A New Ex Vivo Human Skin Burn Model

Currently, most burn models for preclinical testing are on animals. For obvious ethical, anatomical, and physiological reasons, these models could be replaced with optimized ex vivo systems. The creation of a burn model on human skin using a pulsed dye laser could represent a relevant model for preclinical research. Six samples of excess human abdominal skin were obtained within one hour after surgery. Burn injuries were induced on small samples of cleaned skin using a pulsed dye laser on skin samples, at varying fluences, pulse numbers and illumination duration. In total, 70 burn injuries were performed on skin ex vivo before being histologically and dermato-pathologically analyzed. Irradiated burned skin samples were classified with a specified code representing burn degrees. Then, a selection of samples was inspected after 14 and 21 days to assess their capacity to heal spontaneously and re-epithelize. We determined the parameters of a pulsed dye laser inducing first, second, and third degree burns on human skin and with fixed parameters, especially superficial and deep second degree burns. After 21 days with the ex vivo model, neo-epidermis was formed. Our results showed that this simple, rapid, user-independent process creates reproducible and uniform burns of different, predictable degrees that are close to clinical reality. Human skin ex vivo models can be an alternative to and complete animal experimentation, particularly for preclinical large screening. This model could be used to foster the testing of new treatments on standardized degrees of burn injuries and thus improve therapeutic strategies.

Effect of Laser and Energy-based Device Therapies to Minimize Surgical Scar Formation: A Systematic Review and Network Meta-analysis

Utilization of lasers and energy-based devices for surgical scar minimization has been substantially evaluated in placebo-controlled trials. The aim of this study was to compare reported measures of efficacy of lasers and energy-based devices in clinical trials in preventing surgical scar formation in a systematic review and network meta-analyses. Five electronic databases, PubMed, Scopus, Embase, ClinicalTrials.gov, and the Cochrane Library, were searched to retrieve relevant articles. The search was limited to randomized controlled trials that reported on clinical outcomes of surgical scars with treatment initiation no later than 6 months after surgery and a follow-up period of at least 3 months. A total of 18 randomized controlled trials involving 482 participants and 671 postsurgical wounds were included in the network meta-analyses. The results showed that the most efficacious treatments were achieved using low-level laser therapy) (weighted mean difference -3.78; 95% confidence interval (95% CI) -6.32, -1.24) and pulsed dye laser (weighted mean difference -2.46; 95% CI -4.53, -0.38). Nevertheless, low-level laser therapy and pulsed dye laser demonstrated comparable outcomes in surgical scar minimization (weighted mean difference -1.32, 95% CI -3.53, 0.89). The findings of this network meta-analyses suggest that low-level laser therapy and pulsed dye laser are both effective treatments for minimization of scar formation following primary closure of surgical wounds with comparable treatment outcomes.

Efficacy and safety of 595-nm pulsed dye laser treating port wine stains in Vietnamese patients: analysis of 124 cases and optimal treatment regimens

The purpose of this study is to determine the efficacy and safety of 595-nm pulsed dye laser (PDL) for port wine stains (PWS) treatment in Vietnamese patients. The study also analyzed the association between the response to treatment and the characteristics of patients and treatment regimens. Parallelly, the study contributed to further optimal treatment sessions for different subjects based on the data collected. One hundred twenty-five patients who underwent 595-nm PDL to treat PWS were included in the study, in which data from 124 patients was retrospectively analyzed. Data on demographic characteristics of patients, treatment regimens, and clinical improvement were collected. SPSS version 25 was used to analyze the relationship between associated factors and the response rate. The overall response rate of Vietnamese patients who had Fitzpatrick skin classification type III and IV was 73.4%. Age, gender, treatment sessions, and lesion positions were generally not associated with the response rate. The lesion grade was the sole element that affected the clinical improvement. The lesion grade 1 had the best response (100%) even after a short duration of treatment (six to ten treatments). Lesion grade 4 demanded over 16 treatments to reach > 60% of improvement. The lesion grades 1 and 2 could be blanched with regimen < 10 treatments while regimens exceeding 15 treatments should be carefully considered for lesions at grade 3 after evaluating associated conditions. Lesions at grade 4 demanded ≥ 16 treatments to reach acceptable outcomes. These results could help physicians establish a reasonable treatment strategy for patients.

Dual optofluidic distributed feedback dye lasers for multiplexed biosensing applications

Integrated optofluidic devices have become subjects of high interest for rapid biosensor devices due to their unique ability to combine the fluidic processing of small volumes of microfluidics with the analysis capabilities of photonic structures. By integrating dynamically reconfigurable optofluidic lasers on-chip, complex coupling can be eliminated while further increasing the capabilities of sensors to detect an increasing number of target biomarkers. Here, we report a polydimethylsiloxane-based device with two on-chip fluidic distributed feedback (DFB) laser cavities that are integrated with an orthogonal analyte channel for multiplexed fluorescence excitation. One DFB grating is filled with 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran dissolved in dimethyl sulfoxide. The second grating is filled with rhodamine 6G dissolved in a diluted ethylene glycol solution. We present characterization of both lasers through analysis of the lasing spectra for spectral narrowing along with a power series to observe threshold behavior. We then demonstrate simultaneous detection of two different fluorescent microbeads as a proof of concept for scalable, single biomarker analysis using on-chip optofluidic lasers.

Update on lasers in pediatric dermatology: how primary care providers can help patients and families navigate appropriate treatment options and timelines

PURPOSE OF REVIEW

The use of lasers in pediatric dermatology is well established, but recent literature has expanded the evidence for specific timelines of treatment. Additionally, new devices and combinations with medical therapy have improved outcomes and treatment options for various conditions.

