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Coupling Parameter
The coupling parameter of the resonator specifies the part of the energy of the laser field, which is output at each round-trip. The coupling parameter should not be confused with the round-trip loss, which refers to the part of the energy which is absorbed or scattered at each round-trip of laser field in the laser resonator, and cannot be used. At the continuous wave operation, the round-trip gain is determined by the coupling parameter and the round-trip loss. In simple configurations of the laser cavity or laser resonator, the coupling parameter may be just the transmission coefficient of the output coupler or just square of the magnification coefficient in the case of an unstable resonator. The round-trip loss may limit the power scaling of the active mirrors, or disk lasers, while the size of the gain medium scales up, and the gain size product is limited by the exponential growth of the amplified spontaneous emission; the powerful disk laser should work at low values of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Round-trip Loss
Round-trip gain refers to the laser physics, and laser cavities (or laser resonators). It is gain, integrated along a ray, which makes a round-trip in the cavity. At the continuous-wave operation, the round-trip gain exactly compensates both the output coupling of the cavity and its background loss. Round-trip gain in geometric optics Generally, the Round-trip gain may depend on the frequency, on the position and tilt of the ray, and even on the polarization of light. Usually, we may assume that at some moment of time, at reasonable frequency of operation, the gain ~G(x,y,z)~ is function of the Cartesian coordinates ~x~, ~y~, and ~z~. Then, assuming that the geometrical optics is applicable the round-trip gain ~g~ can be expressed as follows: :~g=\int G(x(a),y(a),z(a))~a~, where ~a~ is path along the ray, parametrized with functions ~x(a)~, ~y(a)~, ~z(a)~; the integration is performed along the whole ray, which is supposed to form the closed loop. In simple models, the flat-to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laser Resonator
An optical cavity, resonating cavity or optical resonator is an arrangement of mirrors or other optical elements that forms a cavity resonator for light waves. 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 cavity 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 chosen so that the beam remains stable, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Round-trip Gain
Round-trip gain refers to the laser physics, and laser cavities (or laser resonators). It is gain, integrated along a ray, which makes a round-trip in the cavity. At the continuous-wave operation, the round-trip gain exactly compensates both the output coupling of the cavity and its background loss. Round-trip gain in geometric optics Generally, the Round-trip gain may depend on the frequency, on the position and tilt of the ray, and even on the polarization of light. Usually, we may assume that at some moment of time, at reasonable frequency of operation, the gain ~G(x,y,z)~ is function of the Cartesian coordinates A Cartesian coordinate system (, ) in a plane is a coordinate system that specifies each point uniquely by a pair of numerical coordinates, which are the signed distances to the point from two fixed perpendicular oriented lines, measured in t ... ~x~, ~y~, and ~z~. Then, assuming that the geometrical optics is applicable the round-trip gain ~g~ can be expressed ... [...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 forms a cavity resonator for light waves. 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 cavity 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 chosen so that the beam remains stable, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnification Coefficient
Magnification is the process of enlarging the angular diameter, apparent size, not physical size, of something. This enlargement is quantified by a calculated number also called "magnification". When this number is less than one, it refers to a reduction in size, sometimes called ''minification'' or ''de-magnification''. Typically, magnification is related to scaling up visuals or images to be able to see more detail, increasing angular resolution, resolution, using microscope, printing techniques, or digital processing. In all cases, the magnification of the image does not change the perspective (graphical), perspective of the image. Examples of magnification Some optical instruments provide visual aid by magnifying small or distant subjects. * A magnifying glass, which uses a Lens (optics), positive (convex) lens to make things look bigger by allowing the user to hold them closer to their eye. * A telescope, which uses its large Objective (optics), objective lens or primary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unstable Resonator
In numerous fields of study, the component of instability within a system is generally characterized by some of the outputs or internal states growing without bounds. Not all systems that are not stable are unstable; systems can also be marginally stable or exhibit limit cycle behavior. In structural engineering, a structure can become unstable when excessive load is applied. Beyond a certain threshold, structural deflections magnify stresses, which in turn increases deflections. This can take the form of buckling or crippling. The general field of study is called structural stability. Atmospheric instability is a major component of all weather systems on Earth. Instability in control systems In the theory of dynamical systems, a state variable in a system is said to be unstable if it evolves without bounds. A system itself is said to be unstable if at least one of its state variables is unstable. In continuous time control theory, a system is unstable if any of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Active Mirror
A disk laser or active mirror (Fig.1) is a type of diode pumped solid-state laser characterized by a heat sink and laser output that are realized on opposite sides of a thin layer of active gain medium. Despite their name, disk lasers do not have to be circular; other shapes have also been tried. The thickness of the disk is considerably smaller than the laser beam diameter. Initially, this laser cavity configuration had been proposed and realized experimentally for thin slice semiconductor lasers. The disk laser concepts allow very high average and peak powers due to its large area, leading to moderate power densities on the active material. Active mirrors and disk lasers Initially, disk lasers were called ''active mirrors'', because the gain medium of a disk laser is essentially an optical mirror with reflection coefficient greater than unity. An active mirror is a thin disk-shaped double-pass optical amplifier. The first active mirrors were developed in the Laboratory fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disk Laser
A disk laser or active mirror (Fig.1) is a type of diode pumped solid-state laser characterized by a heat sink and laser output that are realized on opposite sides of a thin layer of active gain medium. Despite their name, disk lasers do not have to be circular; other shapes have also been tried. The thickness of the disk is considerably smaller than the laser beam diameter. Initially, this laser cavity configuration had been proposed and realized experimentally for thin slice semiconductor lasers. The disk laser concepts allow very high average and peak powers due to its large area, leading to moderate power densities on the active material. Active mirrors and disk lasers Initially, disk lasers were called ''active mirrors'', because the gain medium of a disk laser is essentially an optical mirror with reflection coefficient greater than unity. An active mirror is a thin disk-shaped double-pass optical amplifier. The first active mirrors were developed in the Laboratory fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gain Medium
The active laser medium (also called 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). * Liqu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amplified Spontaneous Emission
Amplified spontaneous emission (ASE) or superluminescence is light, produced by spontaneous emission, that has been optically amplified by the process of stimulated emission in a gain medium. It is inherent in the field of random lasers. Origins ASE is produced when a laser gain medium is pumped to produce a population inversion. Feedback of the ASE by the laser's optical cavity may produce laser operation if the lasing threshold is reached. Excess ASE is an unwanted effect in lasers, since it is not coherent, and limits the maximum gain that can be achieved in the gain medium. ASE creates serious problems in any laser with high gain and/or large size. In this case, a mechanism to absorb or extract the incoherent ASE must be provided, otherwise the excitation of the gain medium will be depleted by the incoherent ASE rather than by the desired coherent laser radiation. ASE is especially problematic in lasers with short and wide optical cavities, such as disk lasers (active mirro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disk Laser
A disk laser or active mirror (Fig.1) is a type of diode pumped solid-state laser characterized by a heat sink and laser output that are realized on opposite sides of a thin layer of active gain medium. Despite their name, disk lasers do not have to be circular; other shapes have also been tried. The thickness of the disk is considerably smaller than the laser beam diameter. Initially, this laser cavity configuration had been proposed and realized experimentally for thin slice semiconductor lasers. The disk laser concepts allow very high average and peak powers due to its large area, leading to moderate power densities on the active material. Active mirrors and disk lasers Initially, disk lasers were called ''active mirrors'', because the gain medium of a disk laser is essentially an optical mirror with reflection coefficient greater than unity. An active mirror is a thin disk-shaped double-pass optical amplifier. The first active mirrors were developed in the Laboratory fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
