features of the behaviour of spectral and temporal structures of synchronised quasi-periodic oscillations with a change in the external signal frequency are studied. (control of laser radiation parameters)

Ultraviolet laser ablation of fluorine-doped tin oxide thin films for dye-sensitized back-contact solar cells

Energy Technology Data Exchange (ETDEWEB)

Yang, Huan [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, 430074 (China); Fu, Dongchuan [ARC Centre of Excellence for Electromaterials Science, Department of Materials Engineering and School of Chemistry, Monash University, Clayton Victoria, 3800 (Australia); Jiang, Ming [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, 430074 (China); Duan, Jun, E-mail: duans@hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, 430074 (China); Zhang, Fei; Zeng, Xiaoyan [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, 430074 (China); Bach, Udo [ARC Centre of Excellence for Electromaterials Science, Department of Materials Engineering and School of Chemistry, Monash University, Clayton Victoria, 3800 (Australia)

2013-03-01

In this study, laser ablation of a fluorine-doped tin oxide (FTO) thin film on a glass substrate was conducted using a 355 nm Nd:YVO{sub 4} ultraviolet (UV) laser to obtain a 4 × 4 mm microstructure. The microstructure contains a symmetric set of interdigitated FTO finger electrodes of a monolithic back-contact dye-sensitized solar cell (BC-DSC) on a common substrate. The effects of UV laser ablation parameters (such as laser fluence, repetition frequency, and scanning speed) on the size precision and quality of the microstructure were investigated using a 4 × 4 orthogonal design and an assistant experimental design. The incident photon-to-electron conversion efficiency and the current–voltage characteristics of the BC-DSC base of the interdigitated FTO finger electrodes were also determined. The experimental results show that an FTO film microstructure with high precision and good quality can be produced on a glass substrate via laser ablation with high scanning speed, high repetition frequency, and appropriate laser fluence. - Highlights: ► The ablation width and depth generally depend on the laser fluence. ► The scanning speed and the repetition frequency must match each other. ► Slight ablation of the glass substrate can completely remove F-doped tin oxide.

Sum-Frequency-Generation-Based Laser Sidebands for Tunable Femtosecond Raman Spectroscopy in the Ultraviolet

Directory of Open Access Journals (Sweden)

Liangdong Zhu

2015-04-01

Full Text Available Femtosecond stimulated Raman spectroscopy (FSRS is an emerging molecular structural dynamics technique for functional materials characterization typically in the visible to near-IR range. To expand its applications we have developed a versatile FSRS setup in the ultraviolet region. We use the combination of a narrowband, ~400 nm Raman pump from a home-built second harmonic bandwidth compressor and a tunable broadband probe pulse from sum-frequency-generation-based cascaded four-wave mixing (SFG-CFWM laser sidebands in a thin BBO crystal. The ground state Raman spectrum of a laser dye Quinolon 390 in methanol that strongly absorbs at ~355 nm is systematically studied as a standard sample to provide previously unavailable spectroscopic characterization in the vibrational domain. Both the Stokes and anti-Stokes Raman spectra can be collected by selecting different orders of SFG-CFWM sidebands as the probe pulse. The stimulated Raman gain with the 402 nm Raman pump is >21 times larger than that with the 550 nm Raman pump when measured at the 1317 cm−1 peak for the aromatic ring deformation and ring-H rocking mode of the dye molecule, demonstrating that pre-resonance enhancement is effectively achieved in the unique UV-FSRS setup. This added tunability in the versatile and compact optical setup enables FSRS to better capture transient conformational snapshots of photosensitive molecules that absorb in the UV range.

Enhanced Photovoltaic Performances of Dye-Sensitized Solar Cells by Co-Sensitization of Benzothiadiazole and Squaraine-Based Dyes.

Science.gov (United States)

Islam, Ashraful; Akhtaruzzaman, Md; Chowdhury, Towhid H; Qin, Chuanjiang; Han, Liyuan; Bedja, Idriss M; Stalder, Romain; Schanze, Kirk S; Reynolds, John R

2016-02-01

Dye-sensitized solar cells (DSSCs) based on a donor-acceptor-donor oligothienylene dye containing benzothiadiazole (T4BTD-A) were cosensitized with dyes containing cis-configured squaraine rings (HSQ3 and HSQ4). The cosensitized dyes showed incident monochromatic photon-to-current conversion efficiency (IPCE) greater than 70% in the 300-850 nm wavelength region. The individual overall conversion efficiencies of the sensitizers T4BTD-A, HSQ3, and HSQ4 were 6.4%, 4.8%, and 5.8%, respectively. Improved power conversion efficiencies of 7.0% and 7.7% were observed when T4BTD-A was cosensitized with HSQ3 and HSQ4, respectively, thanks to a significant increase in current density (JSC) for the cosensitized DSSCs. Intensity-modulated photovoltage spectroscopy results showed a longer lifetime for cosensitized T4BTD-A+HSQ3 and T4BTD-A+HSQ4 compared to that of HSQ3 and HSQ4, respectively.

Detection of gain enhancement in laser-induced fluorescence of rhodamine B lasing dye by silicon dioxide nanostructures-coated cavity

Science.gov (United States)

Al-Tameemi, Mohammed N. A.

2018-03-01

In this work, nanostructured silicon dioxide films are deposited by closed-field unbalanced direct-current (DC) reactive magnetron sputtering technique on two sides of quartz cells containing rhodamine B dye dissolved in ethanol with 10‒5 M concentration as a random gain medium. The preparation conditions are optimized to prepare highly pure SiO2 nanostructures with a minimum particle size of about 20 nm. The effect of SiO2 films as external cavity for the random gain medium is determined by the laser-induced fluorescence of this medium, and an increase of about 200% in intensity is observed after the deposition of nanostructured SiO2 thin films on two sides of the dye cell.

Effects of early combinatorial treatment of autologous split-thickness skin grafts in red duroc pig model using pulsed dye laser and fractional CO2 laser.

Science.gov (United States)

Bailey, J Kevin; Blackstone, Britani N; DeBruler, Danielle M; Kim, Jayne Y; Baumann, Molly E; McFarland, Kevin L; Imeokparia, Folasade O; Supp, Dorothy M; Powell, Heather M

2018-01-01

The use of pulsed dye laser (PDL) and fractional CO 2 (FX CO 2 ) laser therapy to treat and/or prevent scarring following burn injury is becoming more widespread with a number of studies reporting reduction in scar erythema and pruritus following treatment with lasers. While the majority of studies report positive outcomes following PDL or FX CO 2 therapy, a number of studies have reported no benefit or worsening of the scar following treatment. The objective of this study was to directly compare the efficacy of PDL, FX CO 2 , and PDL + FX CO 2 laser therapy in reducing scarring post burn injury and autografting in a standardized animal model. Eight female red Duroc pigs (FRDP) received 4 standardized, 1 in. x 1 in. third degree burns that were excised and autografted. Wound sites were treated with PDL, FX CO 2 , or both at 4, 8, and 12 weeks post grafting. Grafts receiving no laser therapy served as controls. Scar appearance, morphology, size, and erythema were assessed and punch biopsies collected at weeks 4, 8, 12, and 16. At week 16, additional tissue was collected for biomechanical analyses and markers for inflammatory cytokines, extracellular matrix (ECM) proteins, re-epithelialization, pigmentation, and angiogenesis were quantified at all time points using qRT-PCR. Treatment with PDL, FX CO 2 , or PDL + FX CO 2 resulted in significantly less contraction versus skin graft only controls with no statistically significant difference among laser therapy groups. Scars treated with both PDL and FX CO 2 were visually more erythematous than other groups with a significant increase in redness between two and three standard deviations above normal skin redness. Scars treated with FX CO 2 were visually smoother and contained significantly fewer wrinkles. In addition, hyperpigmentation was significantly reduced in scars treated with FX CO 2 . The use of fractional carbon dioxide or pulsed dye laser therapy within 1 month of autografting significantly reduced scar

Synthesis and Optical Properties of Trioxatriangulenium Dyes with One and Two Peripheral Amino Substituents

DEFF Research Database (Denmark)

Sørensen, Thomas Just; Laursen, Bo Wegge

2010-01-01

-substituted triphenylmethylium (TPM) compounds by aromatic nucleophilic substitution with secondary amines and subsequent intramolecular ring closure. The optical properties of the new triangulenium dyes and their TPM precursors were investigated and compared to those of known TPM and xanthenium dyes. The optical properties...

Ring cavity for a Raman capillary waveguide amplifier

Science.gov (United States)

Kurnit, N.A.

1981-01-27

A regenerative ring amplifier and regenerative ring oscillator are described which function to feed back a portion of the Stokes signal to complete the ring cavity. The ring cavity configuration allows the CO/sub 2/ laser pump signal and Stokes signal to copropagate through the Raman capillary waveguide amplifier. A Raman capillary waveguide amplifier is also provided in the return leg of the ring cavity to increase gain without increasing the round trip time. Additionally, the ring cavity can be designed such that the amplified Stokes signal is synchronous with the mode-locked spikes of the incoming CO/sub 2/ laser pump signal.

Ring cavity for a Raman capillary waveguide amplifir

Science.gov (United States)

Kurnit, N.A.

1981-01-27

A regenerative ring amplifier and regenerative ring oscillator are described which function to feed back a portion of the Stokes signal to complete the ring cavity. The ring cavity configuration allows the CO/sub 2/ laser pump signal and Stokes signal to copropagate through the Raman capillary waveguide amplifier. A Raman capillary waveguide amplifier is also provided in the return leg of the ring cavity to increase gain without increasing the round trip time. Additionally, the ring cavity can be designed such that the amplified Stokes signal is synchronous with the mode-locked spikes of the incoming CO/sub 2/ laser pump signal.

Beam dynamics in Compton ring gamma sources

Directory of Open Access Journals (Sweden)

Eugene Bulyak

2006-09-01

Full Text Available Electron storage rings of GeV energy with laser pulse stacking cavities are promising intense sources of polarized hard photons which, via pair production, can be used to generate polarized positron beams. In this paper, the dynamics of electron bunches circulating in a storage ring and interacting with high-power laser pulses is studied both analytically and by simulation. Both the common features and the differences in the behavior of bunches interacting with an extremely high power laser pulse and with a moderate pulse are discussed. Also considerations on particular lattice designs for Compton gamma rings are presented.

