Energy transfer in solid-state dye lasers based on methyl methacrylate co-doped with sulforhodamine B and crystal violet

Laser action in methyl methacrylate （MMA） co-doped with sulforhodamine B and crystal violet dyes was investi- gated. The dye mixture was incorporated into a solid polymeric matrix and was pumped by a 532-nm Nd：YAG laser. Distributed feedback dye laser （DFDL） action was induced in the dye mixture using a prism arrangement both in the donor and acceptor regions by an energy transfer mechanism. Theoretically, the characteristics of acceptor and donor DFDLs, and the dependence of their pulse widths and output powers on acceptor-donor concentrations and pump power, were studied. Experimentally, the output energy of DFDL was measured at the emission peaks of donor and acceptor dyes for different pump powers and different acceptor-donor concentrations. Tuning of the output wavelength was achieved by varying the period of the gain modulation of the laser medium. The laser wavelength showed continuous tunability from 563 nm to 648 nm.

Medium performance effect on the high output energy from a xenon lamp-pumped pyrromethene-567 solid-state dye laser

In order to obtain a high output energy from a xenon lamp-pumped solid-state dye laser, homogeneities of laser mediums and flatnesses of medium faces with different processing treatments are discussed in the paper. The mediums without aging treatment, which are prepared by using a prepolymer process and have diamond-machined end faces to produce the required optical finish, give a highest laser output of 281.9 mJ with 0.215% slope efficiency at 2.0x 10^-4 mol/L. The best medium lifetime is 21 shots to 50% of original output equating 74.6 k J/liter.

PM567-Doped solid dye lasers based on PMMA

Polymers are a kind of attractive hosts for laser dyes due to their high transparency in both pumping and lasing ranges and superior optical homogeneity. In this paper solid dye samples based on polymethyl methacrylate （PMMA） doped with different concentrations of 1, 3, 5, 7, 8 -pentamethyl-2, 6-diethylpyrromethene-BF2 （PM567） are prepared. The absorption, fluorescence and lasing spectra of the samples are obtained. Wide absorption and fluorescence bands are obtained and a red shift of the maxima of the lasing emission spectra is observed. With the second-harmonic generation of Q-switched Nd：YAC laser （532 nm, -20 ns） pumping the samples longitudinally, the slope efficiencies of the samples are obtained. There is an optimal dye concentration for the highest slope efficiency when the pumping energy is lower than some typical value （-250 mJ）, and the highest slope efficiency 35.6% is obtained in the sample with a dye concentration of 2 × 10^-4 mol/L. Pumping the samples at a rate of 10Hz with a pulse energy as high as 200 mJ （the fluence is 0.2 J/cm^2）, the output energy drops to one-half of its initial value after approximate 15500 pulses and the normalized photostability is 5.17CJ/mol. A kind of solid dye laser which could have some applications is built.

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

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

FLASHLAMP- PUMPED PULSED DYE LASER IN TREATMENT OF PORT- WINE STAINS

To assess the effectiveness of the flashlamp- pumped pulsed dye laser (Photogeneca V, Synosure Corp, Boston, United States) in the treatment of port- wine stains. Methods. One hundred and ninety- four consecutive patients with port- wine stains were treated with a flashlamp- pumped pulsed dye laser in Peking Union Medical College Hospital from January 1998 to August 1999. Results. Of 194 patients who completed treatment, 56.2％ had more than 60％ fading of the lesion and only 6.7％ had less than 20％ fading. An average of 3.6 treatments were needed to achieve more than 60％ fading. The response was better in children than in adults, although the difference was not significant. Pigmentary change (usually transient) occurred in 3.1％ of patients. Conclusions. This study confirms the efficacy of the flashlamp- pumped pulsed dye laser in the treatment of port- wine stains in children and adults.