RECENT FINDINGS

Pulsed dye laser remains the first-line laser for vascular lesions. Recent guidelines support early initiation of laser treatment in port-wine birthmarks to optimize outcomes. For hemangiomas, laser treatment can offer a meaningful addition to oral propranolol therapy. Lasers with shorter wavelengths offer improved outcomes with decreased downtime for pigmented lesions. General anesthesia in the pediatric population continues to be a controversial topic, and the decision to perform laser under general versus topical anesthesia requires discussion with family of risks and benefits.

SUMMARY

Primary care providers can benefit their patients by prompt referral to dermatology for discussion of laser treatment. Port-wine birthmarks require referral in the first weeks of life so that laser treatment can be initiated if appropriate. Although many dermatologic conditions cannot be completely cleared or cured with laser, treatment can offer meaningful outcomes and benefit for patients and families.

Surfactant mediated suppression of aggregation and excited state ring puckering process in Pyrromethene 597-Application in water based dye laser

Water is being considered as an economical, safe and environmental friendly alternative solvent for dye lasers. However, the use of water in dye laser is restricted due to the formation of non-emissive aggregates of dye molecules. In the present study we have explored the possibility of the use of commercially available surfactant molecules for the water based laser of Pyrromethene 597 (PM597) dye, which has emerged as an alternative for more commonly used Rhodamine dyes in dye laser systems. Our studies show that in water, PM597 forms non-emissive aggregates which can be dissociated into monomeric dye molecules by adding common surfactants. Further, the high microviscosity in the micellar media retarded energy wasting ring puckering process in the excited state of the dye leading to the increase in its emission yield and excited state lifetime to a significant extent. It has been demonstrated that the emission yield and excited state lifetime in surfactant solution is relatively higher than in ethanol, the most commonly used organic solvent for dye lasers. Lasing action has been demonstrated in the aqueous solution of dye and lasing efficiency is found to be comparable to ethanol.

In Vivo Dual-Modal Photoacoustic and Ultrasound Imaging of Sentinel Lymph Nodes Using a Solid-State Dye Laser System

Photoacoustic imaging (PAI) is being actively investigated as a non-invasive and non-radioactive imaging technique for sentinel lymph node (SLN) biopsy. By taking advantage of optical and ultrasound imaging, PAI probes SLNs non-invasively with methylene blue (MB) in both live animals and breast cancer patients. However, these PAI systems have limitations for widespread use in clinics and commercial marketplaces because the lasers used by the PAI systems, e.g., tunable liquid dye laser systems and optical parametric oscillator (OPO) lasers, are bulky in size, not economical, and use risky flammable and toxic liquid dyes. To overcome these limitations, we are proposing a novel dual-modal photoacoustic and ultrasound imaging system based on a solid-state dye laser (SD-PAUSI), which is compact, convenient, and carries far less risk of flammability and toxicity. Using a solid-state dye handpiece that generates 650-nm wavelength, we successfully imaged the MB tube positioned deeply (~3.9 cm) in chicken breast tissue. The SLNs were also photoacoustically detected in the in vivo rats beneath a 2.2-cm-thick layer of chicken breast, which is deeper than the typical depth of SLNs in humans (1.2 ± 0.5 cm). Furthermore, we showed the multispectral capability of the PAI by switching the dye handpiece, in which the MB-dyed SLN was selectively highlighted from the surrounding vasculature. These results demonstrated the great potential of the SD-PAUSI as an easy but effective modality for SLN detection.

Reconfigurable Integrated Optofluidic Droplet Laser Arrays

Optofluidic lasers are an emerging technology for the development of miniaturized light sources and biological and chemical sensors. However, most optofluidic lasers demonstrated to date are operated at the single optical cavity level, which limits their applications in high-throughput biochemical sensing, high-speed wavelength switching, and on-chip spectroscopic analysis. Here, we demonstrated an optofluidic droplet laser array on a silicon chip with integrated microfluidics, in which four individual droplet optical cavities are generated and controlled by a 2 × 2 nozzle array. Arrays of droplets with a diameter ranging from 115 to 475 μm can be generated, removed, and regenerated on demand. The lasing threshold of the droplet laser array is in the range of 0.63-2.02 μJ/mm². An image-based lasing threshold analysis method is developed, which enables simultaneous lasing threshold measurement for all laser units within the laser array using a low-cost camera. Compared to the conventional spectrum-based threshold analysis method, the lasing threshold obtained from the image-based method showed consistent results. Our droplet laser array is a promising technology in the development of cost-effective and integrated coherent light source on a chip for point-of-care applications.

Stomach wall structure and vessels imaging by acoustic resolution photoacoustic microscopy

AIM

To image stomach wall blood vessels and tissue, layer-by-layer.

METHODS

We built up the acoustic resolution photoacoustic microscopy (AR-PAM) system for imaging layered tissues, such as the stomach wall. A tunable dye laser system was coupled to a fiber bundle. The fibers of the bundle were placed in nine directions with an incident angle of 45° around a high-frequency ultrasound transducer attached to the acoustic lens. This structure formed a dark field on the tissue surface under the acoustic lens and the nine light beams from the fibers to be combined near the focal point of the acoustic lens. The sample piece was cut from a part of the porcine stomach into a petri dish. In order to realize photoacoustic depth imaging of tumor, we designed a tumor model based on indocyanine green (ICG) dye. The ICG solution (concentration of 129 μM/mL) was mixed into molten gel, and then a gel mixture of ICG (concentration of 12.9 μM/mL) was injected into the stomach submucosa. The injection quantity was controlled by 0.1 mL to make a small tumor model.