''Stenungsund-77'': smoke plume measurements with a pulsed dye laser

Energy Technology Data Exchange (ETDEWEB)

Gustafsson, G; Hartmann, B; Spangstedt, G; Steinvall, O

1977-12-01

This report describes some of the results obtained in a field experiment at Stenungsund in May 1977, under the support and coordination of the Swedish Space Corporation. We made lidar measurements with a pulsed tunable dye laser working at wavelengths in the uv and visible part of the spectrum. The study concerned SO/sub 2/-absorption, NO/sub 2/-absorption, and particle scattering in the smoke plume of an oil fuel electric power plant. The SO/sub 2/-burden in the plume, near the smoke stack exit, as estimated from our lidar measurements, is compatible with in situ measurements and calculated values. The NO/sub 2/-concentration proved to be lower than the sensitivity limit of our lidar system. The particle scattering experiments led to qualitative results, and only permitted order of magnitude estimates of particle concentrations. They show, however, that a low power, eye safe uv lidar was capable of tracking plumes undiscernible to the eye, out to a distance of 2 to 3 km.

Generation of single-frequency tunable green light in a coupled ring tapered diode laser cavity

DEFF Research Database (Denmark)

Jensen, Ole Bjarlin; Petersen, Paul Michael

2013-01-01

in the broad wavelength range from 1049 nm to 1093 nm and the beam propagation factor is improved from M2 = 2.8 to below 1.1. The laser frequency is automatically locked to the cavity resonance frequency using optical feedback. Furthermore, we show that this adaptive external cavity approach leads to efficient......We report the realization of a tapered diode laser operated in a coupled ring cavity that significantly improves the coherence properties of the tapered laser and efficiently generates tunable light at the second harmonic frequency. The tapered diode laser is tunable with single-frequency output...... frequency doubling. More than 500 mW green output power is obtained by placing a periodically poled LiNbO3 crystal in the external cavity. The single frequency green output from the laser system is tunable in the 530 nm to 533 nm range limited by the LiNbO3 crystal. The optical to optical conversion...

Nonequilibrium statistical physics in a dithered ring laser gyroscope or quantum noise in pure and applied physics

International Nuclear Information System (INIS)

Schleich, W.; Dobiasch, P.

1986-01-01

A brief review is given of quantum noise in ring laser gyroscopes. Some the basic elements of ring laser theory, such as the Sagnac effect, the locking effect, and the influence of quantumnoise on the mean beat frequency versus rotation rate are discussed. The Langevin equation for the ase difference between the counterpropagating waves in the presence of any periodic and time symmetric dither is cast into a form which alows a qualitative discussion of the resulting lock-in curve as well as an exact expression in terms of infinite matrix continued fractions. The details of the transformation of the stochastic variable and the derivation of the exact expression for f>t may be found in appendices. Exact results are presented for two special cases of the dithering function: the harmonic and the square-wave bias

Application of quantum-dot multi-wavelength lasers and silicon photonic ring resonators to data-center optical interconnects

Science.gov (United States)

Beckett, Douglas J. S.; Hickey, Ryan; Logan, Dylan F.; Knights, Andrew P.; Chen, Rong; Cao, Bin; Wheeldon, Jeffery F.

2018-02-01

Quantum dot comb sources integrated with silicon photonic ring-resonator filters and modulators enable the realization of optical sub-components and modules for both inter- and intra-data-center applications. Low-noise, multi-wavelength, single-chip, laser sources, PAM4 modulation and direct detection allow a practical, scalable, architecture for applications beyond 400 Gb/s. Multi-wavelength, single-chip light sources are essential for reducing power dissipation, space and cost, while silicon photonic ring resonators offer high-performance with space and power efficiency.

INJECTION EFFICIENCY IN COMPTON RING NESTOR

Directory of Open Access Journals (Sweden)

P. I. Gladkikh

2017-12-01

Full Text Available NESTOR is the hard X-ray source that is under commissioning at NSC KIPT. NESTOR based on the Compton scattering of laser photons on relativistic electrons. The structure of the facility can be represented as the following components: a linear accelerator, a transport channel, a storage ring, and a laser-optical system. Electrons are stored in the storage ring for energy of 40-200 MeV. Inevitable alignment errors of magnetic elements are strongly effect on the beam dynamics in the storage ring. These errors lead to a shift of the equilibrium orbit relative to the ideal one. Significant shift of the equilibrium orbit could lead to loss of the beam on physical apertures. Transverse sizes of electron and laser beams are only few tens of microns at the interaction point. The shift of electron beam at the interaction point could greatly complicate the operation adjustment of storage ring without sufficient beam position diagnostic system. This article presents the simulation results of the efficiency of electron beam accumulation in the NESTOR storage ring. Also, this article is devoted to electron beam dynamics due to alignment errors of magnetic element in the ring.

Recent advance to 3 × 10(-5) rad near diffraction-limited beam divergence of dye laser with transverse-discharge flash-lamp pumping.

Science.gov (United States)

Trusov, K K

1994-02-20

A new experimental setup of a Rhodamine 6G dye laser with a transverse-discharge flash-lamp-pumping system is presented. It differs from a previous setup [Sov. J. Quantum Electron. 16, 468-471 (1989)] in that it has a larger laser beam aperture (32 mm) and higher pumping energy (1 kJ), which made it possible to test the scalability and reach near diffraction-limited laser beam divergence of 3 × 10(-5) rad FWHM at beam energy 1.4 J. The effect of spectral dispersion in the active medium and of other optical elements on the beam divergence is also discussed.

Enhancement of fluorescence, photo-physical parameters and laser performance of pyrromethene (PM597) laser dye by Ag nanoparticles in different media

Energy Technology Data Exchange (ETDEWEB)

Alhijry, Ibraheem A. [National Institute of Laser Enhanced Sciences, Cairo University, 12613 Giza (Egypt); Physics Department, Faculty of Science, Mansoura University, Mansoura (Egypt); Faculty of Education, Department of Physics, Hajjah University, Hajjah (Yemen); Gadallah, A.-S. [National Institute of Laser Enhanced Sciences, Cairo University, 12613 Giza (Egypt); Abdelkader, H.I. [Physics Department, Faculty of Science, Mansoura University, Mansoura (Egypt); Abou Kana, Maram T.H., E-mail: mabou202@niles.edu.eg [National Institute of Laser Enhanced Sciences, Cairo University, 12613 Giza (Egypt)

2016-03-15

The effect of surface plasmon resonance (SPR) of silver nanoparticles (Ag NPs), exposure to radiation, on the optical and photo-physical properties of pyrromethene (PM597) laser dye in liquid and solid media was assessed. 2-hydroxyethyl methacrylate was used as homo-monomer and homo-polymer, while 2-hydroxyethyl methacrylate / methyl methacrylate were used as co-monomer and co-polymer hosts. Ag NPs was prepared and confirmed its size by high resolution transmission electron microscope (HRTEM), UV/vis absorption spectroscopy and also, theoretically by using Mie theory. The molar concentration of prepared NPs was C=3.39×10{sup −9} mol/L. 40% C (1.356×10{sup −9} mol/L) Ag NPs was found to have the optimum distance with (1×10{sup −4} mol/L PM597 in liquid medium and 1×10{sup −3} mol/L PM597 in solid medium) dye molecules according to Metal Enhancement Fluorescence (MEF) model. [40% C Ag NPs: 1×10{sup −3} mol/L PM597] complex samples had 3.12 cm{sup −1} and 3.89 cm{sup −1} gain values in homo-and co-polymer media, while parent PM597 dye had 2.5 cm{sup −1} and 3.45 cm{sup −1} gain values. Also, amplified spontaneous emission (ASE) value of complex samples was 0.455% and 0.538% in case of homo- and co-polymer respectively. While it was 0.4% and 0.457% in case of parent PM597 dye in the same sequent media. Finally, photo-stabilities of complex samples had higher values in co-monomer and co-polymer hosts compared with respect to their stabilities in homo-monomer and homo-polymer hosts.

Enhancement of fluorescence, photo-physical parameters and laser performance of pyrromethene (PM597) laser dye by Ag nanoparticles in different media

International Nuclear Information System (INIS)

Alhijry, Ibraheem A.; Gadallah, A.-S.; Abdelkader, H.I.; Abou Kana, Maram T.H.

2016-01-01

The effect of surface plasmon resonance (SPR) of silver nanoparticles (Ag NPs), exposure to radiation, on the optical and photo-physical properties of pyrromethene (PM597) laser dye in liquid and solid media was assessed. 2-hydroxyethyl methacrylate was used as homo-monomer and homo-polymer, while 2-hydroxyethyl methacrylate / methyl methacrylate were used as co-monomer and co-polymer hosts. Ag NPs was prepared and confirmed its size by high resolution transmission electron microscope (HRTEM), UV/vis absorption spectroscopy and also, theoretically by using Mie theory. The molar concentration of prepared NPs was C=3.39×10 −9 mol/L. 40% C (1.356×10 −9 mol/L) Ag NPs was found to have the optimum distance with (1×10 −4 mol/L PM597 in liquid medium and 1×10 −3 mol/L PM597 in solid medium) dye molecules according to Metal Enhancement Fluorescence (MEF) model. [40% C Ag NPs: 1×10 −3 mol/L PM597] complex samples had 3.12 cm −1 and 3.89 cm −1 gain values in homo-and co-polymer media, while parent PM597 dye had 2.5 cm −1 and 3.45 cm −1 gain values. Also, amplified spontaneous emission (ASE) value of complex samples was 0.455% and 0.538% in case of homo- and co-polymer respectively. While it was 0.4% and 0.457% in case of parent PM597 dye in the same sequent media. Finally, photo-stabilities of complex samples had higher values in co-monomer and co-polymer hosts compared with respect to their stabilities in homo-monomer and homo-polymer hosts.

