Visible Red Light Research Articles

High power red and near-IR generation using four wave mixing in all integrated fibre laser systems

We demonstrate high power generation of visible red and near IR light by four wave mixing in photonic crystal fibres (PCFs) pumped at 1064 nm with picosecond pulses (30 - 80 ps). 30% conversion efficiency is demonstrated in a single pass using fibre lengths less than 1 m, with signal wavelengths from 650 nm to 820 nm selectable by choice of PCF. An all fibre integrated system delivers 2.16 W at 740 nm with a pulse repetition frequency of 20 MHz. We discuss the overall parameter space for this type of wavelength conversion in PCF with different fibre designs suitable for delivering a particular wavelength at low or high power.

PREPARATION OF LUMINESCENT MATERIALS BaMoO_4:Eu~(3+) BY HIGH TEMPERATURE BALL MILLING

BaMoO_4:Eu~(3+)phosphors were synthesized by high temperature ball milling method and using(NH_4)_6Mo_7O_(24)·4H_2O,BaCO_3 and Eu_2O_3 as raw materials.Crystalline phases,morphology and luminescent properties of sample were characterized by XRD,SEM and emission spectra. XRD patterns indicated that a single phase of BaMoO_4:Eu~(3+)can be obtained by 4 h ball milling at 600℃,with 15%Eu~(3+)(mole fraction)dopped concentration.Photolumincence experiment results showed that the emission is a line spectrum and the main peak is located at visible red light (616 nm).The synthesized temperature was decreased about 400℃while the dopped Eu~(3+)concentration was increased about 7%than those of chemical deposited method.The BaMoO_4:Eu~(3+)powders has considerable luminescent intensity prepared under the optimum technological conditions.In the high temperature ball milling process,the cooperation action of milling and temperature,significantly increased the activation energy of the reaction system.

Probabilistic atlas can improve reconstruction from optical imaging of the neonatal brain

Diffuse optical imaging is an emerging medical imaging modality based on near-infrared and visible red light. The method can be used for imaging activations in the human brain. In this study, a deformable probabilistic atlas of the distribution of tissue types within the term neonatal head was created based on MR images. The use of anatomical prior information provided by such atlas in reconstructing brain activations from optical imaging measurements was studied using Monte Carlo simulations. The results suggest that use of generic anatomical information can greatly improve the spatial accuracy and robustness of the reconstruction when noise is present in the data.

Effect of laser on the bone defects healing in rats: An experimental study

Introduction. The stimulating effect of low-power laser on the process of wound healing is characterized by proliferation of fibroblasts, collagen production, and enhanced enzyme activity. The aim of this study was to evaluate the possible enhancing effect of low-power laser on the rate of the healing artificially created osseous defects in rats. Material and methods. Ten albino Wister rats were involved in this experimental study. Round defects (3 mm wide 2 mm deep) were made in each rat on both femurs. The right side was experimental while the left side was control. Osseous defects on the experimental side were daily treated with Galium, Aluminium, Arsenid (GaAlAs) low-power laser (Medicolaser 637, Technoline, Belgrade, Serbia), at the energy output of 4 J/cm2, with constant power density of 50 mW, and a wave length 637 nm (visible red light) per defect during seven days. Defects on the control side healed spontaneously. The effects of laser were evaluated two and three weeks postoperatively. Results. Histological analysis showed the powerful osteoblastic activity on the bone defects of the experimental side two weeks after surgery. On the control side, a new bone formation was noticed at the periphery of the bone defects but fibroblastic tissue with no signs of new bone was presented in the central areas. Three weeks after surgery, on the experimental side, bone defects were completely filled with spongious, lamellar bone while non-treated bone defects were characterized by mature lamellar bone at the peripheral areas and immature bone at the central areas. Conclusion. The results showed that the use of low-power laser could have a significant influence on the speed of curing bone defects in rats. <br><br><font color="red"><b> This article has been retracted. Link to the retraction <u><a href="http://dx.doi.org/10.2298/SGS1002001U">10.2298/SGS1002001U</a></u></b></font>

Influence of gallium and alkali halide addition on the optical and thermo–mechanical properties of GeSe2-Ga2Se3 glass

A systematic compositional study of a new family of chalcogenide glasses, transparent from the visible range up to 16 μm has been performed. Numerous glass forming regions were explored in the GeSe2-Ga2Se3-MX system (MX = alkali halide) in order to understand the role of alkali halides and the effect of Ga substitution for Sb in the glass structure. To that avail, several ternary diagrams were investigated, and optical and thermo-mechanical measurements were performed. It is shown that the introduction of an alkali halide in the GeSe2-Ga2Se3 glasses increased the band-gap energy Eg by stabilizing electrons from the lone pairs of selenium. However, the glass hardness was lowered due to a decrease in the glass network reticulation. The chemical resistance was studied in a glass containing high CsCl content. Significant corrosion occurred when the glass was exposed to hot water for several hours. There is a great deal of interest in these glasses for use in thermal imaging devices, as they permit the alignment of infrared optical systems with visible red light. Furthermore, the low cost of raw materials and the possibility of shaping these glasses into lenses by molding could extend their utilization from defense to civilian applications.

