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Coherent Addition
Coherent addition (or coherent combining) of lasers is a method of power scaling. It allows increasing the output power and brightness of single-transversal mode laser. Usually, the term coherent addition applies to fiber lasers. As the ability of pumping and/or cooling of a single laser is saturated, several similar lasers can be forced to oscillate in phase with a common coupler. The first nonlinear theory of the coherent addition of laser sets had been developed by Nikolay Basov with co-workers in 1965. For Nd:YAG laser set beam combination had been realized by means of SBS phase conjugating mirror. The coherent addition was demonstrated in power scaling of Raman lasers. Limits of coherent addition The addition of lasers reduces the number of longitudinal modes in the output beam; the more lasers are combined, the smaller is the number of longitudinal modes in the output. The simple estimates show that the number of output modes reduces exponentially with the number of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word ''laser'' originated as an acronym for light amplification by stimulated emission of radiation. The first laser was built in 1960 by Theodore Maiman at Hughes Research Laboratories, based on theoretical work by Charles H. Townes and Arthur Leonard Schawlow and the optical amplifier patented by Gordon Gould. A laser differs from other sources of light in that it emits light that is coherence (physics), ''coherent''. Spatial coherence allows a laser to be focused to a tight spot, enabling uses such as optical communication, laser cutting, and Photolithography#Light sources, lithography. It also allows a laser beam to stay narrow over great distances (collimated light, collimation), used in laser pointers, lidar, and free-space optical communication. Lasers can also have high temporal coherence, which permits them to emit light ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mode Locking
Mode locking is a technique in optics by which a laser can be made to produce pulses of light of extremely short duration, on the order of picoseconds (10−12 s) or femtoseconds (10−15 s). A laser operated in this way is sometimes referred to as a femtosecond laser, for example, in modern refractive surgery. The basis of the technique is to induce a fixed phase relationship between the longitudinal modes of the laser's resonant cavity. Constructive interference between these modes can cause the laser light to be produced as a train of pulses. The laser is then said to be "phase-locked" or "mode-locked". Laser cavity modes Although laser light is perhaps the purest form of light, it is not of a single, pure frequency or wavelength. All lasers produce light over some natural bandwidth or range of frequencies. A laser's bandwidth of operation is determined primarily by the gain medium from which the laser is constructed, and the range of frequencies over which a lase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Laser Articles
This is a list of laser topics. A * 3D printing, additive manufacturing * Abnormal reflection * Above-threshold ionization * Absorption spectroscopy * Accelerator physics * Acoustic microscopy * Acousto-optic deflector * Acousto-optic modulator * Acousto-optical spectrometer * Acousto-optics * Active laser medium * Active optics * Advanced Precision Kill Weapon System * Advanced Tactical Laser * Afocal system * Airborne laser * Airborne wind turbine * Airy beam * ALKA * All gas-phase iodine laser * Ambient ionization * Amplified spontaneous emission * Analytical chemistry * Aneutronic fusion * Antiproton Decelerator * Apache Arrowhead * Apache Point Observatory Lunar Laser-ranging Operation * Arago spot * Argon fluoride laser * Argus laser * Asterix IV laser * Astrophysical maser * Atmospheric-pressure laser ionization * Atom interferometer * Atom laser * Atom probe * Atomic clock * Atomic coherence * Atomic fountain * Atomic line filter * Ato ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BAE Systems Tempest
The BAE Systems Tempest is a proposed sixth-generation fighter aircraft that is under development in the United Kingdom for the Royal Air Force (RAF). The aircraft is intended to enter service from 2035, gradually replacing the Eurofighter Typhoon. It is being developed as part of the Future Combat Air System (FCAS) programme by a consortium known as Team Tempest, which includes the Ministry of Defence, BAE Systems, Rolls-Royce, the UK subsidiary of Leonardo, and MBDA UK. £2 billion is planned to be spent by the British government on the initial phase of the project up to 2025. Both Italy and Sweden signed a Memorandum of Understanding in 2020 committing to explore collaboration on the FCAS programme. The UK and Japan announced they are working together on the joint development of engine and radar demonstrators. This was followed by an announcement in December 2022 of the Global Combat Air Programme (GCAP); a collaboration between Italy, Japan and the UK for a sixth-gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Air Force
The Royal Air Force (RAF) is the Air force, air and space force of the United Kingdom, British Overseas Territories and Crown Dependencies. It was formed towards the end of the World War I, First World War on 1 April 1918, on the merger of the Royal Flying Corps (RFC) and the Royal Naval Air Service (RNAS). Following the Allies of World War I, Allied victory over the Central Powers in 1918, the RAF emerged as the largest air force in the world at the time. Since its formation, the RAF has played History of the Royal Air Force, a significant role in Military history of the United Kingdom, British military history. In particular, during the Second World War, the RAF established Air supremacy, air superiority over Nazi Germany's Luftwaffe during the Battle of Britain, and led the Allied strategic bombing effort. The RAF's mission is to support the objectives of the British Ministry of Defence (United Kingdom), Ministry of Defence (MOD), which are to "provide the capabilities nee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Army
The British Army is the principal Army, land warfare force of the United Kingdom. the British Army comprises 73,847 regular full-time personnel, 4,127 Brigade of Gurkhas, Gurkhas, 25,742 Army Reserve (United Kingdom), volunteer reserve personnel and 4,697 "other personnel", for a total of 108,413. The British Army traces back to 1707 and the Acts of Union 1707, formation of the united Kingdom of Great Britain which joined the Kingdoms of Kingdom of England, England and Kingdom of Scotland, Scotland into a Political union, single state and, with that, united the English Army and the Scots Army as the British Army. The Parliament of England, English Bill of Rights 1689 and Convention of the Estates, Scottish Claim of Right Act 1689 require parliamentary consent for the Crown to maintain a peacetime standing army. Members of the British Army swear allegiance to the Charles III, monarch as their commander-in-chief. The army is administered by the Ministry of Defence (United Kingd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Navy