Strong-field physics using lasers and relativistic heavy ions at the high-energy storage ring HESR at FAIR

International Nuclear Information System (INIS)

Kuehl, T; Bagnoud, V; Stoehlker, T; Litvinov, Y; Winters, D F A; Zielbauer, B; Backe, H; Spielmann, Ch; Seres, J; Tünnermann, A; Neumayer, P; Aurand, B; Namba, S; Zhao, H Y

2014-01-01

The HESR high-energy ion storage ring at FAIR will provide unprecedented possibilities for strong-field physics using novel laser sources on relativistic heavy ions. An overview on the planning will be given.

Analysis of in vivo penetration of textile dyes causing allergic reactions

International Nuclear Information System (INIS)

Lademann, J; Patzelt, A; Worm, M; Richter, H; Sterry, W; Meinke, M

2009-01-01

Contact allergies to textile dyes are common and can cause severe eczema. In the present study, we investigated the penetration of a fluorescent textile dye, dissolved from a black pullover, into the skin of one volunteer during perspiration and nonperspiration. Previously, wearing this pullover had induced a severe contact dermatitis in an 82-year old woman, who was not aware of her sensitization to textile dyes. The investigations were carried out by in vivo laser scanning microscopy. It could be demonstrated that the dye was eluted from the textile material by sweat. Afterwards, the dye penetrated into the stratum corneum and into the hair follicles. Inside the hair follicles, the fluorescent signal was still detectable after 24 h, whereas it was not verifiable anymore in the stratum corneum, Laser scanning microscopy represents an efficient tool for in vivo investigation of the penetration and storage of topically applied substances and allergens into the human skin and reveals useful hints for the development and optimization of protection strategies

Fluorescence study of some xanthine dyes under stepped laser excitation

International Nuclear Information System (INIS)

Chirkova, L.V.; Ketsle, G.A.; Ermagambetov, K.T.

1996-01-01

Paper is devoted to definition of triplet state in molecules of xanthine dyes and study of intramolecular energy circulation. Stepped two-quanta excitation of dyes has been carried out with help of experimental unit. Intensive luminescence activated by excitation of triplet molecules of dyes within triplet-triplet band with wave length of 1060 nm was registered for eosin. Given luminescence spectrally coincides with fast fluorescence. 5 refs., 6 figs

High-power narrow-linewidth quasi-CW diode-pumped TEM00 1064 nm Nd:YAG ring laser.

Science.gov (United States)

Liu, Yuan; Wang, Bao-shan; Xie, Shi-yong; Bo, Yong; Wang, Peng-yuan; Zuo, Jun-wei; Xu, Yi-ting; Xu, Jia-lin; Peng, Qin-jun; Cui, Da-fu; Xu, Zu-yan

2012-04-01

We demonstrated a high average power, narrow-linewidth, quasi-CW diode-pumped Nd:YAG 1064 nm laser with near-diffraction-limited beam quality. A symmetrical three-mirror ring cavity with unidirectional operation elements and an etalon was employed to realize the narrow-linewidth laser output. Two highly efficient laser modules and a 90° quartz rotator for birefringence compensation were used for the high output power. The maximum average output power of 62.5 W with the beam quality factor M(2) of 1.15 was achieved under a pump power of 216 W at a repetition rate of 500 Hz, corresponding to the optical-to-optical conversion efficiency of 28.9%. The linewidth of the laser at the maximum output power was measured to be less than 0.2 GHz.

Controllable Continuous evolution of electronic states in a single quantum ring

OpenAIRE

Chakraborty, Tapash; Manaselyan, Aram; Barseghyan, Manuk; Laroze, David

2017-01-01

Intense terahertz laser field is shown to have a profound effect on the electronic and optical properties of quantum rings, where the isotropic and anisotropic quantum rings can now be treated on equal footing. We have demonstrated that in isotropic quantum rings the laser field creates irregular AB oscillations that are usually expected in anisotropic rings. Further, we have shown for the first time that intense laser fields can restore the {\\it isotropic} physical properties in anisotropic ...

Lasers for the SILVA laser isotope separation process

International Nuclear Information System (INIS)

Lapierre, Y.

1997-01-01

The main principles of the laser isotope separation process for the production of enriched uranium at lower cost, are reviewed and the corresponding optimal laser characteristics are described. The development of the SILVA laser isotope separation process involved researches in the various domains of pump lasers, dye lasers, laser and optics systems and two test facilities for the feasibility studies which are expected for 1997

Facile synthesis of silicon carbide-titanium dioxide semiconducting nanocomposite using pulsed laser ablation technique and its performance in photovoltaic dye sensitized solar cell and photocatalytic water purification

Energy Technology Data Exchange (ETDEWEB)

Gondal, M.A., E-mail: magondal@kfupm.edu.sa [Laser Research Group, Physics Department & Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Ilyas, A.M. [Laser Research Group, Physics Department & Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Baig, Umair [Laser Research Group, Physics Department & Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Center of Excellence for Scientific Research Collaboration with MIT, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)

2016-08-15

Highlights: • SiC–TiO{sub 2} semiconducting nanocomposites synthesized by nanosecond PLAL technique. • Synthesized nanocomposites were morphologically and optically characterized. • Nanocomposites were applied for the photocatalytic degradation of toxic organic dye. • Photovoltaic performance was investigated in dye sensitized solar cell. - Abstract: Separation of photo-generated charge carriers (electron and holes) is a major approach to improve the photovoltaic and photocatalytic performance of metal oxide semiconductors. For harsh environment like high temperature applications, ceramic like silicon carbide is very prominent. In this work, 10%, 20% and 40% by weight of pre-oxidized silicon carbide was coupled with titanium dioxide (TiO{sub 2}) to form nanocomposite semiconductor via elegant pulsed laser ablation in liquid technique using second harmonic 532 nm wavelength of neodymium-doped yttrium aluminium garnet (Nd-YAG) laser. In addition, the effect of silicon carbide concentration on the performance of silicon carbide-titanium dioxide nanocomposite as photo-anode in dye sensitized solar cell and as photocatalyst in photodegradation of methyl orange dye in water was also studied. The result obtained shows that photo-conversion efficiency of the dye sensitized solar cell was improved from 0.6% to 1.65% and the percentage of methyl orange dye removed was enhanced from 22% to 77% at 24 min under ultraviolet–visible solar spectrum in the nanocomposite with 10% weight of silicon carbide. This remarkable performance enhancement could be due to the improvement in electron transfer phenomenon by the presence of silicon carbide on titanium dioxide.

Comparison of various excitation and detection schemes for dye-doped polymeric whispering gallery mode micro-lasers.

Science.gov (United States)

Siegle, Tobias; Kellerer, Jonas; Bonenberger, Marielle; Krämmer, Sarah; Klusmann, Carolin; Müller, Marius; Kalt, Heinz

2018-02-05

We compare different excitation and collection configurations based on free-space optics and evanescently coupled tapered fibers for both lasing and fluorescence emission from dye-doped doped polymeric whispering gallery mode (WGM) micro-disk lasers. The focus of the comparison is on the lasing threshold and efficiency of light collection. With the aid of optical fibers, we localize the pump energy to the cavity-mode volume and reduce the necessary pump energy to achieve lasing by two orders of magnitude. When using fibers for detection, the collection efficiency is enhanced by four orders of magnitude compared to a free-space read-out perpendicular to the resonator plane. By enhancing the collection efficiency we are able to record a pronounced modulation of the dye fluorescence under continuous wave (cw) pumping conditions evoked by coupling to the WGMs. Alternatively to fibers as a collection tool, we present a read-out technique based on the detection of in-plane radiated light. We show that this method is especially beneficial in an aqueous environment as well as for size-reduced micro-lasers where radiation is strongly pronounced. Furthermore, we show that this technique allows for the assignment of transverse electric (TE) and transverse magnetic (TM) polarization to the observed fundamental modes in a water environment by performing polarization-dependent photoluminescence (PL) spectroscopy. We emphasize the importance of the polarization determination for sensing applications and verify expected differences in the bulk refractive index sensitivity for TE and TM WGMs experimentally.

Optical Fiber Sensors Based on Fiber Ring Laser Demodulation Technology.

Science.gov (United States)

Xie, Wen-Ge; Zhang, Ya-Nan; Wang, Peng-Zhao; Wang, Jian-Zhang

2018-02-08

A review for optical fiber sensors based on fiber ring laser (FRL) demodulation technology is presented. The review focuses on the principles, main structures, and the sensing performances of different kinds of optical fiber sensors based on FRLs. First of all, the theory background of the sensors has been discussed. Secondly, four different types of sensors are described and compared, which includes Mach-Zehnder interferometer (MZI) typed sensors, Fabry-Perot interferometer (FPI) typed sensors, Sagnac typed sensors, and fiber Bragg grating (FBG) typed sensors. Typical studies and main properties of each type of sensors are presented. Thirdly, a comparison of different types of sensors are made. Finally, the existing problems and future research directions are pointed out and analyzed.

Continuous wave room temperature external ring cavity quantum cascade laser

Energy Technology Data Exchange (ETDEWEB)

Revin, D. G., E-mail: d.revin@sheffield.ac.uk; Hemingway, M.; Vaitiekus, D.; Cockburn, J. W. [Physics and Astronomy Department, The University of Sheffield, S3 7RH Sheffield (United Kingdom); Hempler, N.; Maker, G. T.; Malcolm, G. P. A. [M Squared Lasers Ltd., G20 0SP Glasgow (United Kingdom)

2015-06-29

An external ring cavity quantum cascade laser operating at ∼5.2 μm wavelength in a continuous-wave regime at the temperature of 15 °C is demonstrated. Out-coupled continuous-wave optical powers of up to 23 mW are observed for light of one propagation direction with an estimated total intra-cavity optical power flux in excess of 340 mW. The uni-directional regime characterized by the intensity ratio of more than 60 for the light propagating in the opposite directions was achieved. A single emission peak wavelength tuning range of 90 cm{sup −1} is realized by the incorporation of a diffraction grating into the cavity.

Continuous wave room temperature external ring cavity quantum cascade laser

International Nuclear Information System (INIS)

Revin, D. G.; Hemingway, M.; Vaitiekus, D.; Cockburn, J. W.; Hempler, N.; Maker, G. T.; Malcolm, G. P. A.