Correlation between luminescence and structural evolution of Si-rich silicon oxide film annealed at different temperatures

The visible red band light emission of the Si-rich silicon oxide films prepared by electron-beam evaporation with postannealing was investigated. The films annealed at temperatures lower than 600°C were composed of Si nanoclusters with high fraction of boundary atoms, featuring photoluminescence (PL) band centered at 700–710nm. By contrast, the PL bands of the films annealed at temperatures higher than 600°C redshifted with the expansion of the Si nanoclusters. The most intense light emission was observed in the 600°C annealed sample. The conversion of the luminescence mechanism from surface states controlled to quantum confinement controlled was proposed on the basis of the evolution of the film structure.

Free-Space Optical communication using visible light

The possibility of visible red light laser being used as signal light source for Free-Space Optical (FSO) communication is proposed. Based on analysis of transmission in atmospheric channel concerning 650 nm laser beam, performance of wireless laser communication link utilizing a low power red laser diode was evaluated. The proposed system can achieve a maximum range of 300 m at data rate 100 Mb/s theoretically. An experimental short-range link at data rate 10 Mb/s covering 300 m has been implemented in our university. It is feasible to enhance the system performance such as link range and data rate by increasing transmitting power and decreasing laser beam divergence angle or through other approaches.

Synchrotron radiation x-ray beam profile monitor using chemical vapor deposition diamond film

Photoluminescence (PL) of a Si-doped polycrystalline diamond film fabricated using the chemical vapor deposition technique was employed to measure the profile of a synchrotron radiation pink x-ray beam emitted from an in-vacuum hybrid undulator at the SPring-8 facility. The spectrum of the section of the diamond film penetrated by the emitted visible red light exhibited a peak at 739nm and a wideband structure extending from 550to700nm. The PL intensity increased with the absorbed dose of the incident beam in the diamond within a dynamic range of 103. A two-dimensional distribution of the PL intensity revealed the undulator beam profile.

3D-CT imaging using characteristic X-rays and visible lights produced by ion micro-beam bombardment

We improved the spatial resolution of a 3D-CT imaging system consisting of a micro-beam and an X-ray CCD camera of 1 mega pixels (Hamamatsu photonics C8800X), whose element size is 8μm×8μm providing an image size of 8mm×8mm. A small ant of ∼6mm body length was placed in a small tube, rotated by a stepping motor, and a spatial resolution of 4μm for X-ray micron-CT using characteristic Ti-K-X-rays (4.558keV) produced by 3MeV proton micro-beams was obtained. We applied the X-ray micron-CT to a small ant’s head and obtained the fine structures of the head’s interior. Because the CCD is sensitive to visible light, we also examined the capability of light micron-CT using visible red light from an Al2O3(Cr) ruby scintillator and applied the micron-CT to a small red tick. Though the red tick is highly transparent to Ti-K-X-rays, visible red light does not penetrate through the red tick. The most serious problem was dispersion of lights due to Thomson scattering resulting in obscure projection images.

Light-emitting Diode Phototherapy at 630.+-.3 nm Increases Local Levels of Skin-homing T-cells in Human Subjects

Red light phototherapy with laser sources has been used successfully for a number of indications. A new generation of quasimonochromatic 630 +/- 3 nm light-emitting diode (LED) systems has recently been yielding good results for the same indications, but no study has examined changes in visible red light irradiated skin at an immunological level. This study was thus designed to examine changes in skin-homing T-cell levels induced in normal human skin by visible red LED energy. Six adult male volunteers (35 approximately 48 years old) who satisfied all study criteria had the skin over the lateral aspect of the leg irradiated once per week for 8 weeks with a visible red (630 +/- 3 nm) LED-based system, with irradiance of 105 m/cm2, 15 minutes/session, and a radiant flux of 94 J/cm2. Skin biopsies were performed after the eighth treatment session, and cultures were prepared to assay the type and quantity of skin-homing T-cells using qualitative and quantitative polymerase chain reaction (PCR) techniques. Ultrastructural changes were also assessed with transmission electron microscopy. Transmission electron microscopy revealed mild fibroplastic changes in fibroblasts, with no acute inflammatory changes throughout the treatment session. Qualitative PCR showed the presence of both Th-1 and Th-2 T-cells, and quantitative PCR showed an increase in the numbers of both types of skin-homing T-cells, much more so for Th-2 than for Th-1. Visible red LED irradiation appears to activate the skin-homing immune system.

