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Multiple diode laser

Y Chen, Kevin K Lehmann, Y Peng, L M Pratt, J R White, S B Cadieux, B Sherwood Lollar, G Lacrampe-Couloume, T C Onstott
In this study, near-infrared continuous wave cavity ring-down spectroscopy was applied to the measurement of the δ(2)H of methane (CH4). The cavity ring-down spectrometer (CRDS) system consisted of multiple DFB laser diodes to optimize selection of spectral line pairs. By rapidly switching measurements between spectral line peaks and the baseline regions, the long-term instrumental drift was minimized, substantially increasing measurement precision. The CRDS system coupled with a cryogenic pre-concentrator measured the δ(2)H of terrestrial atmospheric CH4 from 3 standard liters of air with a precision of ±1...
October 2016: Astrobiology
David M Harris, Lou Reinisch
BACKGROUND AND OBJECTIVE: Selective killing of pathogens by laser is possible due to the difference in absorption of photon energy by pathogens and host tissues. The optical properties of pathogenic microorganisms are used along with the known optical properties of soft tissues in calculations of the laser-induced thermal response of pathogen colonies embedded in a tissue model. The objective is to define the laser parameters that optimize pathogen destruction and depth of the bactericidal effect...
October 10, 2016: Lasers in Surgery and Medicine
Jeffrey M Pietryga, Young-Shin Park, Jaehoon Lim, Andrew F Fidler, Wan Ki Bae, Sergio Brovelli, Victor I Klimov
The field of nanocrystal quantum dots (QDs) is already more than 30 years old, and yet continuing interest in these structures is driven by both the fascinating physics emerging from strong quantum confinement of electronic excitations, as well as a large number of prospective applications that could benefit from the tunable properties and amenability toward solution-based processing of these materials. The focus of this review is on recent advances in nanocrystal research related to applications of QD materials in lasing, light-emitting diodes (LEDs), and solar energy conversion...
September 28, 2016: Chemical Reviews
Dae-Suk Kim, Caleb Holloway, Bongtae Han, Avram Bar-Cohen
A hybrid experimental/numerical method is proposed for predicting the junction temperature distribution in a high-power laser diode (LD) bar with multiple emitters. A commercial water-cooled LD bar with multiple emitters is used to illustrate and validate the proposed method. A unique experimental setup is developed and implemented first to measure the average junction temperatures of the LD bar emitters. After measuring the heat dissipation of the LD bar, the effective heat transfer coefficient of the cooling system is determined inversely from the numerical simulation using the measured average junction temperature and the heat dissipation...
September 20, 2016: Applied Optics
Mini Saluja, Harpreet Singh Grover, Pankaj Choudhary
INTRODUCTION: Dentinal hypersensitivity is one of the most common problem, encountered in dental practice but has least predictable treatment outcome. The advent of lasers in dentistry has provided an additional therapeutic option for treating dentinal hypersensitivity. Although various lasers have been tried over a period of time to treat dentinal hypersensitivity, but still the doubt persist as to which laser leads to maximum dentinal tubular occlusion and is most suitable with minimal hazardous effects...
July 2016: Journal of Clinical and Diagnostic Research: JCDR
Yongxiong Ren, Long Li, Zhe Wang, Seyedeh Mahsa Kamali, Ehsan Arbabi, Amir Arbabi, Zhe Zhao, Guodong Xie, Yinwen Cao, Nisar Ahmed, Yan Yan, Cong Liu, Asher J Willner, Solyman Ashrafi, Moshe Tur, Andrei Faraon, Alan E Willner
To increase system capacity of underwater optical communications, we employ the spatial domain to simultaneously transmit multiple orthogonal spatial beams, each carrying an independent data channel. In this paper, we show up to a 40-Gbit/s link by multiplexing and transmitting four green orbital angular momentum (OAM) beams through a single aperture. Moreover, we investigate the degrading effects of scattering/turbidity, water current, and thermal gradient-induced turbulence, and we find that thermal gradients cause the most distortions and turbidity causes the most loss...
2016: Scientific Reports
Sunil Manjila, Margherita Mencattelli, Benoit Rosa, Karl Price, Georgios Fagogenis, Pierre E Dupont
OBJECTIVE Rigid endoscopes enable minimally invasive access to the ventricular system; however, the operative field is limited to the instrument tip, necessitating rotation of the entire instrument and causing consequent tissue compression while reaching around corners. Although flexible endoscopes offer tip steerability to address this limitation, they are more difficult to control and provide fewer and smaller working channels. A middle ground between these instruments-a rigid endoscope that possesses multiple instrument ports (for example, one at the tip and one on the side)-is proposed in this article, and a prototype device is evaluated in the context of a third ventricular colloid cyst resection combined with septostomy...