2015-01-01

An external ring cavity quantum cascade laser operating at ∼5.2 μm wavelength in a continuous-wave regime at the temperature of 15 °C is demonstrated. Out-coupled continuous-wave optical powers of up to 23 mW are observed for light of one propagation direction with an estimated total intra-cavity optical power flux in excess of 340 mW. The uni-directional regime characterized by the intensity ratio of more than 60 for the light propagating in the opposite directions was achieved. A single emission peak wavelength tuning range of 90 cm −1 is realized by the incorporation of a diffraction grating into the cavity

Electric field detection of coherent synchrotron radiation in a storage ring generated using laser bunch slicing

International Nuclear Information System (INIS)

Katayama, I.; Shimosato, H.; Bito, M.; Furusawa, K.; Adachi, M.; Zen, H.; Kimura, S.; Katoh, M.; Shimada, M.; Yamamoto, N.; Hosaka, M.; Ashida, M.

2012-01-01

The electric field of coherent synchrotron radiation (CSR) generated by laser bunch slicing in a storage ring has been detected by an electro-optic sampling method. The gate pulses for sampling are sent through a large-mode-area photonic-crystal fiber. The observed electric field profile of the CSR is in good agreement with the spectrum of the CSR observed using Fourier transform far-infrared spectrometry, indicating good phase stability in the CSR. The longitudinal density profiles of electrons modulated by laser pulses were evaluated from the electric field profile.

Optical Analysis of Grazing Incidence Ring Resonators for Free-Electron Lasers

Science.gov (United States)

Gabardi, David Richard

1990-08-01

The design of resonators for free-electron lasers (FELs) which are to operate in the soft x-ray/vacuum ultraviolet (XUV) region of the spectrum is complicated by the fact that, in this wavelength regime, normal incidence mirrors, which would otherwise be used for the construction of the resonators, generally have insufficient reflectivities for this purpose. However, the use of grazing incidence mirrors in XUV resonators offers the possibility of (1) providing sufficient reflectivity, (2) a lessening of the mirrors' thermal loads due to the projection of the laser beam onto an oblique surface, and (3) the preservation of the FEL's tunability. In this work, the behavior of resonators employing grazing incidence mirrors in ring type configurations is explored. In particular, two designs, each utilizing four off-axis conic mirrors and a number of flats, are examined. In order to specify the location, orientation, and surface parameters for the mirrors in these resonators, a design algorithm has been developed based upon the properties of Gaussian beam propagation. Two computer simulation methods are used to perform a vacuum stability analysis of the two resonator designs. The first method uses paraxial ray trace techniques with the resonators' thin lens analogues while the second uses the diffraction-based computer simulation code GLAD (General Laser Analysis and Design). The effects of mirror tilts and deviations in the mirror surface parameters are investigated for a number of resonators designed to propagate laser beams of various Rayleigh ranges. It will be shown that resonator stability decreases as the laser wavelength for which the resonator was designed is made smaller. In addition, resonator stability will also be seen to decrease as the amount of magnification the laser beam receives as it travels around the resonator is increased.

Self-injection locking of the DFB laser through an external ring fiber cavity: Polarization behavior

Directory of Open Access Journals (Sweden)

J.L. Bueno Escobedo

Full Text Available We study stability of self-injection locking realized with DFB laser coupled with an external fiber optic ring cavity. Polarization behavior of the radiation circulating in the feedback loop is reported. Two regimes of mode hopping have been observed; one of them is accompanied by polarization bistability involving two orthogonal polarization states. Keywords: Self-injection locking, Polarization, Optical fiber

Digitally tunable dual wavelength emission from semiconductor ring lasers with filtered optical feedback

International Nuclear Information System (INIS)

Khoder, Mulham; Verschaffelt, Guy; Nguimdo, Romain Modeste; Danckaert, Jan; Leijtens, Xaveer; Bolk, Jeroen

2013-01-01

We report on a novel integrated approach to obtain dual wavelength emission from a semiconductor laser based on on-chip filtered optical feedback. Using this approach, we show experiments and numerical simulations of dual wavelength emission of a semiconductor ring laser. The filtered optical feedback is realized on-chip by employing two arrayed waveguide gratings to split/recombine light into different wavelength channels. Semiconductor optical amplifiers are placed in the feedback loop in order to control the feedback strength of each wavelength channel independently. By tuning the current injected into each of the amplifiers, we can effectively cancel the gain difference between the wavelength channels due to fabrication and material dichroism, thus resulting in stable dual wavelength emission. We also explore the accuracy needed in the operational parameters to maintain this dual wavelength emission. (letter)

Tunable single-polarization single-longitudinal-mode erbium-doped fiber ring laser employing a CMFBG filter and saturable absorber

Science.gov (United States)

Feng, Suchun; Lu, Shaohua; Peng, Wanjing; Li, Qi; Feng, Ting; Jian, Shuisheng

2013-04-01

A tunable single-polarization single-longitudinal-mode (SLM) erbium-doped fiber ring laser is proposed and demonstrated. For the first time as we know, a chirped moiré fiber Bragg grating (CMFBG) filter with ultra-narrow transmission band and a uniform fiber Bragg grating (UFBG) are used to select the laser longitudinal mode. The stable SLM operation of the fiber laser is guaranteed by the combination of the CMFBG filter and 3 m unpumped erbium-doped fiber acting as a saturable absorber. The single polarization operation of the fiber laser is obtained by using an inline broadband polarizer. A tuning range of about 0.7 nm with about 0.1 nm step is achieved by stretching the uniform FBG.

Water-vapor absorption line measurements in the 940-nm band by using a Raman-shifted dye laser

Science.gov (United States)

Chu, Zhiping; Wilkerson, Thomas D.; Singh, Upendra N.

1993-01-01

We report water-vapor absorption line measurements that are made by using the first Stokes radiation (930-982 nm) with HWHM 0.015/cm generated by a narrow-linewidth, tunable dye laser. Forty-five absorption line strengths are measured with an uncertainty of 6 percent and among them are fourteen strong lines that are compared with previous measurements for the assessment of spectral purity of the light source. Thirty air-broadened linewidths are measured with 8 percent uncertainty at ambient atmospheric pressure with an average of 0.101/cm. The lines are selected for the purpose of temperature-sensitive or temperature-insensitive lidar measurements. Results for these line strengths and linewidths are corrected for broadband radiation and finite laser linewidth broadening effects and compared with the high-resolution transmission molecular absorption.

Formation of ring-patterned nanoclusters by laser–plume interaction

International Nuclear Information System (INIS)

Sivayoganathan, Mugunthan; Tan Bo; Venkatakrishnan, Krishnan

2013-01-01

This article reports for the first time a unique study performed to regulate the ring diameter of nanoclusters fabricated during femtosecond laser ablation of solids and a mechanism is proposed for the formation of those ring clusters. The ring nanoclusters are made out of nanoparticles with a range of 10–30 nm. Our experimental studies showed the synthesis of ring nanoclusters with random diameter distribution on metals, nonmetals, and semiconductors, such as titanium, aluminum, glasses, ceramics, graphite, and silicon. To regulate the ring size, the effects of laser parameters, such as wavelength, pulse duration, pulse energy, and repetition rate on the ring diameter are analyzed. The influence of ablated materials and the background gas on ring size is also elaborated in this article. The motion of plume species under the influence of ponderomotive force on free electrons possibly played a key role in the formation of the ring-patterned nanoclusters. This study could help to understand the fundamentals in laser ablative nanosynthesis as well as to produce nanostructures with organized ring diameter that controls the density and porosity of those 3D nanostructures.

The Covalent Binding of Photosensitive Dyes to Monocrystalline Silicon Surface and Their Spectral Response

Institute of Scientific and Technical Information of China (English)

郭志新; 郝纪祥; 张祖训; 曹子祥

1993-01-01

A chemical method is proposed to bond photo-sensitive dyes directly to the surface of polished monocrystalline silicon. A methincyanine dye and a trimethincyanine dye have been bonded covalently onto silicon surface through Si—N bond, which are characterized by XPS technique and laser Raman spectra. Photovoltaic effect has been observed with the In/dye/n-Si sandwich devices composed of the dye-bonded n-Si wafers. Significant spectral response shows the characteristic absorptance maxima of the bonded dyes.

Computer-aided design and modeling of nickel dithiolene near-infrared dyes. 1998 summer research program for high school juniors at the University of Rochester's Laboratory for Laser Energetics. Student research reports

International Nuclear Information System (INIS)

Corsello, S.

1999-03-01

Recent advances in computational chemistry have made it feasible to design many types of molecules and predict their properties theoretically. The author applied these techniques to the design of organometallic transition-metal dyes absorbing in the near-infrared region of the spectrum which possess the combination of a large molar extinction coefficient, good chemical and thermal stability, and a high solubility in liquid crystal (LC) hosts. These properties are required for the dye to function as a near-infrared (IR) attenuator in a liquid crystal point diffraction interferometer (LCPDI) device that will be used as a beam diagnostic on the 60-beam OMEGA solid-state Nd:glass laser system at the University of Rochester's Laboratory for Laser Energetics. Using commercially available software, both the absorption spectra and solubility characteristics of bis[1,2-di-(p-n alkoxyphenyl)ethane-1,2-dithione] nickel dye complexes were modeled in an isotropic host (cyclohexane) and, in most cases, excellent agreement was found with experimental data. Two additional compounds utilizing the same nickel dithiolene core but with alkylthio and phenylalkylthio terminal groups have been designed and show excellent potential to produce dramatic improvements in both solubility and optical density (absorbance) in liquid crystalline hosts. Based upon my work, a new dye not previously reported, 2(C 4 S)2(C 4 SPh)DTNi, has been proposed to satisfy the LCPDI device requirements. The nickel dithiolene dyes may also find important applications in other technology areas such as near-IR photography and laser-based near-IR communications

Coherent x-rays and vacuum-ultraviolet radiation from storage-ring-based undulators and free electron lasers

International Nuclear Information System (INIS)

Kim, K.J.