Photodynamic Therapy: Potential Applications for Exotic Animal Oncology

Photodynamic therapy (PDT) is a novel form of treatment for solid cancers. It relies on the systemic administration of a light-reactive drug (photosensitizer) to the patient. Through various mechanisms, the photosensitizer localizes to the malignant tissue. The photosensitizer is then activated by visible red light, often provided by a laser. The drug and light alone do not cause tissue damage; when the photosensitizer, light, and molecular oxygen are present together, the reactive oxygen species generated locally lead to apoptosis, vascular stasis, and subsequent ischemic necrosis, and inflammation. PDT is potentially useful for the treatment of exotic animals, because it has fewer adverse effects than radiation therapy or chemotherapy. Because PDT is typically a single session, there are fewer issues with repeated general anesthesia and vascular access. To date, experiences with PDT in exotic animals are limited, but preliminary reports suggest it will become a useful treatment in these species. Further knowledge of photosensitizer pharmacokinetics and tumor biology in exotic animals will be necessary to develop PDT into a useful cancer treatment modality.

Photodynamic Therapy: Potential Applications for Exotic Animal Oncology

Photodynamic therapy (PDT) is a novel form of treatment for solid cancers. It relies on the systemic administration of a light-reactive drug (photosensitizer) to the patient. Through various mechanisms, the photosensitizer localizes to the malignant tissue. The photosensitizer is then activated by visible red light, often provided by a laser. The drug and light alone do not cause tissue damage; when the photosensitizer, light, and molecular oxygen are present together, the reactive oxygen species generated locally lead to apoptosis, vascular stasis, and subsequent ischemic necrosis, and inflammation. PDT is potentially useful for the treatment of exotic animals, because it has fewer adverse effects than radiation therapy or chemotherapy. Because PDT is typically a single session, there are fewer issues with repeated general anesthesia and vascular access. To date, experiences with PDT in exotic animals are limited, but preliminary reports suggest it will become a useful treatment in these species. Further knowledge of photosensitizer pharmacokinetics and tumor biology in exotic animals will be necessary to develop PDT into a useful cancer treatment modality.

Visible red light emission from Eu‐doped GaN quantum dots grown by plasma‐assisted MBE

We demonstrate the growth of GaN quantum dots doped with Eu by plasma-assisted MBE. Intense emission from the intra-atomic 4f transition of Eu3+ was observed at 622 nm. GaN quantum dots (QDs) doped with 1% Eu showed the maximum emission. The full-width at half maximum (FWHM) of the CL spectrum of Eu-doped GaN QDs was 2.1 nm at room temperature. Eu doping increased the size of QDs by 4 times and decreased the density of QDs by one order of magnitude. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Photoinactivation of vesicular stomatitis virus by a photodynamic agent, chlorophyll derivatives from silkworm excreta

The efficacy of chlorophyll derivatives from silkworm excreta (CpD) in photodynamic antimicrobial chemotherapy (PACT) was studied. An enveloped animal virus, vesicular stomatitis virus (VSV), was used as a target organism. For CpD mediated PACT, the viruses in suspensions were treated with various doses of CpD (15–60 μg/ml) and visible red light was fixed at 120 mJ/cm 2. The antiviral effect of the CpD-PACT was measured 1 h after light irradiation by the extent of suppression of plaque forming units (pfu). In cultures inoculated with PACT-treated VSV, suppression of pfu was prominent and the results were demonstrated in a dose-dependent manner. In assays of RT-PCR, a single dose of 30 μg/ml CpD and light caused complete inhibition of viral RNA synthesis in the host cells, which agreed with the complete loss of plaque forming activity observed in pfu assays. An in vitro transcription assay for viral RNA using [ 3H]UTP and gel electrophoresis for the level of M protein was conducted. A gradual decrease in viral RNA transcription and an immediate decrease in M protein levels were observed in cells inoculated with the CpD-PACT-treated virus. These results demonstrated that CpD is a potential photodynamic antiviral agent, which causes inactivation of the matrix protein as well as transcription mechanisms involved in VSV replication.