September 2016: Neurosurgical Focus
Pu Li, Xiaogang Yi, Xianglian Liu, Dongliang Zhao, Yongpeng Zhao, Yuncai Wang
An analog comparator is one of the core units in all-optical analog-to-digital conversion (AO-ADC) systems, which digitizes different amplitude levels into two levels of logical '1' or '0' by comparing with a defined decision threshold. Although various outstanding photonic ADC approaches have been reported, almost all of them necessitate an electrical comparator to carry out this binarization. The use of an electrical comparator is in contradiction to the aim of developing all-optical devices. In this work, we propose a new concept of an all-optical analog comparator and numerically demonstrate an implementation based on a quarter-wavelength-shifted distributed feedback laser diode (QWS DFB-LD) with multiple quantum well (MQW) structures...
2016: Scientific Reports
Hyoseung Shin, Ji-Seon Yoon, Wooseok Koh, Jin Yong Kim, Chang-Hyun Kim, Kang Min Han, Eo Jin Kim, Ohsang Kwon
BACKGROUND AND OBJECTIVE: Lasers have been successfully used for decades to remove dark hair. However, laser removal of nonpigmented hair is challenging due to the lack of chromophores. The aim of this study was to use photodynamic therapy (PDT) to remove nonpigmented hair. STUDY DESIGN/MATERIAL AND METHODS: We compared the efficacy of permanent hair reduction in white BALB/c and black C57BL/6 mice treated with PDT or an 800-nm diode laser. We collected skin biopsy specimens and investigated post-PDT histologic changes and molecular changes...
October 2016: Lasers in Surgery and Medicine
Hannah John, Nikolaos Manoloudakis, J Stephen Sinclair
AIM: To conduct a systematic review of the effectiveness of various types of lasers (and light based therapies) for the treatment of hidradenitis suppurativa (HS) and to establish recommendations based on our findings. DATA SOURCES: MEDLINE, Cochrane and PubMed databases. STUDY SELECTION: English language studies describing the use of laser for the treatment of HS. DATA EXTRACTION: Multiple reviewers performed independent extraction and identified 22 studies that met the inclusion and exclusion criteria...
October 2016: Journal of Plastic, Reconstructive & Aesthetic Surgery: JPRAS
M Roncati, D Lauritano, F Cura, F Carinci
Since the laser and photomodulation were discovered over 50 years, they have been used for many applications in medicine and in dentistry also. In particular, light-emitting diodes therapy (LT) achieved a great success in medical treatment and photo-therapy. In the decades, LT has been used for several therapeutic purposes. Many beneficial effects have been demonstrated in vitro and in vivo, including antibacterial, antiviral, antitumor, cell differentiation, immune potentiating and tissue repair activities...
April 2016: Journal of Biological Regulators and Homeostatic Agents
Michelle L Zoccolillo, Stephen C Rogers, Thomas S Mang
BACKGROUND: Antimicrobial Photodynamic therapy (aPDT) has demonstrated efficacy in situations where conventional antibiotic therapies can be challenged such as biofilms, gram-negative bacteria, and antimicrobial resistant organisms. Surface characteristics can affect biofilm adherence and integrity and so may modify the effectiveness of aPDT. This study investigates the killing efficacy of aPDT on S. mutans biofilms grown on relevant dental substrata, examining the killing efficacy and specifically the effects of aPDT on the biofilm matrix architecture...
June 1, 2016: Lasers in Surgery and Medicine
Changlei Guo, Kaijun Che, Huiying Xu, Pan Zhang, Deyu Tang, Changyan Ren, Zhengqian Luo, Zhiping Cai
We propose and experimentally demonstrate a simple scheme for generating optical frequency combs (OFCs) in a fiber-ring/microresonator laser system. The ultrahigh Q whispering gallery mode microresonator is employed both as a mode reflection mirror to generate erbium lasing and as a Kerr-nonlinearity initiator that introduces optical parametric oscillation signals to form OFCs. By controlling the coupling position between the fiber taper and microresonator, optimizing the fiber polarization, as well as the pump power from a 974 nm laser diode (LD), versatile OFCs can be tuned out from single-wavelength states...