1984-12-01

High-brightness electron storage rings and permanent-magnet technology provide a basis for the development of coherent radiation in the 10- to 1000-A (xuv) spectral range. The most assured route to the production of coherent x-rays and vuv is the simple interaction between properly constrained relativistic electrons and permanent-magnet undulators, a subject that is already well understood and where technology is well advanced. Other techniques are less well developed, but with increasing degrees of technical challenge they will provide additional coherence properties. Transverse optical klystrons (TOKs) provide an opportunity for additional coherence at certain harmonics of longer-wavelength lasers. Free electron lasers (FELs) extend coherence capabilities substantially through two possible routes: one is the development of suitable mirror coatings. Both FEL techniques would provide vuv radiation and soft x rays with extremely narrow spectral content. Research on all of these techniques (undulators, TOKs, and FELs) is possible in a single facility based on a high-brightness electron storage ring, referred to herein as a Coherent xuv Facility (CXF). Individual items from the report were prepared separately for the data base

Ring-shaped active mode-locked tunable laser using quantum-dot semiconductor optical amplifier

Science.gov (United States)

Zhang, Mingxiao; Wang, Yongjun; Liu, Xinyu

2018-03-01

In this paper, a lot of simulations has been done for ring-shaped active mode-locked lasers with quantum-dot semiconductor optical amplifier (QD-SOA). Based on the simulation model of QD-SOA, we discussed about the influence towards mode-locked waveform frequency and pulse caused by QD-SOA maximum mode peak gain, active layer loss coefficient, bias current, incident light pulse, fiber nonlinear coefficient. In the meantime, we also take the tunable performance of the laser into consideration. Results showed QD-SOA a better performance than original semiconductor optical amplifier (SOA) in recovery time, line width, and nonlinear coefficients, which makes it possible to output a locked-mode impulse that has a higher impulse power, narrower impulse width as well as the phase is more easily controlled. After a lot of simulations, this laser can realize a 20GHz better locked-mode output pulse after 200 loops, where the power is above 17.5mW, impulse width is less than 2.7ps, moreover, the tunable wavelength range is between 1540nm-1580nm.

Frequency tripling with multimode-lasers

International Nuclear Information System (INIS)

Langer, H.; Roehr, H.; Wrobel, W.G.

1978-10-01

The presence of different modes with random phases in a laser beam leads to fluctuations in nonlinear optical interactions. This paper describes the influence of the linewidth of a dye laser on the generation of intensive Lyman-alpha radiation by frequency tripling. Using this Lyman-alpha source for resonance scattering on strongly doppler-broadened lines in fusion plasmas the detection limit of neutral hydrogen is nearly two orders higher with the multimode than the singlemode dye laser. (orig.) [de

A tuneable, power efficient and narrow single longitudinal mode fibre ring laser using an inline dual-taper fibre Mach–Zehnder filter

International Nuclear Information System (INIS)

Ahmad, H; Dernaika, M; Alimadad, M; Ibrahim, M F; Lim, K S; Harun, S W; Kharraz, O M

2014-01-01

A tuneable single longitudinal mode fibre ring laser with dual-taper fibre filter is proposed and experimentally demonstrated in this paper. The single longitudinal mode operation, and power limitations for a Mach–Zehnder interferometer filter generated from a single mode fibre, are verified for the first time. Incorporating an in-line taper fibre Mach–Zehnder interferometer filter inside the laser ring cavity causes a spatial mode beating interference, resulting in a passive narrow band filter with the ability to generate stable single longitudinal modes. The single longitudinal mode achieves a side mode suppression ratio of more than 60 dB using low pump power. The tuneability of the fibre laser ranges from 1525 to 1562 nm using a passive band pass filter. A study of the stability and limitation of the single longitudinal mode in the Mach–Zehnder tapered fibre is also presented. (paper)

Tunable lasers for waste management photochemistry applications

International Nuclear Information System (INIS)

Finch, F.T.

1978-09-01

A review of lasers with potential photochemical applications in waste management indicates that dye lasers, as a class, can provide tunable laser output through the visible and near-uv regions of the spectrum of most interest to photochemistry. Many variables can affect the performance of a specific dye laser, and the interactions of these variables, at the current state of the art, are complex. The recent literature on dye-laser characteristics has been reviewed and summarized, with emphasis on those parameters that most likely will affect the scaling of dye lasers in photochemical applications. Current costs are reviewed and correlated with output power. A new class of efficient uv lasers that appear to be scalable in both energy output and pulse rate, based on rare-gas halide excimers and similar molecules, is certain to find major applications in photochemistry. Because the most important developments are too recent to be adequately described in the literature or are the likely outcome of current experiments, the basic physics underlying the class of excimer lasers is described. Specific cost data are unavailable, but these new gas lasers should reflect costs similar to those of existing gas lasers, in particular, the pulsed CO 2 lasers. To complete the survey of tunable-laser characteristics, the technical characteristics of the various classes of lasers in the ir are summarized. Important developments in ir laser technology are being accelerated by isotope-separation research, but, initially at least, this portion of the spectrum is least likely to receive emphasis in waste-management-oriented photochemistry

Phenothiazine-Based Dyes in Solar Cell Technology

Directory of Open Access Journals (Sweden)

Andrei Bejan

2017-12-01

Full Text Available Phenothiazine is a fused heterocyclic ring with strong electron-donating character which makes it an important building block for designing organic materials for solar cells applications. The present paper reviews the most recent achievements of phenothiazine-based compounds as dyes in solar cells, with special emphasis on the structure – performance relationship.

Thermally and optically tunable lasing properties from dye-doped holographic polymer dispersed liquid crystal in capillaries

Science.gov (United States)

Chen, Maozhou; Dai, Haitao; Wang, Dongshuo; Yang, Yue; Luo, Dan; Zhang, Xiaodong; Liu, Changlong

2018-03-01

In this paper, we investigated tunable lasing properties from the dye-doped holographic polymer dispersed liquid crystal (HPDLC) gratings in capillaries with thermal and optical manners. The thermally tunable range of the lasing from the dye-doped HPDLC reached 8.60 nm with the temperature ranging from 23 °C to 50 °C. The optically tunable laser emission was achieved by doping azo-dye in HPDLC. The transition of azo-dye from trans- to cis-state could induce the reorientation of LC molecules after UV light irradiation, which resulted in the variation of refractive index contrast of LC-rich/polymer-rich layer in HPDLC. Experimentally, the emission wavelength of lasing showed a blueshift (about 2 nm) coupled with decreasing output intensities. The tunable laser based on HPDLC may enable more applications in laser displays, optical communication, biosensors, etc.

Tunable Fiber Bragg Grating Ring Lasers using Macro Fiber Composite Actuators

Science.gov (United States)

Geddis, Demetris L.; Allison, Sidney G.; Shams, Qamar A.

2006-01-01

The research reported herein includes the fabrication of a tunable optical fiber Bragg grating (FBG) fiber ring laser (FRL)1 from commercially available components as a high-speed alternative tunable laser source for NASA Langley s optical frequency domain reflectometer (OFDR) interrogator, which reads low reflectivity FBG sensors. A Macro-Fiber Composite (MFC) actuator invented at NASA Langley Research Center (LaRC) was selected to tune the laser. MFC actuators use a piezoelectric sheet cut into uniaxially aligned rectangular piezo-fibers surrounded by a polymer matrix and incorporate interdigitated electrodes to deliver electric fields along the length of the piezo-fibers. This configuration enables MFC actuators to produce displacements larger than the original uncut piezoelectric sheet. The FBG filter was sandwiched between two MFC actuators, and when strained, produced approximately 3.62 nm of wavelength shift in the FRL when biasing the MFC actuators from 500 V to 2000 V. This tunability range is comparable to that of other tunable lasers and is adequate for interrogating FBG sensors using OFDR technology. Three different FRL configurations were studied. Configuration A examined the importance of erbium-doped fiber length and output coupling. Configuration B demonstrated the importance of the FBG filter. Configuration C added an output coupler to increase the output power and to isolate the filter. Only configuration C was tuned because it offered the best optical power output of the three configurations. Use of Plastic Optical Fiber (POF) FBG s holds promise for enhanced tunability in future research.

Solid-state polymeric dye lasers

CERN Document Server

Singh, S; Sridhar, G; Muthuswamy, V; Raja, K

2003-01-01

This paper presents a review of the organic solid-state polymer materials, which have become established as a new laser media. The photostability of these materials is discussed. Different types of solid-state lasers built around these materials are also reviewed.

Determination of Metals Present in Textile Dyes Using Laser-Induced Breakdown Spectroscopy and Cross-Validation Using Inductively Coupled Plasma/Atomic Emission Spectroscopy

Directory of Open Access Journals (Sweden)

K. Rehan

2017-01-01

Full Text Available Laser-induced breakdown spectroscopy (LIBS was used for the quantitative analysis of elements present in textile dyes at ambient pressure via the fundamental mode (1064 nm of a Nd:YAG pulsed laser. Three samples were collected for this purpose. Spectra of textile dyes were acquired using an HR spectrometer (LIBS2000+, Ocean Optics, Inc. having an optical resolution of 0.06 nm in the spectral range of 200 to 720 nm. Toxic metals like Cr, Cu, Fe, Ni, and Zn along with other elements like Al, Mg, Ca, and Na were revealed to exist in the samples. The %-age concentrations of the detected elements were measured by means of standard calibration curve method, intensities of every emission from every species, and calibration-free (CF LIBS approach. Only Sample 3 was found to contain heavy metals like Cr, Cu, and Ni above the prescribed limit. The results using LIBS were found to be in good agreement when compared to outcomes of inductively coupled plasma/atomic emission spectroscopy (ICP/AES.

PVA with nopal dye as holographic recording material

Science.gov (United States)

Toxqui-López, S.; Olivares-Pérez, A.; Fuentes-Tapia, I.; Pinto-Iguanero, B.

2011-09-01

Cactus nopal dye is introduced into a polyvinyl alcohol matrix achieving a like brown appearance thick film, such that they can be used as a recording medium. This dye material provides excellent property as photosensitizer, i.e., easy handling, low cost and can be used in real time holographic recording applications. The experimental results show the diffraction efficiencies obtained by recording grating patterns induced by a He-Cd laser (442nm). For the samples, a thick film of polyvinyl alcohol and dye from cactus nopal was deposited by the gravity technique on a glass substrate. This mixture dries to form a photosensitive emulsion.

