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Fiber Laser
A fiber laser (or fibre laser in Commonwealth English) is a laser in which the active gain medium is an optical fiber doped with rare-earth elements such as erbium, ytterbium, neodymium, dysprosium, praseodymium, thulium and holmium. They are related to doped fiber amplifiers, which provide light amplification without lasing. Fiber nonlinearities, such as stimulated Raman scattering or four-wave mixing, can also provide gain and thus serve as gain media for a fiber laser. Characteristics An advantage of fiber lasers over other types of lasers is that the laser light is both generated and delivered by an inherently flexible medium, which allows easier delivery to the focusing location and target. This can be important for laser cutting, welding, and folding of metals and polymers. Another advantage is high output power compared to other types of laser. Fiber lasers can have active regions several kilometers long, and so can provide very high optical gain. They can sup ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commonwealth English
The use of the English language in current and former Member states of the Commonwealth of Nations, countries of Commonwealth of Nations, the Commonwealth was largely inherited from British Empire, British colonisation, with some exceptions. English forms part of the Commonwealth's Commonwealth of Nations#Culture, common culture and serves as the medium of inter-Commonwealth relations. ''Commonwealth English'' wikt:Commonwealth_English, refers to English as practised in the Commonwealth; the term is most often interchangeable with ''British English'', but is also used to distinguish between British English and that in the rest of the Commonwealth. English in the Commonwealth is diverse, and many regions have developed their own local varieties of the language. The Official language, official status of English varies; in Bangladeshi English, Bangladesh, it lacks any but is widely used, and likewise in Languages of Cyprus, Cyprus, it is not official but is used as the . Written En ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Area
The surface area (symbol ''A'') of a solid object is a measure of the total area that the surface of the object occupies. The mathematical definition of surface area in the presence of curved surfaces is considerably more involved than the definition of arc length of one-dimensional curves, or of the surface area for polyhedra (i.e., objects with flat polygonal faces), for which the surface area is the sum of the areas of its faces. Smooth surfaces, such as a sphere, are assigned surface area using their representation as parametric surfaces. This definition of surface area is based on methods of infinitesimal calculus and involves partial derivatives and double integration. A general definition of surface area was sought by Henri Lebesgue and Hermann Minkowski at the turn of the twentieth century. Their work led to the development of geometric measure theory, which studies various notions of surface area for irregular objects of any dimension. An important example is ... [...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] |
Distributed Feedback Laser
A distributed-feedback laser (DFB) is a type of laser diode, quantum-cascade laser or optical-fiber laser where the active region of the device contains a periodically structured element or diffraction grating. The structure builds a one-dimensional interference grating ( Bragg scattering), and the grating provides optical feedback for the laser. This longitudinal diffraction grating has periodic changes in refractive index that cause reflection back into the cavity. The periodic change can be either in the real part of the refractive index or in the imaginary part (gain or absorption). The strongest grating operates in the first order, where the periodicity is one-half wave, and the light is reflected backwards. DFB lasers tend to be much more stable than Fabry–Perot or DBR lasers and are used frequently when clean single-mode operation is needed, especially in high-speed fiber-optic telecommunications. Semiconductor DFB lasers in the lowest loss window of optical fibers at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Feedback
Optical feedback (OF) refers to the phenomenon in a laser, where a part of the coherent emission light returns to the laser cavity. The effect is typical for any laser, although the cause of the feedback light varies: reflection from optical components, fiber edges, spectroscopy cell windows. Operation of the semiconductor laser is very sensitive to OF due to its very high intrinsic gain and chirping effect, as well as the relaxation oscillation. Upon return, the feedback light will be delayed with respect to the light in the cavity, and will have different phase, thus either amplifying or suppressing the laser output. While the recombination of the feedback light and light already in the cavity is usually linear, the delay, high gain, chirping, and relaxation oscillation create complex dynamic effects at the output. In the case of the optical resonator, this is accomplished by parallel mirrors which cause light to be reflected within the lasing cavity, allowing for a single p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dielectric Mirror
A dielectric mirror, also known as a Bragg mirror, is a type of mirror composed of multiple thin film, thin layers of dielectric material, typically deposited on a substrate of glass or some other optical material. By careful choice of the type and thickness of the dielectric layers, one can design an optical coating with specified reflectivity at different wavelengths of light. Dielectric mirrors are also used to produce ultra-high reflectivity mirrors: values of 99.999% or better over a narrow range of wavelengths can be produced using special techniques. Alternatively, they can be made to reflect a broad spectrum of light, such as the entire visible range or the spectrum of the Ti-sapphire laser. Dielectric mirrors are very common in optics experiments, due to improved techniques that allow inexpensive manufacture of high-quality mirrors. Examples of their applications include laser optical cavity, cavity end mirrors, Hot mirror, hot and cold mirrors, thin-film beam splitter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fiber Bragg Grating