The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King of the United Kingdom, King. Although warships were used by Kingdom of England, English and Kingdom of Scotland, Scottish kings from the early Middle Ages, medieval period, the first major maritime engagements were fought in the Hundred Years' War against Kingdom of France, France. The modern Royal Navy traces its origins to the English Navy of the early 16th century; the oldest of the British Armed Forces, UK's armed services, it is consequently known as the Senior Service. From the early 18th century until the World War II, Second World War, it was the world's most powerful navy. The Royal Navy played a key part in establishing and defending the British Empire, and four Imperial fortress colonies and a string of imperial bases and coaling stations secured the Royal Navy's ability to assert naval superior ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dragonfire (weapon)
DragonFire is a British laser directed-energy weapon (LDEW) in development for the Royal Navy. It was first unveiled to the public as a technology demonstrator in 2017 at the Defence and Security Equipment International (DSEI) conference in London and is being developed by UK DragonFire, a collaboration consisting of MBDA UK, Leonardo UK, QinetiQ and the Defence Science and Technology Laboratory (dstl). A production version is expected to enter service onboard Royal Navy ships in 2027. Development The weapon was first shown publicly at the 2017 DSEI conference in London. Development of the technology demonstrator was to be carried out by a partnership between the British Ministry of Defence (MOD) and private industry. UK DragonFire is the result of contracts worth £100 million – of which £30 million was awarded by the MoD's Chief Scientific Advisor's Research Programme – from various companies, led by MBDA UK with QinetiQ, Leonardo, GKN, Arke, BAE Systems and Marshall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Talbot Cavity
A Talbot cavity is an external cavity used for the coherent beam combination of output from laser sets. It has been used experimentally for semiconductor laser diodes, carbon dioxide lasers, fiber lasers and solid-state disk lasers arranged in an array. In the simplest version, it is constructed with a single mirror at half the Talbot distance from the output facet of the laser array: z_=\frac, where p is the period of the laser lattice and \lambda is the wavelength of laser emission. The constructive interference images the near field of the array back onto the array itself at the Talbot distance, creating optical feedback. This interference feedback forces the lasers in the array to transverse mode lock. The Fresnel number In optics, in particular scalar diffraction theory, the Fresnel number (), named after the physicist Augustin-Jean Fresnel, is a dimensionless number relating to the pattern a beam of light forms on a surface when projected through an aperture ... F of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fresnel Number
In optics, in particular scalar diffraction theory, the Fresnel number (), named after the physicist Augustin-Jean Fresnel, is a dimensionless number relating to the pattern a beam of light forms on a surface when projected through an aperture. Definition For an electromagnetic wave passing through an aperture and hitting a screen, the Fresnel number ''F'' is defined as : F = \frac where : a is the characteristic size (e.g. radius) of the aperture : L is the distance of the screen from the aperture : \lambda is the incident wavelength. Conceptually, it is the number of half- period zones in the wavefront amplitude, counted from the center to the edge of the aperture, as seen from the observation point (the center of the imaging screen), where a half-period zone is defined so that the wavefront phase changes by \pi when moving from one half-period zone to the next. An equivalent definition is that the Fresnel number is the difference, expressed in half-wavelengths, between ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chirped Pulse Amplification
Chirped pulse amplification (CPA) is a technique for amplifying an ultrashort laser pulse up to the petawatt level, with the laser pulse being stretched out temporally and spectrally, then amplified, and then compressed again. The stretching and compression uses devices that ensure that the different color components of the pulse travel different distances. CPA for lasers was introduced by Donna Strickland and Gérard Mourou at the University of Rochester in the mid-1980s, work for which they received the Nobel Prize in Physics in 2018. CPA is the technique used by most high-powered lasers in the world. Background Before the introduction of CPA in the mid-1980s, the peak power of laser pulses was limited because a laser pulse at intensities of gigawatts per square centimeter causes serious damage to the gain medium through nonlinear processes such as self-focusing. For example, some of the most powerful compressed CPA laser beams, even in an unfocused large aperture (afte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power Scaling
Power scaling of a laser is increasing its output power without changing the geometry, shape, or principle of operation. Power scalability is considered an important advantage in a laser design. This means it can increase power without changing outside features. Usually, power scaling requires a more powerful laser pumping, pump source, stronger cooling, and an increase in size. It may also require reduction of the background loss in the optical resonator, laser resonator and, in particular, in the gain medium. Master Oscillator Power Amplifier (MOPA) One way of achieving power scalability is the MOPA approach. The master oscillator (a seed laser to be amplified) produces a highly coherent beam, and an optical amplifier is used to increase the power of the beam while preserving its main properties. The master oscillator has no need to be powerful, and has no need to operate at high efficiency because the efficiency is determined mainly by the power amplifier. The combination of seve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