Long-time dynamics of laser-cooled ions in the TSR storage ring

International Nuclear Information System (INIS)

Mudrich, M.

2000-01-01

This diploma thesis studies experimentally the long-time dynamics of laser-cooled 9 Be + -beams at the TSR under different cooling conditions. The goal is to enlarge the understanding of ultra-cold, non-neutral plasma at high center-of-mass energies. By means of improved measurement capabilities one can now for the first time monitor the entire phase-space over a long time. This makes it possible to quantitatively analyse the possibilities and limitations of laser cooling at a storage ring. Under optimum cooling conditions a regime of high phase-space density is reached, close to the region where influences of Coulomb coupling are expected. Furthermore, a Monte-Carlo model is worked out that qualitatively describes the beam dynamics. The model includes the influence of transverse-longitudinal coupling due to intra beam scattering on the longitudinal phase-space distribution. At high phase-space density a sudden disappearance of intra beam collisions is observed experimentally and possible interpretations are given. (orig.)

5.7  W cw single-frequency laser at 671  nm by single-pass second harmonic generation of a 17.2  W injection-locked 1342  nm Nd : YVO4 ring laser using periodically poled MgO : LiNbO3.

Science.gov (United States)

Koch, Peter; Ruebel, Felix; Bartschke, Juergen; L'huillier, Johannes A

2015-11-20

We demonstrate a continuous wave single-frequency laser at 671.1 nm based on a high-power 888 nm pumped Nd:YVO4 ring laser at 1342.2 nm. Unidirectional operation of the fundamental ring laser is achieved with the injection-locking technique. A Nd:YVO4 microchip laser serves as the injecting seed source, providing a tunable single-frequency power of up to 40 mW. The ring laser emits a single-frequency power of 17.2 W with a Gaussian beam profile and a beam propagation factor of M2beam profile and a beam propagation factor of M2lasers. This work opens possibilities in cold atoms experiments with lithium, allowing the use of larger ensembles in magneto-optical traps or higher diffraction orders in atomic beam interferometers.

Self-injection locking of the DFB laser through an external ring fiber cavity: Application for phase sensitive OTDR acoustic sensor

Directory of Open Access Journals (Sweden)

J.L. Bueno Escobedo

Full Text Available Self-injection locking of DFB laser implemented through the laser coupling with an external fiber optic ring cavity allows its direct employment as an interrogating light source for a phase sensitive OTDR acoustic sensor. Distributed detection and localization of dynamic perturbations of the optical fiber is experimentally demonstrated at the distance of 9270 m. Keywords: Self-injection locking, Optical fiber resonator, φ-OTDR

Rapid fabrication of mesoporous TiO2 thin films by pulsed fibre laser for dye sensitized solar cells

Science.gov (United States)

Hadi, Aseel; Alhabradi, Mansour; Chen, Qian; Liu, Hong; Guo, Wei; Curioni, Michele; Cernik, Robert; Liu, Zhu

2018-01-01

In this paper we demonstrate for the first time that a fibre laser with a wavelength of 1070 nm and a pulse width of milliseconds can be applied to generate mesoporous nanocrystalline (nc) TiO2 thin films on ITO coated glass in ambient atmosphere, by complete vaporisation of organic binder and inter-connection of TiO2 nanoparticles, without thermally damaging the ITO layer and the glass substrate. The fabrication of the mesoporous TiO2 thin films was achieved by stationary laser beam irradiation of 1 min. The dye sensitized solar cell (DSSC) with the laser-sintered TiO2 photoanode reached higher power conversion efficiency (PCE) of 3.20% for the TiO2 film thickness of 6 μm compared with 2.99% for the furnace-sintered. Electrochemical impedance spectroscopy studies revealed that the laser sintering under the optimised condition effectively decreased charge transfer resistance and increased electron lifetime of the TiO2 thin films. The use of the fibre laser with over 40% wall-plug efficiency offers an economically-feasible, industrial viable solution to the major challenge of rapid fabrication of large scale, mass production of mesoporous metal oxide thin film based solar energy systems, potentially for perovskite and monolithic tandem solar cells, in the future.

Reconfiguration of the multiwavelength operation of optical fiber ring lasers by the modifiable intra-cavity induced losses of an in-fiber tip probe modal Michelson interferometer

Science.gov (United States)

Salceda-Delgado, G.; Martinez-Rios, A.; Sierra-Hernandez, J. M.; Rodríguez-Carreón, V. C.; Toral-Acosta, D.; Selvas-Aguilar, R.; Álvarez-Tamayo, R. I.; Castillo-Guzman, A. A.; Rojas-Laguna, R.

2018-03-01

A straightforward and versatile method for switching from single to different multiwavelength laser emission in ring cavity fiber lasers is proposed and demonstrated experimentally. The method is based on using the changeable interference pattern from an optical fiber modal Michelson interferometer as a wavelength selective filter into the ring cavity laser. The interferometer is constructed using a bi-conical tapered fiber and a single-mode fiber segment, with these being spliced together to form an optical fiber tip probe. When the length of the single-mode fiber piece is modified, the phase difference between the interfering modes of the interferometer causes a change in the interferometer free spectral range. As a consequence, the laser intra-cavity losses lead to gain competition, which allows us to adjust the number of simultaneously generated laser lines. A multiwavelength reconfiguration of the laser from one up to a maximum of eight emission lines was obtained, with a maximum SNR of around 47 dBm.

Variable area manifolds for ring mirror heat exchangers

Science.gov (United States)

Eng, Albert; Senterfitt, Donald R.

1988-05-01

A laser ring mirror assembly is disclosed which supports and cools an annular ring mirror of a high powered laser with a cooling manifold which has a coolant flow design which is intended to reduce thermal distortions of the ring mirror by minimizing azimuthal variations in temperature around its circumference. The cooling manifold has complementary pairs of cooling passages each of which conduct coolant in opposite flow directions. The manifold also houses adjusters which vary the depth between the annular ring mirror and each cooling, and which vary the flow area of the cooling passage to produce a control over the cooling characteristics of the cooling manifold.

Bonding of human meniscal and articular cartilage with photoactive 1,8-naphthalimide dyes

Science.gov (United States)

Judy, Millard M.; Nosir, Hany R.; Jackson, Robert W.; Matthews, James Lester; Lewis, David E.; Utecht, Ronald E.; Yuan, Dongwu

1996-05-01

This study focused on meniscal cartilage repair by using the laser-activated photoactive 1,8- naphthalimide dye N,N'-bis-{6-[2-(2-(2- aminoethoxy)ethoxy)ethoxyethyl]amino-1H-benz (de)isoquinolin-1,3(2H)-dion-2- yl}-1,11-diamino-3,6,9-trioxaundecane. Harvested cadaveric human menisci were debrided and carved into strips 1 mm thick, 10 mm long, and 3 mm wide. Each strip was divided into two flaps, the surface painted with photoactive dye, the painted surfaces overlapped, the sample wrapped in Saran film, and the composite sandwiched between two glass slides at a pressure of approximately 3 kg/cm2. The sample then was transilluminated by argon ion laser light of 457.9-nm wavelength at a power density of 200 mW/cm2 with exposure times up to 5 h (3902 J/cm2 energy density). Essentially, the same procedures were performed for human femoral articular cartilage samples. Control experiments were conducted with laser irradiation alone and with dye alone. All the specimens were stored in isotonic saline solution for 2 h after irradiation to ensure hydration. The bond shear-strength was then tested and samples prepared for optical and electron transmission microscopy. Shear strength values of up to 1.8 kg/cm2 for meniscal tissues and 1.2 kg/cm2 for articular cartilaginous tissues were obtained for exposures of 3902 J/cm2. Shear strength values of approximately 0.9 kg/cm2 and 0.4 kg/cm2, respectively, for meniscus and cartilage were obtained with 459 J/cm2 exposure. Dye- and light-only controls exhibited 0 kg/cm2 shear strength values. Microscopy revealed close contact at the bonded surface in the laser-activated, dye-treated-specimens. This study shows that the laser-activated photoactive dyes have the capability of athermally bonding the meniscal and articular cartilage surfaces.

Short-wavelength multiline erbium-doped fiber ring laser by a broadband long-period fiber grating inscribed in a taper transition

International Nuclear Information System (INIS)

Anzueto-Sánchez, G; Martínez-Rios, A

2014-01-01

A stable multiwavelength all-fiber erbium-doped fiber ring laser (EDFRL) based on a broadband long-period fiber grating (LPFG) inscribed in a fiber taper transition is presented. The LPFG’s characteristics were engineered to provide a higher loss at the natural lasing wavelength of the laser cavity. The LPFG inscribed on a taper transition provided a depth greater than 25 dB, and posterior chemical etching provided a broad notch band to inhibit laser generation on the long-wavelength side of the EDF gain. Up to four simultaneous laser wavelengths are generated in the range of 1530–1535 nm. (paper)

Z-scan and optical limiting properties of Hibiscus Sabdariffa dye

Science.gov (United States)

Diallo, A.; Zongo, S.; Mthunzi, P.; Rehman, S.; Alqaradawi, S. Y.; Soboyejo, W.; Maaza, M.

2014-12-01

The intensity-dependent refractive index n 2 and the nonlinear susceptibility χ (3) of Hibiscus Sabdariffa dye solutions in the nanosecond regime at 532 nm are reported. More presicely, the variation of n 2, β, and real and imaginary parts of χ (3) versus the natural dye extract concentration has been carried out by z-scan and optical limiting techniques. The third-order nonlinearity of the Hibiscus Sabdariffa dye solutions was found to be dominated by nonlinear refraction, which leads to strong optical limiting of laser.

Ring-like spatial distribution of laser accelerated protons in the ultra-high-contrast TNSA-regime

Science.gov (United States)

Becker, G. A.; Tietze, S.; Keppler, S.; Reislöhner, J.; Bin, J. H.; Bock, L.; Brack, F.-E.; Hein, J.; Hellwing, M.; Hilz, P.; Hornung, M.; Kessler, A.; Kraft, S. D.; Kuschel, S.; Liebetrau, H.; Ma, W.; Polz, J.; Schlenvoigt, H.-P.; Schorcht, F.; Schwab, M. B.; Seidel, A.; Zeil, K.; Schramm, U.; Zepf, M.; Schreiber, J.; Rykovanov, S.; Kaluza, M. C.