RESULTS

An acoustic resolution photoacoustic microscopy based on fiber illumination was established and an axial resolution of 25 μm and a lateral resolution of 50 μm in its focal zone range of 500 μm has been accomplished. We tuned the laser wavelength to 600 nm. The photoacoustic probe was driven to do B-scan imaging in tissue thickness of 200 μm. The photoacoustic micro-image of mucosa and submucosa of the tissue have been obtained and compared with a pathological photograph of the tissue stained by hematoxylin-eosin staining. We have observed more detailed internal structure of the tissue. We also utilized this photoacoustic microscopy to image blood vessels inside the submucosa. High contrast imaging of the submucosa tumor model was obtained using ICG dye.

CONCLUSION

This AR-PAM is able to image layer-by-layer construction and some blood vessels under mucosa in the stomach wall without any contrast agents.

[Effect of pulsed dye laser on inhibiting early scar after maxillofacial trauma]

PURPOSE

The study was designed to explore an effective method to control early scar after maxillofacial trauma and improve the satisfaction of clinical treatment.

METHODS

Fifty skin lesions after maxillofacial trauma were divided into the experimental group and control group. Patients in the experimental group were treated with pulsed dye laser when taking out stitches, 15, 30 and 60 days later. Digital microscope photos were taken and lesion area was measured before and 3 months after laser irradiation. Adverse effects were recorded during and after each treatment as well. All patients were asked to rate their satisfaction at 3-month of follow-up. Statistical analysis was performed using SPSS 13.0 software package.

RESULTS

The efficiency of the experimental group was 74% and 37 lesions were cured or significantly improved, while the efficiency rate was 22% in the control group. Area reduction of maxillofacial lesions before and after treatment between the two groups was significantly different (P＜0.05). Patients in the experimental group were highly satisfied with the final outcomes. No severe adverse events were observed.

CONCLUSIONS

Pulsed dye laser is safe and effective in inhibiting early scar following maxillofacial trauma.

Port-Wine Stains: A Focused Review on Their Management

<p>Port-wine stain (PWS) is the second most common congenital vascular malformation characterized as ectatic capillaries and venules in the dermis that clinically appears as a deep red to purple patch on the skin. Typically, PWS progressively darken and may become hypertrophic or nodular without treatment. There are several treatment options available for PWS from topical antiangiogenic agents to laser therapies. Vascular-specific lasers are the gold standard in treating PWS and classically pulsed dye lasers are usually the treatment of choice. However, some patients with PWS are recalcitrant to PDL and may require a combination of treatment methods. Nonetheless, even with the advancements in laser therapies utilized today, it is can be difficult to achieve complete clearance of the PWS. Thus, new innovations for treating recalcitrant PWS are underway in order to improve overall patient treatment outcomes.</p> <p><em>J Drugs Dermatol. 2017;16(11):1145-1151.</em></p>.

A Retrospective Study on Efficacy of Pulsed Dye Laser and Intense Pulsed Light for the Treatment of Facial Telangiectasia

<p>Both pulsed dye laser (PDL) and intense pulsed light (IPL) systems have been demonstrated to be effective for treatment of facial telangiectasia, however there have been very few comparative studies between both treatments involving purely Asian patient populations. In this study, we performed a retrospective analysis to compare the efficacy of PDL and IPL systems for the treatment of facial telangiectasia. A total of 416 patients with facial telangiectasia who were treated by PDL or IPLs in our department from August 2012 to March 2015 were included in this study. The subjects received one of the following five treatments: PDL 595 nm (9-12 J/cm2), MaxG (500-670 nm & 870-1200 nm, 30-46 J/cm2), IPL (560-1200 nm, 18-24 J/cm2), M22 560 (560-1200 nm, 15-18 J/cm2), and M22 590 (590-1200 nm, 15-20 J/cm2). Each treatment had two sessions with 6-week intervals. The improvement percentage score in facial telangiectasia after the final treatment was evaluated by two non-treating physicians. We found almost all patients (less than 95.00%) had marked improvements or nearly complete clearance of the lesions after PDL 595 nm or MaxG treatment, as compared to 41.38%-56.58% patients in the other three groups that showed similar degrees of improvements. Both PDL 595 nm (9-12 J/cm2) and MaxG (500-670 nm & 870-1200 nm, 30-46 J/cm2) treatments resulted in significantly superior vessel clearance than the IPL systems with other wavelength bands (560-1200 nm or 590-1200 nm) and relatively lower fluence (15-24 J/cm2). Our results also suggested fluence levels account for the significant differences in the effectiveness delivered by different IPL systems. We concluded that PDL 595 nm and MaxG showed comparable clinical efficacy and both treatments resulted in most beneficial outcomes.</p> <p><em>J Drugs Dermatol. 2017;16(11):1112-1116.</em></p>.

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

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.

Label-free optical-resolution photoacoustic microscopy of superficial microvasculature using a compact visible laser diode excitation

We have developed laser-diode-based optical-resolution photoacoustic microscopy (LD-OR-PAM) of superficial microvasculature which has the desirable properties of being compact, low-cost, and label-free. A 300-mW visible pulsed laser diode was operated at a 405 ± 5 nm wavelength with a pulse energy as low as 52 nJ. By using a 3.6 MHz ultrasound transducer, the system was tested on carbon fibers with a lateral resolution of 0.95 µm and an SNR of 38 dB. The subcutaneous microvasculature on a mouse back was imaged without an exogenous contrast agent which demonstrates the potential of the proposed prototype for skin chromophores. Our eventual goal is to offer a practical and affordable multi-wavelength functional LD-OR-PAM instrument suitable for clinical applications.