PULSBD DYE LASER THROMBOLYSIS IN VITRO AND ITS EFFECTS ON VASCULAR FUNCTION AND STRUCTURE IN VIVO

The purpose of the study is to evatuate the feasibility of pulsed dye laser(PDL)throm bolysis In vitro and the effect of PDL on vascular function and structure invivo.In vitro,fifty hum an throm biwere divided into laser treated group(n=35),irritation group(n=11),and controgroup(n=4).In the laser treated group thethrom biwere irradiated by PDL with 300 pulses at 100m J/pulse.No irradiation wasgiven to the throm bi in the irritation group,while the catheter was put to and frointo the throm bi for there times,Neither irradintion nor irritation was given to thethrom bi in the controlgroup.Sixteen healthy dogs were studied in vivo.Under theguidance of the guide-w ire PDL catheter was put into the left coronary arteries(n=16)from which PDL was em itted for 1380±60 pulses at 100m J/pulse,whereasthe rightcoronary srteries(n=16)which did not receieve PDL em ission were servedas irritation group.Then the PDL were irradiated directly to the right coronaryarterial wall in the irritation group without the guidance of the guide-wire.AfterPDL irradiation.the weight of the throm bi was reduced from 1.79±0.23g to0.61±0.12g while in the irritation group theweight of the throm biwas only reducedfrom 1.65±0.19 to 1.42±0.15g.In these two aroups the reduction of throm biweightwere 68%±6% and 15%±7% resoectively(P【0.001).No self-dissolution of thethrom bi occurred in the control group.The finding under the contrast phasem icroscope indicated 91% of the debris size were smaller than the size of redcells.In vivo study,coronary angiography showed that no changes in luminalduam eter of both groups.Nomechanicalor thermal in jury to the coronary arterieswas found excepta light irregularity of the intima.PDL Throm bolysis was effectivein vitro.There was no mechanicaldam age or therm al in jury to the vessels during theprocedure of intracoronary PDL irradiation in vivo.

Huge Recalcitrant Warts Treated with Pulse Dye Laser after Conventional Therapies and Others Destructive Physical Modalities Failed

Cutaneous infections with the human papilloma virus, despite being almost always asymptomatic, can induce slow-growing lesions knowed as warts that can remain subclinical for long periods of time. There are several therapeutical options namely keratolytics, retinoids, imiquimod, cryotherapy, electrosurgery, lasers and classic surgery, but none has antiviral effects. We describe the case of a patient with large warts located on the dorsal surface of the right hand, treated with cryotherapy, CO2 laser and topical imiquimod having either no clinical response or quick relapse. Treatment with PDL was started and after 13 sessions, the patient was without lesions, with a good cosmetic result and so far without relapse. This case report is relevant to us and deserves to be published because of the size of the lesions and the great response to PDL despite all the failures with the other treatments.

CW-Dye Laser Spectrometer for Ultrahigh Resolution Spectroscopy: Design and Performance

This work is devoted to building-up of ultrahigh resolution cw-dye laser spectrometer system. This system used self-frequency-stabilized and temperature-compensated plano-confocal reference cavity. The one-way propagation is achieved using new construction of optical diode. The laser frequency selection and tuning is accomplished using Mach-Zehnder interferometer of free spectral range 42.5 GHz. In combination with computerized tunable radio frequency technique, this system is capable of a resolution of about ±1 KHz. Applications for measuring high lying, weakly occupied metastable states of free atoms (line 548.792 nm of V-51) are investigated to a high degree of accuracy. The results of the constants A and B of the hfs as measured by fluorescence spectroscopy show that A = 160.762 and B = -17.918, while the obtained results for the hfs constants A and B as measured by laser-RF double resonance technique give A = 160.9950 and B = -17.3358.

Early Pulsed Dye Laser Treatment for Infantile Hemangiomas: An Open Study for 50 Japanese Infancies

Infantile hemangiomas, occurring at birth or during the first weeks of life, are benign vascular tumors with an initial proliferative phase and a later involutional phase. The massive proliferation on the key regions and unpredicted regression may threaten?life. Thus, early management of infantile hemangiomas is necessary for affected infancies. Recent studies showed that propranolol for infantile hemangiomas had high efficacy for disappearance or reduction of infantile hemangiomas. However, a most recent study demonstrated existence of propranolol-resistant infantile hemangiomas. Therefore, we retrospectively evaluated efficacy of established early pulsed dye laser treatment for infantile hemangiomas in the 50 Japanese infancies which were applied in the period from 2000 to 2005, because our series included from the plaque subtype to the more proliferative tumor subtype. High efficacy in both subtypes suggests that early pulsed dye laser treatment can still be included as the first option for the mixed type of infantile hemangiomas and that pulsed dye laser treatment may be useful as the second line for the propranolol-resistant mixed type of infantile hemangiomas.