2018-05-01

The spatial distribution of protons accelerated from submicron-thick plastic foil targets using multi-terawatt, frequency-doubled laser pulses with ultra-high temporal contrast has been investigated experimentally. A very stable, ring-like beam profile of the accelerated protons, oriented around the target’s normal direction has been observed. The ring’s opening angle has been found to decrease with increasing foil thicknesses. Two-dimensional particle-in-cell simulations reproduce our results indicating that the ring is formed during the expansion of the proton density distribution into the vacuum as described by the mechanism of target-normal sheath acceleration. Here—in addition to the longitudinal electric fields responsible for the forward acceleration of the protons—a lateral charge separation leads to transverse field components accelerating the protons in the lateral direction.

History and principle of lasers

International Nuclear Information System (INIS)

Townes, Ch.H.; Schwob, C.; Julien, J.; Forget, S.; Robert-Philip, I.; Balcou, Ph.

2010-01-01

In the first article C.H. Townes, the inventor of the maser, describes the work and ideas that led to the invention of the laser. The second article explains how a laser operate and the third article reviews the main different types of laser: solid lasers, gas lasers, diode lasers and dye lasers

Resonance Raman and UV-visible spectroscopy of black dyes on textiles.

Science.gov (United States)

Abbott, Laurence C; Batchelor, Stephen N; Smith, John R Lindsay; Moore, John N

2010-10-10

Resonance Raman and UV-visible diffuse reflectance spectra were recorded from samples of cotton, viscose, polyester, nylon, and acrylic textile swatches dyed black with one of seven single dyes, a mixture of two dyes, or one of seven mixtures of three dyes. The samples generally gave characteristic Raman spectra of the dyes, demonstrating that the technique is applicable for the forensic analysis of dyed black textiles. Survey studies of the widely used dye Reactive Black 5 show that essentially the same Raman spectrum is obtained on bulk sampling from the dye in solution, on viscose, on cotton at different uptakes, and on microscope sampling from the dye in cotton threads and single fibres. The effects of laser irradiation on the Raman bands and emission backgrounds from textile samples with and without dye are also reported. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Combination of 595-nm pulsed dye laser, long-pulsed 755-nm alexandrite laser, and microdermabrasion treatment for keratosis pilaris: retrospective analysis of 26 Korean patients.

Science.gov (United States)

Lee, Sang Ju; Choi, Min Ju; Zheng, Zhenlong; Chung, Won Soon; Kim, Young Koo; Cho, Sung Bin

2013-06-01

Keratosis pilaris (KP) has beenpresented as small keratotic follicular papules with or without surrounding erythema. Various treatments with laser or light therapy have been used for the management of KP with various clinical outcomes. In the present study, we investigated the efficacy and safety of a combination therapy for KP. A total of 29 anatomical sites with KP in 26 patients were treated using a 595-nm pulsed dye laser (PDL) with nonpurpuragenic fluences, a long-pulsed 755-nm alexandrite laser, and microdermabrasion. Clinical improvement was assessed by comparing preand posttreatment clinical photographs and patient satisfaction rates. Evaluation of the clinical results three months after the treatments showed that 12 of the 29 anatomical sites (41.4%) demonstrated Grade 3 clinical improvement, ten (34.5%) had Grade 2 clinical improvement, four (13.8%) showed Grade 1 improvement, and three (10.3%) showed Grade 4 improvement. We observed that KP lesions improved not only in erythema and skin texture, but also in brownish dyschromias. Potential adverse events were not observed, except prolonged posttherapy scaling. Our observations demonstrate that combination therapy using a 595-nm PDL, a long-pulsed 755-nm alexandrite laser, and microdermabrasion can have a positive therapeutic effect on KP.

Amplitude characteristics of a solid-state ring laser with active mode locking

Energy Technology Data Exchange (ETDEWEB)

Belkina, E.M.; Klochan, E.L.; Lariontsev, E.G.

1986-09-01

A system of equations is obtained for the parameters of ultrashort light pulses (USLP) in a solid-state ring laser (SSRL) with periodic loss modulation. Allowance is made for the coupling between counterpropagating USLP due to backscattering in the modulator. The regime of counter-propagating wave frequency capture (CPWFC) is studied. It is shown that the coupling of counterpropagating waves due to backscattering at the modulator ends leads to the suppression of one of the counterpropagating waves during an increase in the detuning of the modulation frequency relative to its optimal value. The influence of rotation on the amplitude characteristics of an SSRL in the CPWFC regime is studied. 9 references.

Toward real-time measurement of atmospheric mercury concentrations using cavity ring-down spectroscopy

Directory of Open Access Journals (Sweden)

X. Faïn

2010-03-01

Full Text Available Cavity ring-down spectroscopy (CRDS is a direct absorption technique that utilizes path lengths up to multiple kilometers in a compact absorption cell and has a significantly higher sensitivity than conventional absorption spectroscopy. This tool opens new prospects for study of gaseous elemental mercury (Hg⁰ because of its high temporal resolution and reduced sample volume requirements (<0.5 l of sample air. We developed a new sensor based on CRDS for measurement of (Hg⁰ mass concentration. Sensor characteristics include sub-ng m⁻³ detection limit and high temporal resolution using a frequency-doubled, tuneable dye laser emitting pulses at ~253.65 nm with a pulse repetition frequency of 50 Hz. The dye laser incorporates a unique piezo element attached to its tuning grating allowing it to tune the laser on and off the Hg⁰ absorption line on a pulse-to-pulse basis to facilitate differential absorption measurements. Hg⁰ absorption measurements with this CRDS laboratory prototype are highly linearly related to Hg⁰ concentrations determined by a Tekran 2537B analyzer over an Hg⁰ concentration range from 0.2 ng m⁻³ to 573 ng m⁻³, implying excellent linearity of both instruments. The current CRDS instrument has a sensitivity of 0.10 ng Hg⁰ m⁻³ at 10-s time resolution. Ambient-air tests showed that background Hg⁰ levels can be detected at low temporal resolution (i.e., 1 s, but also highlight a need for high-frequency (i.e., pulse-to-pulse differential on/off-line tuning of the laser wavelength to account for instabilities of the CRDS system and variable background absorption interferences. Future applications may include ambient Hg⁰ flux measurements with eddy covariance techniques, which require measurements of Hg⁰ concentrations with sub-ng m⁻³ sensitivity and sub-second time

Inter-dependence of the electron beam excitations with the free electron laser stability on the super-ACO storage ring

CERN Document Server

Couprie, Marie Emmanuelle; Nutarelli, D; Renault, E; Billardon, M

1999-01-01

Storage ring free electron lasers have a complex dynamics as compared to the LINAC driven FEL sources since both the laser and the recirculating electron beam behaviours are involved. Electron beam perturbations can strongly affect the FEL operation (start-up, stability) whereas the FEL can stabilize beam instabilities. Experimental analysis together with simulations are reported here. Improvements of the Super-ACO FEL for users is discussed, and consequences are given in terms of electron beam tolerances for a source development for users.

Robust gap repair in the contractile ring ensures timely completion of cytokinesis.

OpenAIRE

Silva, AM; Osório, DS; Pereira, AJ; Maiato, H; Pinto, IM; Rubinstein, B; Gassmann, R; Telley, IA; Carvalho, AX

2016-01-01

Cytokinesis in animal cells requires the constriction of an actomyosin contractile ring, whose architecture and mechanism remain poorly understood. We use laser microsurgery to explore the biophysical properties of constricting rings in Caenorhabditis elegans embryos. Laser cutting causes rings to snap open. However, instead of disintegrating, ring topology recovers and constriction proceeds. In response to severing, a finite gap forms and is repaired by recruitment of new material in an acti...

Photodetection of early cancer by laser-induced fluorescence of a tumor-selective dye: apparatus design and realization

Science.gov (United States)

Wagnieres, Georges A.; Depeursinge, Christian D.; Monnier, Philippe; Savary, Jean-Francois; Cornaz, Piet F.; Chatelain, Andre; van den Bergh, Hubert

1990-07-01

An apparatus is designed and realized to detect "early" cancer at the surface of the hollow organs in the human body by endoscopic means. The tumor is localized by the laser induced fluorescence of a dye (HPD) which concentrates selectively in the neoplastic tissue after intravenous injection. Fluorescence contrast between the tumor and its normal surroundings is enhanced by subtracting the background autofluorescence which occurs in both types of tissue. This is done by means of 2-color digital images manipulation in real-time. Preliminary clinical tests of the apparatus demonstrated the detection of carcinoma in situ in the esophagus.

Preparation and flow cytometry of uniform silica-fluorescent dye microspheres.

Science.gov (United States)

Bele, Marjan; Siiman, Olavi; Matijević, Egon

2002-10-15

Uniform fluorescent silica-dye microspheres have been prepared by coating preformed monodispersed silica particles with silica layers containing rhodamine 6G or acridine orange. The resulting dispersions exhibit intense fluorescent emission between 500 and 600 nm, over a broad excitation wavelength range of 460 to 550 nm, even with exceedingly small amounts of dyes incorporated into the silica particles (10-30 ppm, expressed as weight of dye relative to weight of dry particles). The fluorescent particles can be prepared in micrometer diameters suitable for analyses using flow cytometry with 488-nm laser excitation.

Heavy ion storage rings

International Nuclear Information System (INIS)

Schuch, R.

