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Optical Amplifier
An optical amplifier is a device that amplifies an optical signal directly, without the need to first convert it to an electrical signal. An optical amplifier may be thought of as a laser without an optical cavity, or one in which feedback from the cavity is suppressed. Optical amplifiers are important in optical communication and laser physics. They are used as optical repeaters in the long distance fiber-optic cables which carry much of the world's telecommunication links. There are several different physical mechanisms that can be used to amplify a light signal, which correspond to the major types of optical amplifiers. In doped fiber amplifiers and bulk lasers, stimulated emission in the amplifier's gain medium causes amplification of incoming light. In semiconductor optical amplifiers (SOAs), electron–hole recombination occurs. In Raman amplifiers, Raman scattering of incoming light with phonons in the lattice of the gain medium produces photons coherent with th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A Guiding Star
A, or a, is the first Letter (alphabet), letter and the first vowel letter of the Latin alphabet, used in the modern English alphabet, and others worldwide. Its name in English is ''English alphabet#Letter names, a'' (pronounced ), plural ''aes''. It is similar in shape to the Ancient Greek letter alpha, from which it derives. The uppercase version consists of the two slanting sides of a triangle, crossed in the middle by a horizontal bar. The lowercase version is often written in one of two forms: the double-storey and single-storey . The latter is commonly used in handwriting and fonts based on it, especially fonts intended to be read by children, and is also found in italic type. In English, ''English articles, a'' is the indefinite article, with the alternative form ''an''. Name In English, the name of the letter is the ''long A'' sound, pronounced . Its name in most other languages matches the letter's pronunciation in open syllables. History The earliest know ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phonon
A phonon is a collective excitation in a periodic, elastic arrangement of atoms or molecules in condensed matter, specifically in solids and some liquids. In the context of optically trapped objects, the quantized vibration mode can be defined as phonons as long as the modal wavelength of the oscillation is smaller than the size of the object. A type of quasiparticle in physics, a phonon is an excited state in the quantum mechanical quantization of the modes of vibrations for elastic structures of interacting particles. Phonons can be thought of as quantized sound waves, similar to photons as quantized light waves. The study of phonons is an important part of condensed matter physics. They play a major role in many of the physical properties of condensed matter systems, such as thermal conductivity and electrical conductivity, as well as in models of neutron scattering and related effects. The concept of phonons was introduced in 1930 by Soviet physicist Igor Tamm. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gain (laser)
In laser physics, gain or amplification is a process where the medium transfers part of its energy to the emitted electromagnetic radiation, resulting in an increase in optical power. This is the basic principle of all lasers. Quantitatively, ''gain'' is a measure of the ability of a laser medium to increase optical power. However, overall a laser consumes energy. Definition The gain can be defined as the derivative of logarithm of power ~P~ as it passes through the medium. The factor by which an input beam is amplified by a medium is called the gain and is represented by G. :G = \frac\ln(P)=\frac where ~z~ is the coordinate in the direction of propagation. This equation neglects the effects of the transversal profile of the beam. In the quasi-monochromatic paraxial approximation, the gain can be taken into account with the following equation : 2ik\frac= \Delta_E + 2 \nu E + i G E, where ~\nu~ is variation of index of refraction (Which is supposed to be small), ~E~ is complex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laser Pumping
Laser pumping is the act of energy transfer from an external source into the gain medium of a laser. The energy is absorbed in the medium, producing excited states in its atoms. When for a period of time the number of particles in one excited state exceeds the number of particles in the ground state or a less-excited state, population inversion is achieved. In this condition, the mechanism of stimulated emission can take place and the medium can act as a laser or an optical amplifier. The pump power must be higher than the lasing threshold of the laser. The pump energy is usually provided in the form of light or electric current, but more exotic sources have been used, such as Chemical reaction, chemical or nuclear reactions. Optical pumping Pumping cavities A laser pumped with an arc lamp or a flashlamp is usually pumped through the lateral wall of the lasing medium, which is often in the form of a crystal rod containing a metallic impurity or a glass tube containing a liquid d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Active Gain Medium
The active laser medium (also called a gain medium or lasing medium) is the source of optical gain within a laser. The gain results from the stimulated emission of photons through electronic or molecular transitions to a lower energy state from a higher energy state previously populated by a pump source. Examples of active laser media include: * Certain crystals, typically doped with rare-earth ions (e.g. neodymium, ytterbium, or erbium) or transition metal ions (titanium or chromium); most often yttrium aluminium garnet ( Y3 Al5 O12), yttrium orthovanadate (YVO4), or sapphire (Al2O3); and not often caesium cadmium bromide ( Cs Cd Br3) (solid-state lasers) * Glasses, e.g. silicate or phosphate glasses, doped with laser-active ions; * Gases, e.g. mixtures of helium and neon (HeNe), nitrogen, argon, krypton, carbon monoxide, carbon dioxide, or metal vapors; ( gas lasers) * Semiconductors, e.g. gallium arsenide (GaAs), indium gallium arsenide (InGaAs), or gallium nitride (GaN). * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Network
