Red Diode Laser Research Articles

Lasing Action in Dual-Doped Organic Microcavity with Cascade Energy Transfer

In this paper, we studied lasing action in dual-doped organic microcavity with cascade Forster energy transfer between polymer and two fluorescent dyes in surface emitting microcavities, which formed by sandwiching a poly(N-vinylcarzole) (PVK) film doped with 8-trishydroxyquinoline (Alq3) and 4-(dicyanomethylene)-2-tert-butyl-6 (1, 1, 7, 7-tet ramethyljulolidyl-9-enyl)-4H–pyran (DCJTB) between a distributed Bragg reflector (DBR) and a silver film mirror. The sample was optically pumped by a frequency-tripled Nd:YAG laser delivering 5.55ns pulses at 355nm with a 10Hz repetition rate. By optimizing the concentrations of Alq3 and DCJTB in PVK, a low lasing threshold of about 9.5µJ per pulse attributed to efficient cascade Forster energy transfer form PVK and Alq3 to DCJTB was obtained. The full width at half maximum (FWHM) of the emission was about 2nm with the peak wavelength at 628nm. Our results demonstrate that the PVK:Alq3:DCJTB could be a promising candidate as gain medium for red organic diode lasers.

Selective laser vaporization of polypropylene mesh used in treatment of female stress urinary incontinence and pelvic organ prolapse: Preliminary studies using a red diode laser

The most common mesh-related complication experienced by patients undergoing transvaginal polypropylene synthetic slings for stress urinary incontinence (SUI) and transvaginal pelvic organ prolapse (POP) repair with mesh is vaginal mesh erosion. More than half of the patients who experience erosion from synthetic mesh require surgical excision which is technically challenging and risks damage to healthy adjacent tissue. This study explores selective laser vaporization of polypropylene suture/mesh materials commonly used in SUI and POP. A compact, 7 Watt, 647-nm, red diode laser was operated with a radiant exposure of 81 J/cm(2) , pulse duration of 100 milliseconds, and 1.0-mm-diameter laser spot. The 647-nm wavelength was selected because its absorption by water, hemoglobin, and other tissue chromophores is low, while polypropylene absorption is high. Laser vaporization of ∼200-µm-diameter polypropylene suture/mesh strands, in contact with fresh urinary tissue samples was performed, ex vivo. Temperature mapping of suture/mesh samples with a thermal camera was also conducted. Selective vaporization of polypropylene suture and mesh using a single laser pulse was achieved with peak temperatures of 180 and 232°C, respectively, while direct laser irradiation of tissue alone resulted in only a 1°C temperature increase. Selective laser vaporization of polypropylene suture/mesh materials is feasible without significant thermal elevation in the adjacent tissue. This technique may be useful for treatment of eroded mesh after SUI or POP procedures that require surgical revision.

Laser therapy applications for osteoarthritis and chronic joint pain – A randomized placebo-controlled clinical trial

AbstractA randomized placebo-controlled clinical trial to evaluate an adjunctive treatment modality for pain associated with knee disorders was conducted utilizing a therapeutic laser system (low energy, non-surgical).The therapeutic laser system utilized a dual wavelength, multiple diode laser cluster probe with five super-pulsed 905 nm near-infrared (NIR) laser diodes, each emitting at 40 mW average power and four continuous wave 660 nm visible (VIS) red laser diodes, each emitting at 25 mW. It was used as an adjunctive modality providing 12 treatments, three times a week to a homogeneous patient population (n=126), in combination with standardized chiropractic techniques, to evaluate effectiveness on subjects presenting with osteoarthritis and knee pain. The primary endpoint was measured by the visual analog scale (VAS) to assess pain levels on a scale of 0–10. The success criteria for an individual patient in this study were identified as an improvement of 30% or more in the VAS from baseline to 12th treatment and/or an improvement of 20% or more in the VAS from baseline to 30-day follow-up evaluation.The data obtained in the study demonstrated that the present therapeutic laser system provided significant pain relief and osteoarthritic improvements in all primary evaluation criteria, with a statistical and clinical significance of

