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A full free spectral range tuning of p-i-n doped Gallium Nitride microdisk cavity  [PDF]
Nan Niu,Tsung-Li Liu,Igor Aharonovich,Kasey J. Russell,Alexander Woolf,Thomas C. Sadler,Haitham A. R. El-Ella,Menno J. Kappers,Rachel A. Oliver,Evelyn L. Hu
Physics , 2012, DOI: 10.1063/1.4744947
Abstract: Effective, permanent tuning of the whispering gallery modes (WGMs) of p-i-n doped GaN microdisk cavity with embedded InGaN quantum dots over one free spectral range is successfully demonstrated by irradiating the microdisks with a ultraviolet laser (380nm) in DI water. For incident laser powers between 150 and 960 nW, the tuning rate varies linearly. Etching of the top surface of the cavity is proposed as the driving force for the observed shift in WGMs, and is supported by experiments. The tuning for GaN/InGaN microdisk cavities is an important step for deterministically realizing novel nanophotonic devices for studying cavity quantum electrodynamics.
Radiative transfer model STORM for full Stokes vector calculations in the visible and near infrared spectral range  [PDF]
U. B?ttger,R. Preusker
Advances in Radio Science : Kleinheubacher Berichte , 2006,
Abstract: Based on the Matrix-Operator Method the radiative transfer code STORM (STOkes vector Radiative transfer Model) is introduced, which was developed in a joint project of DLR and Institut f{ü}r Weltraumwissenschaften-Freie Universit t Berlin. STORM calculates the Stokes parameters (I, Q, U, V) in a plane parallel, multi layered atmosphere in the visible and near infrared spectral range. The scattering characteristics of aerosols are determined by Mie theory. The surface represents a Lambertian reflector or a wind ruffled water surface described by Cox-Munk model. The results of one calculation are the upward and downward directed Stokes parameters for one wavelength at a desired number of sun incident and viewing angles at varying altitudes in the principal plane and other azimuth angles. STORM is applied for an analysis in view of designing downward looking Earth observing optical remote sensing systems and values of the degree of polarization are presented as generic basis for remote sensing system design and data processing.
Electromagnetic cloaking in the visible frequency range  [PDF]
I. I. Smolyaninov,Y. J. Hung,C. C. Davis
Physics , 2007, DOI: 10.1364/OL.33.001342
Abstract: Electromagnetic metamaterials provide unprecedented freedom and flexibility to introduce new devices, which control electromagnetic wave propagation in very unusual ways. Very recently theoretical design of an "invisibility cloak" has been suggested, which has been realized at microwave frequencies in a two-dimensional cylindrical geometry. In this communication we report on the experimental realization of the dielectric permittivity distribution required for non-magnetic cloaking in the visible frequency range.
High-Power ZBLAN Glass Fiber Lasers: Review and Prospect  [PDF]
Xiushan Zhu,N. Peyghambarian
Advances in OptoElectronics , 2010, DOI: 10.1155/2010/501956
Abstract: ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF), considered as the most stable heavy metal fluoride glass and the excellent host for rare-earth ions, has been extensively used for efficient and compact ultraviolet, visible, and infrared fiber lasers due to its low intrinsic loss, wide transparency window, and small phonon energy. In this paper, the historical progress and the properties of fluoride glasses and the fabrication of ZBLAN fibers are briefly described. Advances of infrared, upconversion, and supercontinuum ZBLAN fiber lasers are addressed in detail. Finally, constraints on the power scaling of ZBLAN fiber lasers are analyzed and discussed. ZBLAN fiber lasers are showing promise of generating high-power emissions covering from ultraviolet to mid-infrared considering the recent advances in newly designed optical fibers, beam-shaped high-power pump diodes, beam combining techniques, and heat-dissipating technology. 1. Introduction Since the first demonstration of laser emission from a ruby crystal (chromium-doped corundum) in 1960 [1], hundreds of crystals and glasses doped with rare-earth ions have been fabricated and utilized in solid-state lasers to generate coherent emissions at different wavelengths. In contrast to crystals, glasses do not only have broad laser transitions which are essential conditions for wavelength tuning and ultrashort pulses generation but also have broad absorption spectra that relieve the wavelength tolerance for the pump sources. Most importantly, single-mode optical fibers, as the most flexible and compact gain media for high-efficiency and excellent beam-quality laser generation, are mostly drawn from glasses. Although crystalline fibers can be drawn using techniques of edge-defined film-fed growth [2], micropulling-down [3], and laser heated pedestal growth [4], their cores cannot be precisely controlled to be small enough to ensure exclusive single-transverse-mode guiding and their lengths are also technically limited. To date, silicate, phosphate, fluoride, and chalcogenide glasses can be drawn into single-mode fibers. A variety of lasers have also been demonstrated in these glass fibers. The spectral range of glass fiber lasers can cover from ultraviolet (UV) to mid-infrared and the output power of a single-element fiber laser can be up to 6 kilo-watts [5]. In contrast to other lasers, the attractive features of fiber lasers include outstanding heat-dissipating capability, excellent beam quality, high optical conversion efficiency, simplicity and compactness, high single-pass gain, low laser threshold, and broad gain
Determination of luminous color gamut of continuous emissions in visible waveband
Anquan Wang,Xiaofang Cheng,Tairan Fu,Shaosong Lu
Chinese Science Bulletin , 2002, DOI: 10.1007/BF03184107
Abstract: Regarding objects of monotonic emissivities in the visible waveband, the concept of color-kernel body is put forward. With this concept, the luminous color of actual objects is found out to be the mixture of the radiative colors of a blackbody and a color-kernel body with different weights. The locus of the isothermal radiative colors is a straight-line segment in the chromaticity diagram. The whole color gamut of continuous emissions is about 17% of the entire gamut of natural colors and at its bottom.