Lasing in imperfectly aligned cholesterics

Optically pumped light emissions in imperfectly aligned dye-doped cholesteric cells with glance and frosted glass substrates of three different cell gap thicknesses are experimentally studied. Alignment imperfections show up in emission spectra by a broadening of the photonic bandgap (PhBG) lasing (allowed) lines at short- and long-wavelength PhBG edges and by an additional (forbidden) emission line inside the PhBG. Forbidden and allowed lines differ distinctively by their stability in the course of pumping. The origin of the forbidden line is discussed.

A linewidth-narrowed and frequency-stabilized dye laser for application in laser cooling of molecules

We demonstrate a robust and versatile solution for locking the continuous-wave dye laser for applications in laser cooling of molecules which need linewidth-narrowed and frequency-stabilized lasers. The dye laser is first stabilized with respect to a reference cavity by Pound-Drever-Hall (PDH) technique which results in a single frequency with the linewidth 200 kHz and short-term stabilization, by stabilizing the length of the reference cavity to a stabilized helium-neon laser we simultaneously transfer the ± 2 MHz absolute frequency stability of the helium-neon laser to the dye laser with long-term stabilization. This allows the dye laser to be frequency chirped with the maximum 60 GHz scan range while its frequency remains locked. It also offers the advantages of locking at arbitrary dye laser frequencies, having a larger locking capture range and frequency scanning range to be implemented via software. This laser has been developed for the purpose of laser cooling a molecular magnesium fluoride beam.

Photothermal laser speckle imaging

The analysis of speckle contrast in a time-integrated speckle pattern enables visualization of superficial blood flow in exposed vasculature, a method we call laser speckle imaging (LSI). With current methods, LSI does not enable visualization of subsurface or small vasculature, because of optical scattering by stationary structures. In this work we propose a new technique called photothermal LSI to improve the visualization of blood vessels. A 595 nm laser pulse was used to excite blood in both in vitro and in vivo samples. The high absorption coefficient of blood at this wavelength results in efficient conversion of optical energy to thermal energy, resulting in an increase in the local temperature and hence increased scatterer motion, and thus a transient decrease in speckle contrast. As a result, we found that photothermal LSI was able to visualize blood vessels that were hidden when imaged with a conventional LSI system.

Red/blue spectral shifts of laser-induced fluorescence emission due to different nanoparticle suspensions in various dye solutions

Red/blue shifts of laser-induced fluorescence (LIF) are investigated using several guest dielectric nanoscatterers, such as TiO2, ZnO, Al2O3, and SiO2, in the host Rd6G, RdB, Coumarin 4, and Coumarin 7 ethanolic solutions. A couple of inflection points are identified varying nanoparticle (NP) density into dye solutions based on LIF spectroscopy. The inflection of the spectral shift exhibits that the suspension of NPs in dye solutions significantly involves a couple of competitive chemical and optical mechanisms during photon traveling in scattering media regarding ballistic and diffusive transport. It is shown that the low, medium, and high NP additives in fluorescent suspension induce blue, red, and blue spectral shifts, respectively.

A comparison of microvascular responses to visible and near-infrared lasers

BACKGROUND AND OBJECTIVE

Pulsed dye laser (PDL) is a commonly used treatment for Port Wine Stain birthmarks (PWS). However, deeper components of PWS are often resistant to PDL. Deeper penetrating lasers, including the long pulsed Neodymium:Yttrium Aluminum Garnet (Nd:YAG) laser have been used, but carry greater risk. This study evaluates the distinct blood vessel thermal responses to visible (595 nm) and near infrared (1,064 nm) lasers using animal and numerical models.

STUDY DESIGN/MATERIALS AND METHODS

Blood vessels in the rodent dorsal skin chamber (DSC) were irradiated by a 595 nm PDL and a long-pulsed 1,064 nm Nd:YAG laser. Laser-induced immediate and 1-hour post-structural and functional changes in the vessels were documented. Numerical simulations were conducted using a 1,000 µm depth SD mouse skin fold to simulate experimental conditions.

RESULTS

PDL irradiation produced immediate blood vessel hemorrhage. Modeling indicated this occurs due to preferential heating of the superior parts of large blood vessels. Nd:YAG irradiation resulted in blood vessel constriction; modeling indicated more uniform heating of vessel walls.

CONCLUSION

PDL and Nd:YAG lasers result in distinct tissue responses. This supports different observable clinical treatment end points when using these devices. Vessel constriction associated with the Nd:YAG may be more difficult to observe and is one reason this device may carry greater risk.

Warts (non-genital)

INTRODUCTION

Warts are caused by the human papillomavirus (HPV), of which there are over 100 types. HPV probably infects the skin via areas of minimal trauma. Risk factors include use of communal showers, occupational handling of meat, and immunosuppression. In immunocompetent people, warts are harmless and resolve as a result of natural immunity within months or years.

METHODS AND OUTCOMES

We conducted a systematic review and aimed to answer the following clinical question: What are the effects of treatments for warts (non-genital)? We searched: Medline, Embase, The Cochrane Library, and other important databases up to October 2013 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS

We found 17 studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

CONCLUSIONS

In this systematic, review we present information relating to the effectiveness and safety of the following interventions: intralesional bleomycin; intralesional candida antigen; contact immunotherapy; cryotherapy; duct tape occlusion; photodynamic treatment; pulsed dye laser; surgical procedures; and topical salicylic acid.