S053032 吸光度法による軸対称乱流噴流中での二成分瞬時濃度測定

Turbulent diffusion phenomena are of practical importance with many engineering and environmental field (e.g., in the reactor design and the prediction of pollutant diffusion). In order to clarify turbulent diffusion field experimentally, it is useful to measure instantaneous concentrations of multiple species simultaneously in a turbulent flow. In the present study, measurement system for concentrations of two species using absorption method has been developed, and instantaneous concentrations of two species in a turbulent jet were measured. Two laser diodes (LDs) with different wavelength are used as light sources; red LD (635 nm) and green LD (532 nm). It is confirmed that the instantaneous concentrations of two species in a turbulent jet can be measured by the present measurement system.

A Flexible Polymer Sensor for Light Point Localization

Abstract We present a flexible polymer sensor for light point localization based on the pyroelectric polymer poly(vinylidene fluoride) (PVDF) in combination with large area resistive electrodes. This large area sensor is simple in design; a division of the sensor surface into an array of individual sensor elements as used in active matrix technology is avoided. Electronic circuitry is placed only at the edges of the device. We have fabricated a flexible sensor strip with a length of 12 cm and a width of 1.6 cm according to the proposed concept. The position sensitive output signals of the sensor strip have been measured in response to the intensity-modulated light of a red laser diode. Two model-based normalization procedures have been developed in order to increase the quality of the measurement signals. The results indicate that the sensor strip can be treated mathematically analogous to a transmission line. Calculations based on the solutions of the telegrapher's equations under the appropriate boundary conditions are in good agreement with the experimental results, proving the suitability of the proposed concept for position sensitive detection.

Cationic photosensitive formulations based on silyl radical chemistry for green and red diode laser exposure

Download options Please wait... Article information DOI https://doi.org/10.1039/C1PY00460C Article type Paper Submitted 04 Oct 2011 Accepted 18 Nov 2011 First published 13 Dec 2011 Download Citation Polym. Chem., 2012,3, 1899-1902 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Cationic photosensitive formulations based on silyl radical chemistry for green and red diode laser exposure M. Tehfe, D. Gigmes, F. Dumur, D. Bertin, F. Morlet-Savary, B. Graff, J. Lalevée and J. Fouassier, Polym. Chem., 2012, 3, 1899 DOI: 10.1039/C1PY00460C To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Mohamad-Ali Tehfe Didier Gigmes Frédéric Dumur Denis Bertin Fabrice Morlet-Savary Bernadette Graff Jacques Lalevée Jean-Pierre Fouassier

A Compact Diode Laser Cavity Ring-Down Spectrometer for Atmospheric Measurements of NO<SUB>3</SUB> and N<SUB>2</SUB>O<SUB>5</SUB> with Automated Zeroing and Calibration

A compact rack-mounted cavity ring-down spectrometer (CRDS) for simultaneous measurements of the nocturnal nitrogen oxides NO(3) and N(2)O(5) in ambient air is described. The instrument uses a red diode laser to quantify mixing ratios of NO(3) (at its absorption maximum at 662 nm) and of N(2)O(5) following its thermal dissociation to NO(3) in a second detection channel. The spectrometer is equipped with an automated zeroing and calibration setup to determine effective NO(3) absorption cross-sections and NO(3) and N(2)O(5) inlet transmission efficiencies. The instrument response was calibrated using simultaneous measurements of NO(2), generated by thermal dissociation of N(2)O(5) and/or by titration of NO(3) with excess NO, using blue diode laser CRDS at 405 nm. When measuring ambient air, the (2σ, 10 s) precision of the red diode CRDS varied between 5 and 8 parts-per-trillion by volume (pptv), which sufficed to quantify N(2)O(5) concentrations under moderately polluted conditions. Sample N(2)O(5) measurements made on a rooftop on the University of Calgary campus in August 2010 are presented. A maximum N(2)O(5) mixing ratio of 130 pptv was observed, corresponding to a steady-state lifetime of less than 50 min. The NO(3) mixing ratios were below the detection limit, consistent with their predicted values based on equilibrium calculations. During the measurement period, the instrument response for N(2)O(5) was 70% of the theoretical maximum, rationalized by a slight mismatch of the laser diode output with the NO(3) absorption line and a N(2)O(5) inlet transmission efficiency less than unity. Advantages and limitations of the instrument's compact design are discussed.