Effects of lower fluence pulsed dye laser irradiation on production of collagen and the mRNA expression of collagen relative gene in cultured fibroblasts in vitro

Background Lower fluence of 585-nm flashlamp-pumped pulsed dye laser has been successfully used as a nonablative technique in the treatment of wrinkles. The objective of this study was to evaluate the effect of the pulsed dye laser （585 nm） on the production of collagen and the mRNA expression of collagen related gene in fibroblasts in vitro. Methods Cultured fibroblasts were treated with a 585-nm flashlamp-pumped pulsed dye laser （ fluence 3 J/cm^2, 4 J/cm^2, spot size 7 mm, pulse duration 450 12s）. The production of collagen and the mRNA expression of transforming growth factor （TGF）-β1, SMAD2, SMAD3, SMAD4, SMAD7 and type Ⅰ procollagen α1, α2 in fibroblasts were investigated by colorimetry or real time polymerase chain reaction. Results The production of collagen was significantly up-regulated after treatment with a 585-nm flashlamp-pumped pulsed dye laser with a fluence of 3 J/cm^2 （P 〈0.001）. The mRNA expression of TGF- β1, SMAD2, SMAD3, SMAD4, SMAD7 and procollagen I was significantly up-regulated after treatment with a 585-nm flashlamp-pumped pulsed dye laser with a fluence of 3 J/cm^2 （P 〈0.001）. No significant difference of mRNA expression of SMAD2, SMAD3, SMAD4, SMAD7 and type Ⅰ procollagen was found between controls and fibroblasts treated with pulsed dye laser with a fluence of 4 J/cm^2 （P 〉0.05）. Conclusions Lower fluence （3 J/cm^2） pulsed dye laser increased the collagen production in fibroblasts by up-regulating TGF-β1, SMAD2, SMAD3, SMAD4, SMAD7 and type Ⅰ procollagen mRNA expression. These may be the reason it can be effectively used in the treatment of wrinkles.

A New Organic Up-conversion Laser Dye HEASPS

A new organic dye, trans-4-[p-(N-hydroxyethyl-N-ethylamino)styryl]-N-methyl- pyridinium p-toluene sulfonate (HEASPS) has been synthesized and its structure has been determined. Pumped with a 1064 nm, 50 ps laser pulses, 0.05 mol/L HEASPS/DMF solution showed the two-photon pumped (TPP) output/input efficiency of 9.1% which is higher than that of known TPP laser dyes trans-4-[p-(N-hydroxyethyl-N-methylamino) styryl]-N-methylpyridinium iodide (ASPI) and trans-4-[p-(N-hydroxyethyl-N-methylamino) styryl]-N-methylpyridinium p-toluene sulfonate (HMASPS) at the same experimental conditions.

Optofluidic microring dye laser embedded in polydimenthylsiloxane with reduced threshold

We demonstrate an integrated optofluidic microring dye laser with a relatively low threshold on a polydimenthylsiloxane(PDMS) chip.The chip was fabricated through conventional soft lithography.It consists of a liquid waveguide with microring structure providing the feedback.A reduced threshold is realized due to the unique design of the bus waveguide across the center of the microring structure,which results in a great reduction in the cavity losses.Laser dye rhodamine 6G(R6G) dissolved in benzyl alcohol was injected into the microfluidic channel as the gain medium.When the dye laser was pumped with a pulsed laser at 532 nm,the dye laser oscillation was achieved with a threshold of only 4?5 μJ mm-2.The convenience in fabrication and operation makes the optofluidic microring dye laser a promising underlying photonic component in the integrated optofluidic systems.

Photo-Physical Properties of Stilbine-3 (STB-3) Laser Dyes Embedded in Sol-Gel Glasses

Solid-state tunable dye laser materials developed by incorporation of stable laser dye molecules into solid host matrices like polymers, organically modified silicates (ORMOSILS) and porous sol-gel glasses. These materials have technical advantages such as compactness, better manageability and suitability for field measurement. The recent research work with highly porous sol-gel glasses having good transparency in UV-Near UV region used as solid host for solid-state dye laser materials has attracted a great deal of attention because of its high potential utility than polymers. Two different procedure’s are used for incorpoerating the Stilbine-3 (STB-3) laser dyes into porous sol-gel matrices such as dope or dip methods. In dope method dye is mixed at the sol state and drying is carried out afterward;while in dip method matrix is first prepared and the matrix is dipped in desired dye solution. After preparation of these dye embedded sol-gel glasses we studied their spectroscopic properties of using absorption and fluorescence spectroscopy. Along with spectroscopy properties, the studies for longevity or the shelf life and lasing action of these materials were carried out. Laser dye STB-3 incorporated in sol-gel glass samples shows the same result as in methanolic solution.