A computer network is a collection of communicating computers and other devices, such as printers and smart phones. In order to communicate, the computers and devices must be connected by wired media like copper cables, optical fibers, or by wireless communication. The devices may be connected in a variety of network topologies. In order to communicate over the network, computers use agreed-on rules, called communication protocols, over whatever medium is used. The computer network can include personal computers, Server (computing), servers, networking hardware, or other specialized or general-purpose Host (network), hosts. They are identified by network addresses and may have hostnames. Hostnames serve as memorable labels for the nodes and are rarely changed after initial assignment. Network addresses serve for locating and identifying the nodes by communication protocols such as the Internet Protocol. Computer networks may be classified by many criteria, including the tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fiber-optic Communication
Fiber-optic communication is a form of optical communication for transmitting information from one place to another by sending pulses of infrared or visible light through an optical fiber. The light is a form of carrier wave that is modulated to carry information. Fiber is preferred over electrical cabling when high bandwidth, long distance, or immunity to electromagnetic interference is required. This type of communication can transmit voice, video, and telemetry through local area networks or across long distances. Optical fiber is used by many telecommunications companies to transmit telephone signals, internet communication, and cable television signals. Researchers at Bell Labs have reached a record bandwidth–distance product of over kilometers per second using fiber-optic communication. Background First developed in the 1970s, fiber-optics have revolutionized the telecommunications industry and have played a major role in the advent of the Information Age. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
George Gilder
George Franklin Gilder (; born November 29, 1939) is an American investor, author, economist, and co-founder of the Discovery Institute. His 1981 book, '' Wealth and Poverty'', advanced a case for supply-side economics and capitalism during the early months of the Reagan administration. He is the chairman of George Gilder Fund Management, LLC. Early life and education Gilder was born in New York City and raised in New York and Massachusetts. His father, Richard Watson Gilder II, was killed flying in the United States Army Air Forces in World War II when Gilder was two years old. He is a great-grandson of designer Louis Comfort Tiffany. He spent most of his childhood with his mother, Anne Spring Denny (Alsop), and his stepfather, Gilder Palmer, on a dairy farm in Tyringham, Massachusetts. Palmer, a college roommate of his father, was deeply involved with his upbringing, as was the family of David Rockefeller, his godfather. Gilder attended Hamilton School in New York City, Phi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kevin Kimberlin
Kevin Kimberlin is chairman of Spencer Trask & Co., a technology firm. Kimberlin's career includes work with Jonas Salk, Walter Gilbert, John Wennberg and Robert Langer. Technology In 1982, Kimberlin invested in Millicom, a startup selected by the Federal Communications Commission to demonstrate the feasibility of cellular telephony. As advisor to the CEO, he structured the first equity financing for Millicom, which started the Racal–Millicom joint venture —subsequently renamed Vodafone Group plc. Kimberlin co-founded Ciena Corporation with Optelecom and David R. Huber to commercialize the first dense wave division multiplexing ( DWDM) system, powered by Ciena’s patented dual-stage optical amplifier. As the common basis of all high-capacity fiber communications networks around the world, WDM contributed to growth of the Internet and serves as its foundation today. Prior to its public offering, Kimberlin was the sole general partner of Next Level Communications, a br ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
David R
David (; , "beloved one") was a king of ancient Israel and Judah and the Kings of Israel and Judah, third king of the Kingdom of Israel (united monarchy), United Monarchy, according to the Hebrew Bible and Old Testament. The Tel Dan stele, an Canaanite and Aramaic inscriptions, Aramaic-inscribed stone erected by a king of Aram-Damascus in the late 9th/early 8th centuries BCE to commemorate a victory over two enemy kings, contains the phrase (), which is translated as "Davidic line, House of David" by most scholars. The Mesha Stele, erected by King Mesha of Moab in the 9th century BCE, may also refer to the "House of David", although this is disputed. According to Jewish works such as the ''Seder Olam Rabbah'', ''Seder Olam Zutta'', and ''Sefer ha-Qabbalah'' (all written over a thousand years later), David ascended the throne as the king of Judah in 885 BCE. Apart from this, all that is known of David comes from biblical literature, Historicity of the Bible, the historicit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ciena
Ciena Corporation is an American optical networking systems and software company based in Hanover, Maryland. The company has been described as a vital player in optical connectivity. The company reported revenues of $4 billion and more than 8,500 employees, . Gary Smith serves as president and chief executive officer (CEO). Customers include AT&T, Deutsche Telekom, KT Corporation and Verizon Communications. History Ciena was founded in 1992 under the name HydraLite by electrical engineer David R. Huber. Optelecom, an optical networking company and Huber's former employer, provided management assistance and production facilities, and co-founder Kevin Kimberlin provided initial equity capital during the formation of the company. Huber engaged William K. Woodruff & Co. to present the idea to John Bayless at Sevin Rosen in November 1993 which resulted in Sevin Rosen investing $1.25 million in April 1994. William K. Woodruff & Co. was a co-manager of Ciena's IPO in February 1997 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optelecom
Optelecom-NKF, Inc. is an American company that designs, manufactures, and markets high-bandwidth communications products, financial market data information, and business video systems. History The company was founded as Optelecom in 1974 by William Culver and Gordon Gould to build optical networking products utilizing fiber optic cable, optical amplifiers and lasers. Today, it develops fiber optic communications products and laser systems for commercial and military customers. Previous to working together to form Optelecom, Culver was employed at IBM's Federal Systems Division, Quantum Electronics Department while Gould was working at the Polytechnic Institute of Brooklyn, (now the New York University Tandon School of Engineering The New York University Tandon School of Engineering (commonly referred to as Tandon) is the engineering and applied sciences school of New York University. Tandon is the second oldest private engineering and technology school in the United St ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