The impact of cataract on the quantitative, non-invasive assessment of retinal blood Flow

The aim of the study was to determine the impact of cataract on the quantitative, non-invasive assessment of retinal blood flow assessed by bidirectional laser Doppler flowmetry and simultaneous vessel densitometry. Ten patients scheduled for extracapsular cataract extraction using phacoemulsification and intraocular lens implantation between the ages of 61 and 84 (mean age 73 years, SD ± 8) were prospectively recruited. Two visits were required to complete the study; one visit prior to extracapsular cataract extraction and one at least 6 weeks after the surgery to allow for sufficient postoperative recovery. The severity of cataract was documented using the Lens Opacity Classification System (LOCS, III) at the first visit. Retinal arteriolar hemodynamics were measured at both visits using the high-intensity setting of the Canon Laser Blood Flowmeter. All eyes showed no clinical signs of postoperative intraocular inflammation. The quantitative assessment of retinal arteriolar diameter and blood flow were reduced following extracapsular cataract extraction (Wilcoxon signed-rank test, p = 0.022 and p=0.028, respectively); however, centreline blood velocity was not significantly changed (Wilcoxon signed-rank test, p=0.074). Intraocular pressure was unchanged pre- and postcataract extraction. Retinal vessel densitometry assessment in the presence of cataract results in the erroneous elevation of the diameter measurement and thereby the calculation of blood flow. The bidirectional Doppler assessment of blood velocity appears to be more robust to light scatter induced by cataract. Care needs to be exercised in the interpretation of studies of retinal vessel diameter or blood flow that utilize similar densitometry techniques.

Novel color combiner composed of red, green, and blue laser diodes and a thermally expanded core fiber waveguide

We propose a new simple structure-based color combiner with red, green, and blue (RGB) laser diodes (LDs) and a thermally expanded core (TEC) fiber waveguide. As the color combiner used the LDs as optical sources, the total volume of the color combiner could be minimized as 3.84 cc and the output powers of RGB optical sources in the color combiner could be obtained efficiently as 10.324, 13.290, and 10.150 mW, respectively. A TEC fiber waveguide was used as a medium for color combination of RGB in the color combiner. As the TEC fiber waveguide was used as a key component for color combination, we could observe the color combiner had the degree of uniformity and the matching accuracy was good. The measured degree of uniformity and matching accuracy of RGB beams were 121 μm (in large diameter), 56 μm (in small diameter), and 109 μm (on x-axis), 20 μm (on y-axis), respectively.

The Effectiveness of Low‐Intensity Red Laser for Activating a Bleaching Gel and Its Effect in Temperature of the Bleaching Gel and the Dental Pulp