Synthesis and Characterization of a New Organic Up-conversion Laser Dye HMASPS

A new organic dye, trans-4-[4'-(N-hydroxyethyl-N-methylamino)styryl]-N-methylpyridinium p-toluene sulfonate (HMASPS) has been synthesized and its structure has been determined. Pumped with a 1064 nm, 50 ps laser pulses, 0.05 mol/L HMASPS/DMF solution showed the two-photon pumped (TPP) output/input efficiency of 8.4% which is higher than that of trans-4-[p-(N-hydroxyethyl-N-methylamino) styryl]-N-methylpyridinium iodide (ASPI)(1) at the same pump level.

18 fs Pulses-New Advance of CPM Dye Laser

Since the 1980s, colliding pulse mode-locked (CPM) ring dye laser has been themajor system to generate femtosecond light pulses owing to its reliability, stability andavailability in materials and equipment though Ti-sapphire laser has now demonstratedthe potential to produce short pulses. It has been reported that as short as 27

Excited State Interaction of Laser Dyes and Silver Nanoparticles in Different Media

Quenching the fluorescence of the dyes 3-(4’-dimethylaminophenyl)-1-(1H-pyrrol-2-yl)prop-2-en-1-one (DMAPrP), 3- (4’-dimethylaminophenyl)-1-(2-furanyl)prop-2-en-1-one (DMAFP) and 3-(4’-dimethylaminophenyl)-1-(2-thienyl)prop- 2-en-1-one (DMATP) has been investigated in the presence of silver cation and silver nanoparticles in different media. The results of the quenching experiments were analyzed using Stern-Volmer equation. Quenching the fluorescence of the dyes decreased with increasing medium viscosity. The Stern-Volmer constant (KSV) values in the absence and presence of ethylene glycol show that the quenching efficiencies decrease as the medium viscosity increases indicating that the quenching process is a diffusion-controlled process, and this is consistent with a dynamic-type quenching.

Comparative Study of Coumarin-120 (C-120) and Stilbine-3 (STB-3) Laser Dyes Doped in Sol-Gel Glasses

In 1967 the first work in solid state dye laser was performed by doping rhodamine dyes in Polymethylmethacrylate (PMMA) materials. Since then some materials like various types of polymers, co-polymers, poly composite glasses have been used as host matrices for doping different laser dyes. Polymers suffer from limited mechanical and thermal stability. Hence glasses can be the alternative hosts. However, because of high processing temperature leading to permanent destruction of dye molecules, the conventional glass preparation technique is not suitable for the introduction of organic laser dyes. This difficulty can be overcome by introducing the laser dye molecules in sol-gel glass which is prepared at low temperature. Recent work with sol-gel glasses shows that these glasses may prove to be better materials compared to polymeric materials because glasses being hard, best optically transparency in Near UV-UV and Visible region and show better photostability. In this research work we reported, comparative study of the photophysical properties of Coumarin-120 (C-120) belonging to 7-aminocoumarin family having two hydrogen atoms attached to the N atom at the 7-position, with Stilbene-3 (STB-3) in three types of HCl catalyzed SiO2 sol-gel matrices prepared by Method I, Method II and Method III respectively.

两种激光治疗儿童中心点突起型蜘蛛痣的临床研究

目的:探研2种激光方法在儿童中心点突起型蜘蛛痣治疗中的疗效、不良反应及并发症。方法:选取2020年10月至2022年10月期间由河北省儿童医院整形外科门诊确诊的中心点突起型蜘蛛痣患儿60例为研究对象,采用数字表法随机分组,分为595nm脉冲染料激光组,超脉冲CO_(2)点阵激光组,每组30例。对患儿的治疗次数、治疗效果、不良反应以及并发症情况进行评估。结果:经过随访得知,595nm组较CO_(2)组治疗次数多,差异有统计学意义(P<0.05);两组一次治疗后治愈率分别为80%、95%,差异有统计学意义(P<0.05);两组经多次治疗后治愈率差异无统计学意义(P>0.05);595nm组较CO_(2)组不良反应大,差异有统计学意义(P<0.05);随访12周,并发症差异无统计学意义(P>0.05)。结论:595nm脉冲染料激光及超脉冲CO_(2)点阵激光在儿童中心点突起型蜘蛛痣的治疗中均效果显著,各有优缺点,可根据病灶特点及患儿要求选择适当的治疗方法。