A New and Inexpensive Pyranometer for the Visible Spectral Range  [PDF]
Miguel A. Martínez,José M. Andújar,Juan M. Enrique
Sensors , 2009, DOI: 10.3390/s90604615
Abstract: This paper presents the design, construction and testing of a new photodiode-based pyranometer for the visible spectral range (approx. 400 to 750 nm), whose principal characteristics are: accuracy, ease of connection, immunity to noise, remote programming and operation, interior temperature regulation, cosine error minimisation and all this at a very low cost, tens of times lower than that of commercial thermopile-based devices. This new photodiode-based pyranometer overcomes traditional problems in this type of device and offers similar characteristics to those of thermopile-based pyranometers and, therefore, can be used in any installation where reliable measurement of solar irradiance is necessary, especially in those where cost is a deciding factor in the choice of a meter. This new pyranometer has been registered in the Spanish Patent and Trademark Office under the number P200703162.
Tuning Range Image Segmentation by Genetic Algorithm  [cached]
Pignalberi Gianluca,Cucchiara Rita,Cinque Luigi,Levialdi Stefano
EURASIP Journal on Advances in Signal Processing , 2003,
Abstract: Several range image segmentation algorithms have been proposed, each one to be tuned by a number of parameters in order to provide accurate results on a given class of images. Segmentation parameters are generally affected by the type of surfaces (e.g., planar versus curved) and the nature of the acquisition system (e.g., laser range finders or structured light scanners). It is impossible to answer the question, which is the best set of parameters given a range image within a class and a range segmentation algorithm? Systems proposing such a parameter optimization are often based either on careful selection or on solution space-partitioning methods. Their main drawback is that they have to limit their search to a subset of the solution space to provide an answer in acceptable time. In order to provide a different automated method to search a larger solution space, and possibly to answer more effectively the above question, we propose a tuning system based on genetic algorithms. A complete set of tests was performed over a range of different images and with different segmentation algorithms. Our system provided a particularly high degree of effectiveness in terms of segmentation quality and search time.
Design and properties of hollow antiresonant fibers for the visible and near infrared spectral range  [PDF]
Walter Belardi
Physics , 2015, DOI: 10.1109/JLT.2015.2477775
Abstract: Hollow core antiresonant fibers offer new possibilities in the near infrared and visible spectral range. I show here that the great flexibility of this technology can allow the design and fabrication of hollow core optical fibers with an extended transmission bandwidth in the near infrared and with very low optical attenuation in the visible wavelength regime. A very low attenuation of 175dB/km at 480nm is reported. A modification of the design of the studied fibers is proposed in order to achieve fast-responding gas detection.
Directional character of soil surface reflectance in the visible and near-infrared range
J. Cierniewski,M. Verbrugghe,S. Bia?…??ousz,J. Chmiel
International Agrophysics , 1995,
Abstract: The paper shows the importance of directional effects on soil reflectance in the visible and near -infrared range. It includes physical principles of surface interactions with radiation in this spectral range, and examples of soil reflectance measurements performed during Polish-French cooperation.
Diamagnetic nature of stratified thin metals in visible range  [PDF]
Masanobu Iwanaga
Physics , 2007,
Abstract: It is numerically demonstrated that effectively strong diamagnetic resonance emerges at visible frequencies in stratified metal-dielectric metamaterials. The effective optical constants are extracted by two-complex reflectivity method. It is clarified that the effective diamagnetic response originates from local diamagnetism at stratified thin metals. The effective diamagnetism is crucially sensitive to the sturucture of unitcell. The effective diamagnetic response is always associated with effective plasma frequency and is therefore regarded as a magnetic component of the collective excitation.
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