1987-01-01

A brief overview of synchrotron storage rings for heavy ions, which are presently under construction in different accelerator laboratories is given. Ions ranging from protons up to uranium ions at MeV/nucleon energies will be injected into these rings using multiturn injection from the accelerators available or being built in these laboratories. After injection, it is planned to cool the phase space distribution of the ions by merging them with cold electron beams or laser beams, or by using stochastic cooling. Some atomic physics experiments planned for these rings are presented. 35 refs

DFT Study of the Structure, Reactivity, Natural Bond Orbital and Hyperpolarizability of Thiazole Azo Dyes

Directory of Open Access Journals (Sweden)

Osman I. Osman

2017-02-01

Full Text Available The structure, reactivity, natural bond orbital (NBO, linear and nonlinear optical (NLO properties of three thiazole azo dyes (A, B and C were monitored by applying B3LYP, CAM-B3LYP and ωB97XD functionals with 6-311++G** and aug-cc-pvdz basis sets. The geometrical parameters,dipolemoments,HOMO-LUMO(highest occupied molecular orbital,lowest unoccupied molecular orbital energy gaps, absorption wavelengths and total hyperpolarizabilities were investigated in carbon tetrachloride (CCl4 chloroform (CHCl3, dichloromethane (CH2Cl2 and dimethlysulphoxide (DMSO. The donor methoxyphenyl group deviates from planarity with the thiazole azo moiety by ca. 38◦; while the acceptor dicyanovinyl, indandione and dicyanovinylindanone groups diverge by ca. 6◦. The HOMOs for the three dyes are identical. They spread over the methoxyphenyl donor moiety, the thiazole and benzene rings as π-bonding orbitals. The LUMOs are shaped up by the nature of the acceptor moieties. The LUMOs of the A, B and C dyes extend over the indandione, malononitrile and dicyanovinylindanone acceptor moieties, respectively, as π-antibonding orbitals. The HOMO-LUMO splittings showed that Dye C is much more reactive than dyes A and B. Compared to dyes A and B, Dye C yielded a longer maximum absorption wavelength because of the stabilization of its LUMOs relative to those of the other two. The three dyes show solvatochromism accompanied by significant increases in hyperpolarizability. The enhancement of the total hyperpolarizability of C compared to those of A and B is due to the cumulative action of the long π-conjugation of the indanone ring and the stronger electron-withdrawing ability of the dicyanovinyl moiety that form the dicyanovinylindanone acceptor group. These findings are facilitated by a natural bond orbital (NBO technique. The very high total hyperpolarizabilities of the three dyes define their potent nonlinear optical (NLO behaviour.

Dermatological laser treatment

International Nuclear Information System (INIS)

Moerk, N.J.; Austad, J.; Helland, S.; Thune, P.; Volden, G.; Falk, E.

1991-01-01

The article reviews the different lasers used in dermatology. Special emphasis is placed on the treatment of naevus flammeus (''portwine stain'') where lasers are the treatment of choice. Argon laser and pulsed dye laser are the main lasers used in vascular skin diseases, and the article focuses on these two types. Copper-vapour laser, neodymium-YAG laser and CO 2 laser are also presented. Information is provided about the availability of laser technology in the different health regions in Norway. 5 refs., 2 figs

Synthesis and analysis of nickel dithiolene dyes in a nematic liquid crystal host. 1998 summer research program for high school juniors at the University of Rochester's Laboratory for Laser Energetics. Student research reports

International Nuclear Information System (INIS)

Lippa, I.

1999-03-01

The Liquid Crystal Point Diffraction Interferometer (LCPDI) can be employed to evaluate the Omega Laser system for optimum firing capabilities. This device utilizes a nickel dithiolene infrared absorbing liquid crystal dye dissolved in a liquid crystal host medium (Merck E7). Three nickel dithiolene dyes were characterized for both their solubility in the E7 host and their infrared spectral absorption

Ablation of intervertebral discs in dogs using a MicroJet-assisted dye-enhanced injection device coupled with the diode laser

Science.gov (United States)

Bartels, Kenneth E.; Henry, George A.; Dickey, D. Thomas; Stair, Ernest L.; Powell, Ronald; Schafer, Steven A.; Nordquist, Robert E.; Frederickson, Christopher J.; Hayes, Donald J.; Wallace, David B.

1998-07-01

Use of holmium laser energy for vaporization/coagulation of the nucleus pulposus in canine intervertebral discs has been previously reported and is currently being applied clinically in veterinary medicine. The procedure was originally developed in the canine model and intended for potential human use. Since the pulsed (15 Hz) holmium laser energy exerts photomechanical and photothermal effects, the potential for extrusion of additional disc material to the detriment of the patient is possible using the procedure developed for the dog. To reduce this potential complication, use of diode laser (805 nm - CW mode) energy, coupled with indocyanine green (ICG) as a selective laser energy absorber, was formulated as a possible alternative. Delivery of the ICG and diode laser energy was through a MicroJet device that could dispense dye interactively between individual laser 'shots.' Results have shown that it is possible to selectively ablate nucleus pulposus in the canine model using the device described. Acute observations (gross and histopathologic) illustrate that accurate placement of the spinal needle before introduction of the MicroJet device is critically dependent on the expertise of the interventional radiologist. In addition, the success of the overall technique depends on consistent delivery of both ICG and diode laser energy. Minimizing tissue carbonization on the tip of the MicroJet device is also of crucial importance for effective application of the technique in clinical veterinary medicine.

Lasers: principles, applications and energetic measures

International Nuclear Information System (INIS)

Subran, C.; Sagaut, J.; Lapointe, S.

2009-01-01

After having recalled the principles of a laser and the properties of the laser beam, the authors describe the following different types of lasers: solid state lasers, fiber lasers, semiconductor lasers, dye lasers and gas lasers. Then, their applications are given. Very high energy lasers can reproduce the phenomenon of nuclear fusion of hydrogen atoms. (O.M.)

Laser welding and collagen crosslinks

Energy Technology Data Exchange (ETDEWEB)

Reiser, K.M.; Last, J.A. [California Univ., Davis, CA (United States). Dept. of Medicine; Small, W. IV; Maitland, D.J.; Heredia, N.J.; Da Silva, L.B.; Matthews, D.L. [Lawrence Livermore National Lab., CA (United States)

1997-02-20

Strength and stability of laser-welded tissue may be influenced, in part, by effects of laser exposure on collagen crosslinking. We therefore studied effects of diode laser exposure (805 nm, 1-8 watts, 30 seconds) + indocyanine green dye (ICG) on calf tail tendon collagen crosslinks. Effect of ICG dye alone on crosslink content prior to laser exposure was investigated; unexpectedly, we found that ICG-treated tissue had significantly increased DHLNL and OHP, but not HLNL. Laser exposure after ICG application reduced elevated DHLNL and OHP crosslink content down to their native levels. The monohydroxylated crosslink HLNL was inversely correlated with laser output (p<0.01 by linear regression analysis). DHLNL content was highly correlated with content of its maturational product, OHP, suggesting that precursor-product relations are maintained. We conclude that: (1)ICG alone induces DHLNL and OHP crosslink formation; (2)subsequent laser exposure reduces the ICG-induced crosslinks down to native levels; (3)excessive diode laser exposure destroys normally occurring HLNL crosslinks.

Laser-assisted indocyanine green dye angiography accurately predicts the split-thickness graft timing of integra artificial dermis.

Science.gov (United States)

Fourman, Mitchell S; Phillips, Brett T; Fritz, Jason R; Conkling, Nicole; McClain, Steve A; Simon, Marcia; Dagum, Alexander B

2014-08-01

The use of an artificial dermal substitute such as Integra-a bilaminate combination of thin silicone and cross-linked bovine tendon collagen and chondroitin-6-sulfate-has become a popular method to address large surface area wounds or smaller, complex wounds devoid of a vascular bed. The incorporation of Integra depends on a vascular wound bed or periphery and can take 4 weeks or longer to occur. If the Integra has not fully incorporated at the time of placement of the split-thickness graft, complete graft loss may result. The availability of a minimally invasive method to assess the incorporation of Integra would be of great value. Two 5 × 10-cm paraspinal full-thickness wounds were created on 3 female swine. Wounds were randomly assigned full-thickness skin graft or Integra (Plainsboro, NJ) treatment. Both types of grafts were placed after the application of fibrin glue (Tisseel, Deerfield, Ill) to the wound bed. Laser Doppler imaging (LDI) (Moor), indocyanine green dye (ICG) angiography (LifeCell SPY), and clinical scoring were performed weekly for a period of 8 weeks after grafting. At 4 weeks, the silicone layer of the Integra was removed, and a culture of autologous keratinocytes was applied. A 4-mm punch biopsy sample of each graft was taken 1, 2, 4, 6, 7, and 8 weeks postoperatively for histologic analysis. Both ICG angiography and LDI perfusion measurements noted an increase in perfusion at the Integra graft site that peaked 3 weeks after grafting, corresponding with the start of neovascularization and the optimal time for the application of a split-thickness skin graft. indocyanine green dye angiography measurements exhibit greater reproducibility between animals at late time points as compared with LDI. This decrease in LDI precision is directly related to increases in scar tissue thickness of greater than 5 mm as determined via histologic analysis and corresponds with the accepted maximum penetration depth of the LDI laser. Indocyanine green dye

Some characteristics of isotopic separation laser systems

International Nuclear Information System (INIS)

Pochon, E.

1988-01-01

The principle of Laser Isotope Separation (LIS) is simple and based on either selective electronic photoexcitation and photoionization of atomic vapor, or selective vibrational photoexcitation and photodissociation of molecules in the gas phase. These processes, respectively called SILVA (AVLIS) and SILMO (MLIS) in France, both use specific laser systems with wavelengths spanning from infrared to ultraviolet. This article describes briefly some of the characteristics of a SILVA laser system. Following a three-step process, a SILVA laser system is based on dye copper vapor lasers. The pulse dye lasers provide the tunable laser light and are optically pumped by copper vapor laser operating at high repetition rates. In order to meet plant laser system requirements, the main improvements under way relate to copper vapor laser devices the power capability, efficiency, reliability and lifetime of which have to be increased. 1 fig

High-resolution absorption spectrum of the 61S0 → 63P1 transition in mercury with a Cw dye laser

International Nuclear Information System (INIS)

Crane, J.K.; Erbert, G.V.; Mostek, S.D.; Kerlin, R.C.; Paisner, J.A.

1985-01-01

Using a stabilized single-frequency commercial dye laser and an external cavity doubling crystal, we have measured the isotope shifts of mercury for the 6 1 S 0 → 6 3 P 1 transition with an accuracy of 4 MHz. We describe the method for generating single-frequency light at 2537 A and compare the results of our measurements of the isotope shifts with previous work. 7 refs., 5 figs., 1 tab

Sub-wavelength plasmon laser