Static and dynamic model fluorescence quenching of laser dye by carbon tetrachloride in binary mixtures

The fluorescence quenching of laser dye namely 4,4(‴)-Bis (2-butyloctyl-oxy)-p-quaterphenyl [BIBUQ] by carbon tetrachloride has been studied in different solvent mixtures of 1-4 dioxane (DN) and acetonitrile (AN) at room temperature. The quenching is found to be appreciable and a positive deviation from linearity was observed in the Stern-Volmer plot in all the solvent mixtures. Various parameters for the quenching process have been determined by sphere of action static quenching model and finite sink approximation model. The magnitudes of these rate parameters indicate that positive deviation in the Stern-Volmer (S-V) plot is both due to static and dynamic processes.

Hyperspectral all-sky imaging of auroras

A prototype auroral hyperspectral all-sky camera has been constructed and tested. It uses electro-optical tunable filters to image the night sky as a function of wavelength throughout the visible spectrum with no moving mechanical parts. The core optical system includes a new high power all-sky lens with F-number equal to f/1.1. The camera has been tested at the Kjell Henriksen Observatory (KHO) during the auroral season of 2011/2012. It detects all sub classes of aurora above ~½ of the sub visual 1kR green intensity threshold at an exposure time of only one second. Supervised classification of the hyperspectral data shows promise as a new method to process and identify auroral forms.

Correcting for spatial-resolution degradation mechanisms in OFDR via inline auxiliary points

The spatial resolution of OFDR is normally degraded by the laser phase noise, deviations from linear frequency scan and acoustic noise in the fibers. A method for mitigating these degradation mechanisms, without using an auxiliary interferometer, via inline auxiliary points, is presented and demonstrated experimentally. Auxiliary points are points that are a priori known to have (spatial) impulse reflectivities. Their responses are used for compensating the phase deviations that degrade the response of points that are further away from the source.

Tuning of split-ladder cavity by its intrinsic nano-deformation

A wide-range split-ladder photonic crystal cavity which is tuned by changing its intrinsic gap width is designed and experimentally verified. Different from the coupled cavities that feature resonance splitting into symmetric and anti-symmetric modes, the single split-ladder cavity has only the symmetric modes of fundamental resonance and second-order resonance in its band gap. Finite-difference time-domain simulations demonstrate that bipolar resonance tuning (red shift and blue shift respectively) can be achieved by shrinking and expanding the cavity's gap, and that there is a linear relationship between the resonance shifts and changes in gap width. Simulations also show that the split-ladder cavity can possess a high Q-factor when the total number of air holes in the cavity is increased. Experimentally, comb drive actuator is used to control the extent of the cavity's gap and the variation of its displacements with applied voltage is calibrated with a scanning electron microscope. The measured wavelength of the second-order resonance shifts linearly towards blue with increase in gap width. The maximum blue shift is 17 nm, corresponding to a cavity gap increase of 26 nm with no obvious degradation of Q-factor.

Wavelength-tunable picosecond soliton fiber laser with Topological Insulator: Bi2Se3 as a mode locker

Based on the open-aperture Z-scan measurement, we firstly uncovered the saturable absorption property of the topological insulator (TI): Bi2Se3. A high absolute modulation depth up to 98% and a saturation intensity of 0.49 GWcm(-2) were identified. By incorporating this novel saturable absorber material into an erbium-doped fiber laser, wavelength tunable soliton operation was experimentally demonstrated. Our result indicates that like the atomic layer graphene, the topological insulator Bi2Se3 could also operate as an effective saturable absorber for the passive mode locking of lasers at the telecommunication band.

Dye laser photodynamic therapy for Bowen's disease in a patient with epidermodysplasia verruciformis

Epidermodysplasia verruciformis (EV) is a rare heritable skin disease that results in unusual susceptibility to infection with specific types of human papillomavirus (HPV). Here we report a 53-year-old man with EV who developed Bowen's disease on his lower eyelid and the chest. Mutation analysis of EVER1 gene revealed homozygous splice acceptor site mutation (IVS8-2, A > T). In this patient, HPV3, HPV14, and HPV38 had been identified from the skin lesions. The Bowen's skin lesion on the left lower eye-lid was treated by photodynamic therapy (PDT) using 5-aminolevulinic acid (ALA) and pulsed dye laser (PDL). After two rounds of the PDT treatment, the skin lesion disappeared and a skin biopsy confirmed the efficacy of the treatment. This method was simple, less invasive than other treatments, and achieved a satisfactory cosmetic result.

The effect of reactive atypia/inflammation on the laser-induced fluorescence diagnosis of non-dysplastic Barrett's esophagus

BACKGROUND AND OBJECTIVES

Differential Normalized Fluorescence (DNF) technique has been used to distinguish high-grade dysplasia from non-dysplastic Barrett's esophagus. This technology may assist gastroenterologists in targeting biopsies, reducing the number of biopsies using the standard protocol. In the presence of reactive atypia/inflammation, it becomes difficult for the pathologist to differentiate non-dysplastic Barrett's esophagus from Barrett's esophagus with low-grade dysplasia. Before DNF technique may be used to guide target biopsies, it is critical to know whether reactive atypia/inflammation in non-dysplastic Barrett's may result in false positives. This study was conducted to determine whether DNF technique is adversely affected by the presence of reactive atypia/inflammation in non-dysplastic Barrett's esophagus resulting in false positives.