The effectiveness of low-intensity red laser for activating a bleaching gel and its effect in pulp temperature was not investigated in dental literature. The objective of this study was to assess the effectiveness of low-intensity red laser for activating a bleaching gel, as well as its effect in temperature of the bleaching gel and the dental pulp. Forty extracted bovine teeth were immersed in a solution of coffee 14 days for darkening. The initial colors were recorded by spectrophotometric analysis. The specimens were randomly distributed into two groups (N = 20): the control, which did not receive light and the experimental group that received light from an appliance fitted with three red light-emitting laser diodes (λ = 660 nm). A green-colored, 35% H(2) O(2) -based bleaching gel was applied for 30 minutes, and changed three times. After bleaching, the colors were again measured to obtain the L*a*b* values. Color variation was calculated (ΔE) and the data submitted to the non-paired t-test (5%). To assess temperature, 10 human incisors were prepared, in which one thermocouple was placed on the bleaching gel applied on the surface of the teeth and another inside the pulp chamber. There was a significant difference between the groups (p = 0.016), and the experimental group presented a significantly higher mean variation (7.21 ± 2.76) in comparison with the control group (5.37 ± 1.76). There was an increase in pulp temperature, but it was not sufficient to cause damage to the pulp. Bleaching gel activation with low-intensity red laser was capable of increasing the effectiveness of bleaching treatment and did not increase pulp temperature to levels deleterious to the pulp.

COMMENTARY. The Effectiveness of Low‐Intensity Red Laser for Activating a Bleaching Gel and Its Effect in Temperature of the Bleaching Gel and the Dental Pulp

Statement of the Problem: The effectiveness of low-intensity red laser for activating a bleaching gel and its effect in pulp temperature was not investigated in dental literature. Purpose: The objective of this study was to assess the effectiveness of low-intensity red laser for activating a bleaching gel, as well as its effect in temperature of the bleaching gel and the dental pulp. Materials and Methods: Forty extracted bovine teeth were immersed in a solution of coffee 14 days for darkening. The initial colors were recorded by spectrophotometric analysis. The specimens were randomly distributed into two groups (N = 20): the control, which did not receive light and the experimental group that received light from an appliance fitted with three red light-emitting laser diodes (λ = 660 nm). A green-colored, 35% H2O2–based bleaching gel was applied for 30 minutes, and changed three times. After bleaching, the colors were again measured to obtain the L*a*b* values. Color variation was calculated (ΔE) and the data submitted to the non-paired t-test (5%). To assess temperature, 10 human incisors were prepared, in which one thermocouple was placed on the bleaching gel applied on the surface of the teeth and another inside the pulp chamber. Results: There was a significant difference between the groups (p = 0.016), and the experimental group presented a significantly higher mean variation (7.21 ± 2.76) in comparison with the control group (5.37 ± 1.76). There was an increase in pulp temperature, but it was not sufficient to cause damage to the pulp. Conclusion: Bleaching gel activation with low-intensity red laser was capable of increasing the effectiveness of bleaching treatment and did not increase pulp temperature to levels deleterious to the pulp. CLINICAL SIGNIFICANCE The application of a low-intensity red laser was effective for activating a bleaching gel with green dye, without any deleterious increases in pulpal temperature. (J Esthet Restor Dent 24:126–134, 2012)

Pressure and temperature tuning of red laser diodes towards yellow and green

AbstractTwo InGaP/AlGaInP red laser diodes are studied at pressures up to 16 kbar and at temperatures down to 80 K. Emission wavelengths below 570 nm have been obtained, with low thresholds and high efficiencies. Pressure dependence of threshold currents is very different for the two lasers indicating that electron leakage occurs predominantly to L minima in one laser and to X minima in another laser.

The division and bending of green and red semiconductor laser light at the same time

In this experimental study, the laser light was split and bended using a specially designed glass lenses at the same time. This process has been done at the atmospheric pressure and room temperature conditions. During the experiments, the semiconductor laser as a source of green and red laser diode is used. In addition, polari- zation, magnetic field, electric field or any other auxiliary materials and systems which affect laser light are not used to bend the laser light. Only transparent glass lenses that are designed specially are used in the experimental study.

