Photoluminescence and Photocurrent from InGaN/GaN Diodes with Quantum Wells of Different Widths and Polarities.

We compare the optical properties of four diode samples differing by built-in field direction and width of the InGaN quantum well in the active layer: two diodes with standard layer sequences and 2.6 and 15 nm well widths and two diodes with inverted layer ordering (due to the tunnel junction grown before the structure) also with 2.6 and 15 nm widths.

Evidence for "dark charge" from photoluminescence measurements in wide InGaN quantum wells.

Wide (15-25 nm) InGaN/GaN quantum wells in LED structures were studied by time-resolved photoluminescence (PL) spectroscopy and compared with narrow (2.6 nm) wells in similar LED structures. Using below-barrier pulsed excitation in the microsecond range, we measured increase and decay of PL pulses.

Blue Laser (450 nm) Treatment of Solar Lentigines.

This study tested a blue light source for the treatment of solar lentigines. A total of 14 patients with solar lentigines were treated with radiation from a novel, high-power 450 nm blue laser that was created for this project. The group contained eight patients with solar lentigines on the face, two patients with the lesions on the dorsal of the hands, and four patients with the lesions on the trunk and forearms.

Fractal Dimension and Texture Analysis of Lesion Autofluorescence in the Evaluation of Oral Lichen Planus Treatment Effectiveness.

Background: Oral Lichen planus (OLP) is a chronic inflammatory disease. Topical steroids are used as the treatment of choice. The alternative is photodynamic therapy (PDT).

Blue Laser (450 nm) in the Treatment of Port Wine Stains and Telangiectasia.

This study aimed to test a blue light source for the treatment of port wine stains (PWS) and telangiectasia and to compare this with the application of green and yellow lasers based on data in the literature. A total of 22 patients with PWS were treated with radiation from a novel, high-power 450 nm blue laser that was created for this project. The group contained 15 patients with red PWS and 7 with pink PWS.

Quantum-confined Stark effect and mechanisms of its screening in InGaN/GaN light-emitting diodes with a tunnel junction.

Nitride-based light-emitting diodes (LEDs) are well known to suffer from a high built-in electric field in the quantum wells (QWs). In this paper we determined to what extent the electric field is screened by injected current. In our approach we used high pressure to study this evolution.

Assessment of Human Gingival Fibroblast Proliferation after Laser Stimulation In Vitro Using Different Laser Types and Wavelengths (1064, 980, 635, 450, and 405 nm)-Preliminary Report.

Purpose: to assess the effect of photobiomodulation (PBM) on human gingival fibroblast proliferation.

Methods: The study was conducted using the primary cell cultures of human fibroblasts collected from systemically healthy donors. Three different laser types, Nd:YAG (1064 nm), infrared diode laser (980 nm), and prototype led laser emitting 405, 450, and 635 nm were used to irradiate the fibroblasts.

Assessment of Effects of Laser Light Combining Three Wavelengths (450, 520 and 640 nm) on Temperature Increase and Depth of Tissue Lesions in an Ex Vivo Study.

Background: Lasers are widely used in medicine in soft and hard tissue surgeries and biostimulation. Studies found in literature typically compare the effects of single-wavelength lasers on tissues or cell cultures. In our study, we used a diode laser capable of emitting three components of visible light (640 nm, red; 520 nm, green; 450 nm, blue) and combining them in a single beam.

Photodynamic diagnosis and photodynamic therapy in basal cell carcinoma using a novel laser light source.

The aim of the present study was evaluating the effects and safety of new laser light source in PDD and PDT of basal cell carcinoma, BCC. The patients presented challenging localizations of the tumor or tumor combined with Gorlin syndrome. The PDD and PDT was performed in 50 patients with 54 histologically confirmed BCCs.

Anomalous photocurrent in wide InGaN quantum wells.

We show that in a wide InGaN quantum well, placed within an undoped region of the pin diode, a photocurrent in the forward direction is observed. The photocurrent switches to reverse direction when the light intensity is increased and/or photon energy is above the bandgap of the quantum barrier. We propose a model showing that the anomalous photocurrent is due to the fact that when the carriers are pumped into the wide quantum well they cannot recombine until the built-in field is screened.

Assessment of in vivo experiments: The newly synthesized porphyrin with proper light source enhanced effectiveness of PDT comparing to 5-ALA-mediated PDT.

Background: The search for new photosensitizers for application in photodynamic therapy has quite a long history. In the past, a large number of potent photosensitizers were used in both basic and clinical studies; however, only a few turned out to be effective and safe.

Methods: In the present study, two compounds were used: 5-aminolevulinic acid in two formulations (free and liposomal), and the newly synthesized porphyrin, 5,10,15,20-tetra-p-tolyl-22,24-dithiadibenzocarbaporphyrin, termed DTDB.

Note: Photoluminescence excitation measurements in the 1.1-1.6 μm spectral range.

Pressure-tuned laser diodes are used for photoluminescence excitation in quantum-well samples grown on InP. With two bent-waveguide, external cavity lasers, the spectral range from 1.1 to 1.

Photoluminescence excitation measurements using pressure-tuned laser diodes.

Pressure-tuned laser diodes in external cavity were used as tunable sources for photoluminescence excitation (PLE) spectroscopy. The method was demonstrated in the 720 nm-1070 nm spectral range using a few commercial laser diodes. The samples for PLE measurements were quantum-well structures grown on GaAs and on InP.

Pressure tuning of laser diodes in the near-infrared up to 1850 nm: operational characteristics and reliability studies.

Wavelength tuning of infrared laser diodes in the high-hydrostatic pressure setup is demonstrated and its reliability is discussed in detail. Major reliability issues concern the photochemical reactions on the laser facet and the presence of strong absorption bands above 1650 nm in typical pressure liquids that do not undergo phase transitions up to 20 kbar. Despite these difficulties spectrally wide-range pressure tuning can be achieved with sufficient reliability for spectroscopic applications.

Gradient index collimator lens for high pressure applications.

A modified gradient index (GRIN) lens is optimised for use in a liquid-type high pressure cell. It was found that high pressure changes the optical power of the gradient-index lenses by changing the index profile of the glass. In this paper, we present a modified GRIN lens in which these changes are compensated by the pressure-induced changes of the refraction index of the liquid used as a pressure medium.

Note: Coupling of multiple laser diodes into a multi-mode fiber.

Diode lasers are coupled to a multi-mode fiber (with 100-400 μm core) using a reflector in the form of a regular pyramid. The optimization of the optical setup allows to couple 60%-90% of light into the fiber. The demonstrator achieves 3.

Trisomy 22pter-q12.3 presenting with hepatic dysfunction variability of cat-eye syndrome.

We describe the clinical characteristics of two patients with cat-eye syndrome (CES, MIM #115470) resulting from a supernumerary marker chromosome that includes 22pter-q12.3. They both presented a constellation of features typical of CES, including coloboma, auricular malformations, heart and renal anomalies, as well as hepatic dysfunction, which led to severe effects.