STUDY DESIGN/MATERIALS AND METHODS

Four hundred ten-nanometer laser light was used to induce autofluorescence of Barrett's mucosa in 49 patients. The clinical study included 37 males and 12 females. This was a blinded retrospective data analysis study. A total of 303 spectra were collected and matched to non-dysplastic Barrett's biopsy results. One hundred seventy-five spectra were collected from areas with a pathology of non-dysplastic Barrett's esophagus with reactive atypia/inflammation. One hundred twenty-eight spectra were collected from areas with non-dysplastic Barrett's esophagus without reactive changes/inflammation. The spectra were analyzed using the DNF Index at 480 nm and classified as positive or negative using the threshold of -0.75 × 10(-3).

RESULTS

Using DNF technique, 92.6% of non-dysplastic samples with reactive atypia/inflammation were classified correctly (162/175). 92.2% of non-dysplastic samples without reactive atypia/inflammation were classified correctly (118/128). Comparing the ratios of false positives among the two sample groups, there was not a statistically significant difference between the two groups.

CONCLUSION

Using DNF technique for classification of non-dysplastic Barrett's mucosa does not result in false-positive readings due to reactive atypia/inflammation. Target biopsies guided by DNF technique may drastically reduce the number of pinch biopsies using the standard biopsy protocol.

Optimizing the pumping configuration for the power scaling of in-band pumped erbium doped fiber amplifiers

A highly efficient (~80%), high power (18.45 W) in-band, core pumped erbium/ytterbium co-doped fiber laser is demonstrated. To the best of our knowledge, this is the highest reported efficiency from an in-band pumped 1.5 µm fiber laser operating in the tens of watts regime. Using a fitted simulation model, we show that the significantly sub-quantum limit conversion efficiency of in-band pumped erbium doped fiber amplifiers observed experimentally can be explained by concentration quenching. We then numerically study and experimentally validate the optimum pumping configuration for power scaling of in-band, cladding pumped erbium doped fiber amplifiers. Our simulation results indicate that a ~77% power conversion efficiency with high output power should be possible through cladding pumping of current commercially available pure Erbium doped active fibers providing the loss experienced by the cladding guided 1535 nm pump due to the coating absorption can be reduced to an acceptable level by better coating material choice. The power conversion efficiency has the potential to exceed 90% if concentration quenching of erbium ions can be reduced via improvements in fiber design and fabrication.

TRASER--Total Reflection Amplification of Spontaneous Emission of Radiation

Background and Objective

Light and lasers in medical therapy have made dramatic strides since their invention five decades ago. However, the manufacture of lasers can be complex and expensive which often makes treatments limited and costly. Further, no single laser will provide the correct parameters to treat all things. Hence, laser specialists often need multiple devices to practice their specialty. A new concept is described herein that has the potential to replace many lasers and light sources with a single ‘tunable’ device.

Study Design/Material and Methods

This device amplifies spontaneous emission of radiation by capturing and retaining photons through total internal reflection, hence the acronym Total Reflection Amplification of Spontaneous Emission of Radiation, or TRASER.

Results

Specific peaks of light can be produced in a reproducible manner with high peak powers of variable pulse durations, a large spot size, and high repetition rate.

Conclusion

Considering the characteristics and parameters of Traser technology, it is possible that this one device would likely be able to replace the pulsed dye laser and many other light based systems.

Immunohistochemistry of angiogenesis mediators before and after pulsed dye laser treatment of angiomas

BACKGROUND AND OBJECTIVE

Tissue effects of vascular lesion laser treatment are incompletely understood. Injury caused by pulsed dye laser (PDL) treatment may result in altered expression of mediators associated with angiogenesis.

MATERIALS AND METHODS

Eight human subjects had one angioma treated with PDL (7 mm, 1.5 millisecond pulse duration, 9 J/cm(2), cryogen spray cooling of 30 millisecond with a 30 millisecond delay). One week later, three biopsies were taken: normal skin, untreated angioma, angioma post-PDL. Tissue was frozen and sections processed for immunohistochemistry staining of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), matrix metalloproteinase 9 (MMP-9), and angiopoietin 2 (ANG-2). Images were graded in a blinded fashion by a board certified dermatopathologist.

RESULTS

There were no clear trends in VEGF expression in the epidermis, dermis, or endothelial cells. As compared to normal skin, angiomas demonstrated the following: bFGF was decreased in the epidermis; MMP-9 was decreased or unchanged in the epidermis and increased in the endothelial cells; ANG-2 was increased in the endothelial cells. When comparing normal skin to angiomas + PDL, bFGF was decreased in the epidermis and increased in the dermis; MMP-9 was decreased or unchanged in the epidermis; ANG-2 was again increased in the endothelial cells. Comparison of staining in angioma to angioma + PDL samples revealed increased dermal bFGF expression.

CONCLUSION

Alterations in angiogenesis mediators were noted after PDL. Angiogenesis mediator changes associated with PDL treatment differed from those previously reported for incisional biopsies. This pilot study can guide future work on laser-induced alterations in vascular lesions and such information may ultimately be used to optimize treatment outcomes.

Near-infrared tunable lasers with polymer waveguide Bragg gratings

Wavelength tunable lasers operating at near infrared (NIR) wavelength are demonstrated through the thermo-optic (TO) refractive index tuning of polymer waveguide Bragg reflectors. The polymer-waveguide device has superior TO efficiency for substantially changing the refractive index, and it enables direct tuning of the Bragg reflection wavelength over a wide range. The waveguide is optimized for NIR wavelengths, and a third-order Bragg reflector is incorporated for facilitating fabrication of the grating. The laser exhibits an output power of 0 dBm, a side-mode suppression ratio of 40 dB, and a tuning range of 21 nm.