Laser-induced chlorophyll fluorescence and reflectance spectroscopy of cadmium treated Triticum aestivum L. plants

The present study deals with laser-induced chlorophyll fluorescence (LICF) spectra, reflectance spectra and fluores- cence induction kinetics (FIK) curves of Triticum aestivum L. plants treated with different concentrations of cadmium (0.01, 0.1 and 1.0 mM). LICF spectra were recorded in the region of 650-780 nm using violet diode laser (405 nm) and FIK curves were recorded at 685 and 730 nm using red diode laser (635 nm) for excitation. Reflectance spectra were recorded in the region of 400-800 nm using spectrophotometer with an integrating sphere. The fluorescence intensity ratios (FIR) were determined from LICF spectra, vitality index (Rfd) from FIK curves and narrow band vegetation index (NBVI) from reflectance spectra. These parameters along with plant growth parameters and photosynthetic pigment contents were used to analyze the effect of cadmium on wheat plants. The results clearly show that lower concentration of Cd (0.01 mM) shows stimulatory response; whereas higher concentrations (0.1 and 1.0 Mm) are hazardous for plant growth, photosynthetic pigments and photosynthetic activity of wheat plants.

Laser-induced chlorophyll fluorescence and reflectance spectroscopy of cadmium treatedTriticum aestivumL. plants

The present study deals with laser-induced chlorophyll fluorescence (LICF) spectra, reflectance spectra and fluorescence induction kinetics (FIK) curves ofTriticum aestivumL. plants treated with different concentrations of cadmium (0.01, 0.1 and 1.0 mM). LICF spectra were recorded in the region of 650–780 nm using violet diode laser (405 nm) and FIK curves were recorded at 685 and 730 nm using red diode laser (635 nm) for excitation. Reflectance spectra were recorded in the region of 400–800 nm using spectrophotometer with an integrating sphere. The fluorescence intensity ratios (FIR) were determined from LICF spectra, vitality index (Rfd) from FIK curves and narrow band vegetation index (NBVI) from reflectance spectra. These parameters along with plant growth parameters and photosynthetic pigment contents were used to analyze the effect of cadmium on wheat plants. The results clearly show that lower concentration of Cd (0.01 mM) shows stimulatory response; whereas higher concentrations (0.1 and 1.0 Mm) are hazardous for plant growth, photosynthetic pigments and photosynthetic activity of wheat plants.

Examination of the developed scanning system for red-green-blue laser projector with a feedback control

The galvanometric scanning system is widely used in laser material processing and laser shows. The scanner is a broadband component, damped sufficiently to operate over a wide range of frequencies, from zero to a higher value related to its mechanical resonance. Developing a galvanometric scanner is an important issue in the design of optical systems. This study focuses on the development of the scanning system for a laser projector using red, green, and blue diode lasers. The performance of the laser projector, which consists of the scanning control system, color control system, and position detector, is also discussed.

Laser-Induced Chlorophyll Fluorescence: A Technique for Detection of Dimethoate Effect on Chlorophyll Content and Photosynthetic Activity of Wheat Plant

Laser-induced chlorophyll fluorescence (LICF) spectra and fluorescence induction kinetics (FIK) curves of wheat plant leaves treated with different concentrations (50, 100 and 200 ppm) of dimethoate are recorded. LICF spectra are recorded in the region of 650-780 nm using violet diode laser (405 nm) and FIK curve at 685 and 730 nm with red diode laser (635 nm) for excitation. The fluorescence intensity ratios (FIR) are determined from LICF spectra and vitality index (R(fd)) from FIK curves. These parameters along with photosynthetic pigment contents and growth parameters are used to analyze the effect of dimethoate on wheat plants. The result indicates that lower concentration of 50 ppm shows stimulatory response while higher concentrations of dimethoate are hazardous for growth, photosynthetic pigments and activity of wheat plants.