A fiber Bragg grating (FBG) is a type of distributed Bragg reflector constructed in a short segment of optical fiber that reflects particular wavelengths of light and transmits all others. This is achieved by creating a periodic variation in the refractive index of the fiber core, which generates a wavelength-specific dielectric mirror. Hence a fiber Bragg grating can be used as an inline optical filter to block certain wavelengths, can be used for sensing applications, or it can be used as wavelength-specific reflector. History The first in-fiber Bragg grating was demonstrated by Kenneth O. Hill, Ken Hill in 1978. Initially, the gratings were fabricated using a visible laser propagating along the fiber core. In 1989, Gerald Meltz and colleagues demonstrated the much more flexible transverse holographic inscription technique where the laser illumination came from the side of the fiber. This technique uses the #Interference, interference pattern of ultraviolet laser light to cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fusion Splicing
Fusion splicing is the act of joining two optical fibers end-to-end. The goal is to fuse the two fibers together in such a way that light passing through the fibers is not scattered or reflected back by the splice, and so that the splice and the region surrounding it are almost as strong as the intact fiber. The source of heat used to melt and fuse the two glass fibers being spliced is usually an electric arc, but can also be a laser, a gas flame, or a tungsten filament through which current is passed. Governing standards ANSI/EIA/TIA-455 See also * Fiber-optic communication * Optical fiber connector An optical fiber connector is a device used to link optical fibers, facilitating the efficient transmission of light signals. An optical fiber connector enables quicker connection and disconnection than splicing. They come in various types li ... * Optical time-domain reflectometer References * Further reading * "How to Precision Clean All Fiber Optic Connection ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laser Cavity
An optical cavity, resonating cavity or optical resonator is an arrangement of mirrors or other optical elements that confines light waves similarly to how a cavity resonator confines microwaves. Optical cavities are a major component of lasers, surrounding the gain medium and providing feedback of the laser light. They are also used in optical parametric oscillators and some interferometers. Light confined in the cavity reflects multiple times, producing modes with certain resonance frequencies. Modes can be decomposed into longitudinal modes that differ only in frequency and transverse modes that have different intensity patterns across the cross section of the beam. Many types of optical cavities produce standing wave modes. Different resonator types are distinguished by the focal lengths of the two mirrors and the distance between them. Flat mirrors are not often used because of the difficulty of aligning them to the needed precision. The geometry (resonator type) must be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cost Of Ownership
Cost is the value of money that has been used up to produce something or deliver a service, and hence is not available for use anymore. In business, the cost may be one of acquisition, in which case the amount of money expended to acquire it is counted as cost. In this case, money is the input that is gone in order to acquire the thing. This acquisition cost may be the sum of the cost of production as incurred by the original producer, and further costs of transaction as incurred by the acquirer over and above the price paid to the producer. Usually, the price also includes a mark-up for profit over the cost of production. More generalized in the field of economics, cost is a performance metric, metric that is totaling up as a result of a process or as a differential for the result of a Decision making, decision. Hence cost is the metric used in the standard Business process modelling, modeling paradigm applied to economic Business process, processes. Costs (pl.) are often fur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gas Laser
A gas laser is a laser in which an electric current is discharged through a gas to produce coherent light. The gas laser was the first continuous-light laser and the first laser to operate on the principle of converting electrical energy to a laser light output. The first gas laser, the Helium–neon laser (HeNe), was co-invented by Iranian engineer and scientist Ali Javan and American physicist William R. Bennett, Jr., in 1960. It produced a coherent light beam in the infrared region of the spectrum at 1.15 micrometres. Types of gas laser Gas lasers using many gases have been built and used for many purposes. Carbon dioxide lasers, or lasers can emit hundreds of kilowatts at 9.6 μm and 10.6 μm, and are often used in industry for cutting and welding. The efficiency of a laser is over 10%. Carbon monoxide or "CO" lasers have the potential for very large outputs, but the use of this type of laser is limited by the toxicity of carbon monoxide gas. Human op ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solid-state Laser
A solid-state laser is a laser that uses a active laser medium, gain medium that is a solid, rather than a liquid as in dye lasers or a gas as in gas lasers. Semiconductor-based lasers are also in the solid state, but are generally considered as a separate class from solid-state lasers, called laser diodes. Solid-state media Generally, the active medium of a solid-state laser consists of a glass or crystalline "host" material, to which is added a "dopant" such as neodymium, chromium, erbium, thulium or ytterbium.Z. Su, J. D. Bradley, N. Li, E. S. Magden, Purnawirman, D. Coleman, N. Fahrenkopf, C. Baiocco, T. Adam, G. Leake, D. Coolbaugh, D. Vermeulen, and M. R. Watts (2016"Ultra-Compact CMOS-Compatible Ytterbium Microlaser" ''Integrated Photonics Research, Silicon and Nanophotonics 2016'', IW1A.3. Many of the common dopants are rare-earth elements, because the excited states of such ions are not strongly coupled with the thermal vibrations of their crystal lattices (phonons), and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