A9. Excess hair: physical and pharmacological treatments

The growth of unwanted hair can be aesthetically distressing and may psychologically affect both women and men. For centuries, numerous techniques have been employed for this indication.1 Modern medicine has developed effective physical and pharmacological methods for the removal of unwanted hair. Laser technology and the principle of selective photothermolysis offers a new approach.2 Pigmented hair bulbs selectively absorb pulsed laser light of wavelenghts ranging from visible red light to low infrared. Light converts to heat and thermally damages the pigmented hair bulb without affecting the surrounding tissue. The follicular epithelium regenerates slowly and regrowth may occur. Nevertheless, the new hair will be thinner and softer. Depending on the anagen/telogen ratio of various body sites, two or more treatment sessions are required. Pharmacological hair reduction can be achieved by long-term treatment with antiandrogens or may be based on blocking of the mitotic activity of the follicular epithelium. Eflornithine, in a 13.9% cream preparation thinly applied twice daily, blocks ornithine decarboxylase, an enzyme needed for the synthesis of polyamines, the main source of the hair shaft.3 Following an average of 2 treatment sessions with the diode laser, sufficient reduction of pigmented hair can be achieved for a mean period of 8 months. Applied topically, Eflornithine is able to reduce the growth of pigmented or unpigmented hair to an extent of at least 50% when applied over a longer period. Compared with conventional mechanical, chemical, and other physical epilatory procedures, modern hair reduction – either laser assisted or pharmacologically-based – represents highly effective treatment options for the reduction of unwanted hair growth.

Phase matching of rutile single crystal

Phase matching for the third-harmonic generation (THG) of rutile single crystal (110) at 1.9 μm has been investigated. THG with a visible red light (633 nm) was clearly observed, indicating that TiO2 (rutile) is one of the most promising third-order nonlinear optical materials.

Q-Switched Ruby Laser Treatment of Congenital Nevi

The Q-switched ruby laser has been used to treat a number of cutaneous lesions, including lentigines, 1 tattoos, and nevus of Ota. 2 The Q-switched ruby laser emits visible red light with a wave-length of 694 nm and pulse duration of 28 to 40 nanoseconds. This relatively long wavelength and short pulse duration allow for the absorption of laser energy into the dermis with minimal textural changes. Laser energy is selectively absorbed by both keratinocytes and melanocytes containing melanosomes. Although melanin in these melanosomes has an absorption spectrum that is highest in the UV range, diminishing toward the infrared range, there is minimal competitive absorption of ruby energy (694 nm) by oxyhemoglobin. 3 Management of congenital nevi has been the subject of much debate over the past decade. This stems from the unresolved controversy concerning their potential for malignant degeneration, specifically to malignant melanoma. We report on the use

A light-reflectance meter to quantify silvering during smolting in Atlantic salmon

An easy-to-construct apparatus is described to quantify changes in silvering during smolting. A modulated visible-red light emitter/receiver unit converts light reflected from the flank of the fish into a DC voltage, the voltage being proportional to the intensity of the reflected light.

Platin(II)‐Komplexe mit Porphyrinliganden: Synthese und Synergismen bei der photodynamischen Tumortherapie

Platinum(II) Complexes with Porphyrin Ligands: Synthesis and Synergisms in the Photodynamic Tumor TherapyTwelve porphyrin ligands (2–5, 8, 13–16, 19, 27, 28) and their platinum(II) complexes (29–40) were synthesized and characterized. Nine of the porphyrins are derived from hemin, and three are based on tetraphenylporphyrin. The ligands were transformed into diammine‐dicarboxylatoplatinum(II) complexes and diamine‐dichloroplatinum(II) complexes. The antitumor activity in the photodynamic therapy of the ligands and their complexes was tested in vitro towards the MDA‐MB‐231 mammary carcinoma cell line. The results obtained showed an additive effect of the photodynamic activity of the porphyrin skeleton when irradiated with visible red light and the cytotoxic activity of the platinum moiety in the complexes.

EFFECTS OF LIGHT ON T‐CELLS IN HIV‐INFECTED SUBJECTS ARE NOT DEPENDENT ON HISTORY OF SEASONAL AFFECTIVE DISORDER

In order to evaluate the effect of light on helper- and suppressor-T-cell counts in HIV-infected individuals, with and without a history of seasonal affective disorder (SAD), we treated 35 subjects with 45 min of light therapy in the morning, in a crossover design involving two 2 week treatment conditions: visible white light (half-peak band width, 530-620 nm; 10,000 lux) and visible red light (half-peak band width, 615-685 nm; 175 lux). We found small but significant differences between the two treatment conditions, with higher CD4 and CD8 levels during the white, as compared with the red, condition. There were no differences between baseline and treatment conditions. Both light treatment conditions were associated with significant mood improvements in the SAD, but not the non-SAD, subjects. There was no evidence that the higher cell counts seen under the bright light conditions were mediated by the effects of light on mood or on plasma cortisol levels. While the size of the light effect on T-cells renders questionable the potential therapeutic value of this treatment modality for HIV, the finding is of theoretical interest and is reassuring for those HIV-infected individuals who require light treatment for other reasons.