Red Diode Laser in the Treatment of Epidermal Diseases in PDT

The process of laser absorption in the skin during laser irradiation was a critical point in medical application treatments. Delivery the correct amount of laser light is a critical element in photodynamic therapy (PDT). More amounts of laser light able to affect tissues in the skin and small amount not able to enhance PDT procedure in skin. The knowledge of the skin tone laser dependent distribution of 635 nm radiation and its penetration depth in skin is a very important precondition for the investigation of advantage laser induced effect in (PDT) in epidermis diseases (psoriasis). The aim of this work was to estimate an optimum effect of diode laser (635 nm) on the treatment of epidermis diseases in different color skin. Furthermore, it is to improve safety of laser in PDT in epidermis diseases treatment. Advanced system analytical program (ASAP) which is a new approach in investigating the PDT, dependent on optical properties of different skin color was used in present work. A two layered Realistic Skin Model (RSM); stratum corneum and epidermal with red laser (635 nm, 10 mW) were used for irradiative transfer to study fluence and absorbance in different penetration for various human skin colors. Several skin tones very fair, fair, light, medium and dark are used to irradiative transfer. This investigation involved the principles of laser tissue interaction when the skin optically injected by a red laser diode. The results demonstrated that the power characteristic of a laser diode (635 nm) can affect the treatment of epidermal disease in various color skins. Power absorption of the various human skins were recorded and analyzed in order to find the influence of the melanin in PDT treatment in epidermal disease. A two layered RSM show that the change in penetration depth in epidermal layer of the color skin has a larger effect on the distribution of absorbed laser in the skin; this is due to the variation of the melanin concentration for each color. Keywords—Photodynamic therapy, Realistic skin model, Laser, Light penetration, simulation, Optical properties of skin, Melanin.

Production of Reactive Oxygen Species from Photosensitizers Activated with Visible Light Sources Available in Dental Offices

The aim of this study was to assess the ability of commonly available red- or blue-light dental sources to generate reactive oxygen species (ROS) from photosensitive chemicals that might be useful for photodynamic antimicrobial chemotherapy (PACT). Although the use of red diode lasers is well documented, there is limited information on how useful blue-light sources might be for PACT in dental contexts. A diode laser (Periowave; see Table 1 for material and equipment sources) emitting red light (660-675 nm) was used to activate toluidine blue; riboflavin and pheophorbide-a polylysine (pheophorbide-a-PLL) were photoactivated using an Optilux 501 curing unit emitting blue light (380-500 nm). Ozone gas (generated by OzoTop, Tip Top Tips, Rolle, Switzerland), sodium hypochlorite, and hydrogen peroxide were used for comparison. ROS production was estimated using an iodine-triiodide colorimetric assay, and ROS levels were plotted versus concentration of chemicals to determine each chemical's efficiency in ROS production. One-way ANOVA with Tukey post hoc analysis (alpha = 0.05) was used to compare the efficiencies of ROS production for the various chemicals. Sodium hypochlorite, hydrogen peroxide, and ozone gas produced ROS spontaneously, whereas pheophorbide-a-PLL, riboflavin, and toluidine blue required light exposure. The efficiency of ROS production was higher for pheophorbide-a-PLL and toluidine blue than for ozone gas or riboflavin (p < 0.05). Hydrogen peroxide was the least efficient ROS producer. The results of the current study support the use of blue- or red-light-absorbing photosensitizers as candidates to produce ROS for clinical applications. Blue-light photosensitizers were as efficient as red-light photosensitizers in producing ROS and more efficient than the oxidant chemicals currently used for dental disinfection.

On ternary nitride substrates for visible semiconductor light-emitters

No nitride or other substrate material exists for growing lattice-matched nitride device structures. Use of bulk GaN or sapphire substrates is complicated by lattice and thermal mismatches that lead to defect and dislocation generation. To alleviate this problem, we recently proposed ternary nitride substrates on which lattice-matched structures could be grown for lasers within specified spectral bands. These proposed application-oriented nitride substrates have one drawback: several would be required to cover the visible spectrum. By taking advantage of the complex (but feature-rich) valence band structure of nitrides, we have determined that a single substrate (In0.15Ga0.85N) could be used for the development of efficient blue, green, and red laser diodes.