High power ultra-widely tuneable femtosecond pulses from a non-collinear optical parametric oscillator (NOPO)

We present an ultra-widely tunable non-collinear optical parametric oscillator with an average output power of more than 3 W and a repetition frequency of 34 MHz. The system is pumped by the second harmonic of a femtosecond Yb:KLu(WO4)2 thin-disk laser oscillator. The wavelength of the signal pulse can be rapidly tuned over a wide range from the visible to the NIR just by scanning the resonator length.

A switchable digital microfluidic droplet dye-laser

Digital microfluidic devices allow the manipulation of droplets between two parallel electrodes. These electrodes can act as mirrors generating a micro-cavity, which can be exploited for a droplet dye-laser. Three representative laser-dyes with emission wavelengths spanning the whole visible spectrum are chosen to show the applicability of this concept. Sub-microlitre droplets of laser-dye solution are moved in and out of a lasing site on-chip to down-convert the UV-excitation light into blue, green and red laser-pulses.

Glomuvenous Malformations (Familial generalized multiple glomangiomas)

A 15-year-old boy with a diagnosis of generalized multiple glomangiomas was referred for evaluation and treatment of enlarging and increasingly painful lesions on his right ankle. The patient underwent a series of two treatments with long-pulsed KTP 1064 nm laser that resulted in substantial improvement in appearance and decreased pain. Generalized glomuvenous malformations, or multiple glomangiomas, are the less common presentation of proliferation of glomus cells and may have extracutaneous involvement. Whereas surgical management is often employed and definitive for solitary lesions, interventions such as laser therapy, may be beneficial for improvement of functional impairment and cosmesis as was observed in our patient.

A tunable 3D optofluidic waveguide dye laser via two centrifugal Dean flow streams

This paper presents a tunable optofluidic waveguide dye laser utilizing two centrifugal Dean flows. The centrifugal Dean flow increases the light confinement of the dye laser by shaping a three-dimensional (3D) liquid waveguide from curved microchannels. The active medium with the laser dye is dissolved in the liquid core and pumped with an external pump laser to produce stimulated emission. The laser's Fabry-Pérot microcavity is formed with a pair of aligned gold-coated fiber facets to amplify the fluorescent emission. The advantage of the 3D optofluidic waveguide dye laser is its higher efficiency, thus to obtain lasing at a reduced threshold (60%) with higher output energy. The demonstrated slope efficiency is at least 3-fold higher than its traditional two-dimensional equivalent. In addition, the laser output energy can be varied on demand by tuning the flow rates of the two flows. This technique provides a versatile platform for high potential applications microfluidic biosensor and bioanalysis.

Spectroscopic analysis and efficient diode-pumped 1.9 μm Tm3+-doped β'-Gd2(MoO4)3 crystal laser

Tm3+-doped β'-Gd2(MoO4)3 single crystal was grown by the Czochralski method. Spectroscopic analysis was carried out along different polarizations. End-pumped by a quasi-cw diode laser at 795 nm in a plano-concave cavity, an average laser output power of 58 mW around 1.9 μm was achieved in a 0.93-mm-thick crystal when the output coupler transmission was 7.1%. The absorbed pump threshold was 8 mW and the slope efficiency of the laser was 57%. This crystal has smooth and broad gain curve around 1.9 μm, which shows that it is also a potential gain medium for tunable and short pulse lasers.

Tunable negative-tap photonic microwave filter based on a cladding-mode coupler and an optically injected laser of large detuning

A tunable negative-tap photonic microwave filter using a cladding-mode coupler together with optical injection locking of large wavelength detuning is demonstrated. Continuous and precise tunability of the filter is realized by physically sliding a pair of bare fibers inside the cladding-mode coupler. Signal inversion for the negative tap is achieved by optical injection locking of a single-mode semiconductor laser. To couple light into and out of the cladding-mode coupler, a pair of matching long-period fiber gratings is employed. The large bandwidth of the gratings requires injection locking of an exceptionally large wavelength detuning that has never been demonstrated before. Experimentally, injection locking with wavelength detuning as large as 27 nm was achieved, which corresponded to locking the 36-th side mode. Microwave filtering with a free-spectral range tunable from 88.6 MHz to 1.57 GHz and a notch depth larger than 35 dB was obtained.

Second harmonic generation in AlGaAs photonic wires using low power continuous wave light

We report modal phase matched (MPM) second harmonic generation (SHG) in high-index contrast AlGaAs sub-micron ridge waveguides, by way of sub-mW continuous wave powers at telecommunication wavelengths. We achieve an experimental normalized conversion efficiency of ~14%/W/cm2, obtained through a careful sub-wavelength design supporting both the phase matching requirement and a significant overlap efficiency. Furthermore, the weak anomalous dispersion, robust fabrication technology and possible geometrical and thermal tuning of the device functionality enable a fully integrated multi-functional chip for several critical areas in telecommunications, including wavelength (time) division multiplexing and quantum entanglement.

True-time delay line with separate carrier tuning using dual-parallel MZM and stimulated Brillouin scattering-induced slow light

We experimentally demonstrate a novel tunable true-time delay line with separate carrier tuning using dual-parallel Mach-Zehnder modulator and stimulated Brillouin scattering-induced slow light. The phase of the optical carrier can be continuously and precisely controlled by simply adjusting the dc bias of the dual-parallel Mach-Zehnder modulator. In addition, both the slow light and single-sideband modulation can be simultaneously achieved in the stimulated Brillouin scattering process with three types of configuration. Finally, the true-time delay technique is clearly verified by a two-tap incoherent microwave photonic filter as the free spectral range of the filter is changed.

[Review of clinical features of circumscribed choroidal hemangioma in 28 cases]

PURPOSE

To review the clinical features and management of circumscribed choroidal hemangioma.