June 1, 2016: Optics Letters
Haiyang Zhang, Marc Brunel, Marco Romanelli, Marc Vallet
This paper investigates the radio frequency (RF) up-conversion properties of a frequency-shifting external cavity on a laser beam. We consider an infrared passively Q-switched pulsed laser whose intensity modulation results from the multiple round-trips in the external cavity, which contains a frequency shifter. The output beam undergoes optical second-harmonic generation necessary to reach the green wavelength. We model the pulse train using a rate-equation model to simulate the laser pulses, together with a time-delayed interference calculation taking both the diffraction efficiency and the Gaussian beam propagation into account...
April 1, 2016: Applied Optics
Hua Yang, Mingqi Yang, Padraic E Morrissey, Dan Lu, Bi Wei Pan, Lingjuan Zhao, Brian Corbett, Frank H Peters
A 1x2 multi-mode-interferometer (MMI) laser diode was successfully designed and fabricated, which demonstrated three coherent outputs of tunable single frequency emission with more than 30dB side mode suppression ratio (SMSR), a tuning range of 25nm in C and L band, as well as 750 kHz linewidth. This 1x2 MMI laser could be expanded to more advanced configurations such as 1xN or MxN (M≥1, N>2) MMI lasers to achieve a multiple coherent output source. In addition, these lasers do not require material regrowth and high resolution gratings which can significantly increase the yield and reduce the cost...
March 21, 2016: Optics Express
Rajeh Mundle, Christian Carvajal, Aswini K Pradhan
ZnO has intrinsic semiconductor conductivity because of an unintentional doping mechanism resulting from the growth process that is mainly attributable to oxygen vacancies (VO) positioned in the bandgap. ZnO has multiple electronic states that depend on the number of vacancies and the charge state of each vacancy. In addition to the individual electron states, the vacancies have different vibrational states. We developed a high-temperature precursor vapor mask technique using Al2O3 to pattern the atomic layer deposition of ZnO and Al:ZnO layers on ZnO-based substrates...
May 17, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Jintao Liang, Mingyuan Guan, Guoyin Huang, Hengming Qiu, Zhengcheng Chen, Guiyin Li, Yong Huang
A biomarker is related to the biological status of a living organism and shows great promise for the early prediction of a related disease. Herein we presented a novel structured light-addressable potentiometric sensor (LAPS) for the determination of a model biomarker, human immunoglobulin G (hIgG). In this system, the goat anti-human immunoglobulin G antibody was used as recognition element and covalently immobilized on the surface of light-addressable potentiometric sensor chip to capture human immunoglobulin G...
June 2016: Materials Science & Engineering. C, Materials for Biological Applications
Chengzhi Shi, Marc Dubois, Yun Chen, Lei Cheng, Hamidreza Ramezani, Yuan Wang, Xiang Zhang
Parity-time (PT) symmetric systems experience phase transition between PT exact and broken phases at exceptional point. These PT phase transitions contribute significantly to the design of single mode lasers, coherent perfect absorbers, isolators, and diodes. However, such exceptional points are extremely difficult to access in practice because of the dispersive behaviour of most loss and gain materials required in PT symmetric systems. Here we introduce a method to systematically tame these exceptional points and control PT phases...
2016: Nature Communications
Fabrizio Castellano, Lianhe Li, Edmund H Linfield, A Giles Davies, Miriam S Vitiello
Mode-locked comb sources operating at optical frequencies underpin applications ranging from spectroscopy and ultrafast physics, through to absolute frequency measurements and atomic clocks. Extending their operation into the terahertz frequency range would greatly benefit from the availability of compact semiconductor-based sources. However, the development of any compact mode-locked THz laser, which itself is inherently a frequency comb, has yet to be achieved without the use of an external stimulus. High-power, electrically pumped quantum cascade lasers (QCLs) have recently emerged as a promising solution, owing to their octave spanning bandwidths, the ability to achieve group-velocity dispersion compensation and the possibility of obtaining active mode-locking...
2016: Scientific Reports
Hilary S Brader, Lucy H Y Young
The subthreshold diode micropulse laser is a form of non-damaging thermal laser therapy which has shown efficacy in multiple retinal conditions. The purpose of this article is to review the use of subthreshold diode micropulse laser as an emerging treatment modality for the treatment of retinal disease. The proposed mechanisms of action, safety, efficacy, recommended laser treatment parameters, and clinical applications for which the use of subthreshold diode micropulse laser has been studied will be reviewed...
2016: Seminars in Ophthalmology
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