METHODS

Twenty eight cases of circumscribed choroidal hemangioma diagnosed at Tokyo Medical University Hospital from 1991 through 2008 were reviewed. We retrospectively studied the frequency of the individual tumors, gender, age, size of tumors, presence of serous detachment and hyperopia, management and outcome.

RESULTS

Sixteen patients were men and 12 cases were women. The average age was 55 years. The average basal diameter of the tumors was 3.3 optic disc. Serous retinal detachment was observed in 19 cases (70%). Seventeen eyes agreed with the definition of hyperopia, 10 cases (59%) developed hyperopia. Thirteen cases (46%) were observed without any treatment, 10 cases(36%) were treated with transpupillary thermotherapy (TTT) and 5 cases (18%) were treated with dye laser. Thirteen cases (46%) showed improvement, 13 cases (46%) remained constant and 2 cases (7%) showed deterioration.

CONCLUSION

Circumscribed choroidal hemangioma is a relatively rare clinical entity. The management should be tailored to the individual patients including the tumor size presence of serous detachement and visual acuity.

Stable, 12 W, continuous-wave single-frequency Nd:YVO4 green laser polarized and dual-end pumped at 880 nm

Based on a polarized and dual-end pumping scheme and a ring resonator, a stable, high power and high beam quality continuous-wave single-frequency Nd:YVO4 green laser directly pumped at 880 nm has been fabricated. A measured maximum output power of 12 W at 532 nm was obtained with a conversion efficiency of 23.1%. The stability of the output was better than ±0.5% and no mode hopping was observed over a period of five hours. The output beam was almost diffraction limited with a measured beam quality of M2(x)=1.03 and M2(y)=1.02. The intensity noise reached the shot noise limit (SNL) for analysis frequencies above 3.5 MHz, and the phase noise was 1.3 dB above the SNL in the range of 2 to 20 MHz.

Pulse width tunable passively mode-locked Nd:YVO4 laser based on hybrid laser gain medium locations

A pulse width tunable passively mode-locked laser with a wavelength of 1,064 nm and two Nd:YVO(4) crystals located in asymmetric positions is demonstrated. By adjusting the pump power of the crystals, the pulse width can be continuously tuned from 8.8 to 20.3 ps at a stable mode-locked repetition rate of 122 MHz. A theoretical model is proposed to describe the experiment results phenomenologically. In this system, a maximum output power of 4.44 W is achieved with a pump of 13.68 W, corresponding to an optical-to-optical efficiency of 32.5%. The beam quality factor, M(2), is found to be M(2)(x) = 1.15 and M(2)(y) = 1.13 in the orthogonal directions at an output power of 3.2 W.

Optical characterization of coupled resonator slow-light rib waveguides

We report on the design, fabrication and optical characterization of a slow light waveguide created using a linear array of coupled resonators in a large cross-section rib waveguide. Structures with as many as 25 high aspect ratio resonators are experimentally investigated. The measured propagation loss, group velocity, and delay-bandwidth product (DBP) are presented. The metric DBP/unit loss is also introduced, with a value 38/dB. Finally we discuss a method for further reducing loss in the slow-light rib waveguide.

40-80-160 GHz tunable mode-locked semiconductor fiber laser incorporating a nonlinear optical loop mirror

We demonstrate a tunable mode-locked semiconductor fiber laser incorporating a nonlinear optical loop mirror and synchronized to an external optical signal at 40 GHz, 80 GHz, and 160 GHz. The laser generates sech(2) pulses as short as 2.0 ps, 1.7 ps, and 1.3 ps at 40 GHz, 80 GHz, and 160 GHz, respectively, and is tunable within the C-band. The maximum root-mean-square timing jitter of the laser is 580 fs at 40 GHz and 80 GHz.

Tunable directly modulated fiber ring laser using a reflective semiconductor optical amplifier for WDM access networks

We have proposed a stable, wideband, and tunable directly modulated fiber ring laser (TDMFRL) by using a reflective semiconductor optical amplifier (RSOA) and an optical tunable filter (OTF). For use in a bidirectional access network, the TDMFRL not only generates downstream data traffic but also serves as the wavelength-selecting injection light source for the Fabry-Pérot laser diode (FP-LD) located at the subscriber site. We experimentally demonstrated a bidirectional transmission at 1.25-Gb/s direct modulation over a 25-km single-mode fiber (SMF), thereby showing good performance in a wavelength division multiplexing (WDM) access network.

High efficiency cholesteric liquid crystal lasers with an external stable resonator

An amplified cholesteric liquid crystal (CLC) laser performance is demonstrated by utilizing a binary-dye mixture (with 62 wt% DCM and 38 wt% PM597) as the active medium and an external stable resonator. The measured results show that the laser efficiency is enhanced as compared to the highest efficiency of each individual dye. Furthermore, using such an active CLC in an external stable resonator leads to a approximately 92X improved efficiency over the single CLC laser. In this instance, the binary-dye doped CLC simultaneously functions as laser oscillator and amplifier.

Granuloma faciale with disseminated extra facial lesions

Granuloma faciale (GF) is a rare cutaneous disorder categorized as a localized form of small vessel vasculitis. Clinically, it manifests as single or multiple, well-demarcated, red-brown plaques, papules and nodules, nearly always confined to the face. Herein, we report a 39-year-old man with multiple red-brown, infiltrated plaques on his face and extrafacial lesions on the back, shoulders, and both arms. Skin biopsy revealed typical histopathological findings of GF. The patient failed to respond to pulsed dye laser, but intralesional triamcinolone combined with cryotherapy led to an acceptable response.