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Coherent Effects In Semiconductor Optics
The interaction of matter with light, i.e., electromagnetic fields, is able to generate a coherent superposition of excited quantum states in the material. ''Coherence (physics), Coherent'' denotes the fact that the material excitations have a well defined Phase (waves), phase relation which originates from the phase of the incident electromagnetic wave. Macroscopically, the superposition principle, superposition state of the material results in an optical Polarization (waves), polarization, i.e., a rapidly oscillating dipole density. The optical polarization is a genuine non-equilibrium quantity that decays to zero when the excited system relaxes to its equilibrium state after the electromagnetic pulse is switched off. Due to this decay which is called ''dephasing'', coherent effects are observable only for a certain temporal duration after pulsed photoexcitation. Various materials such as atoms, molecules, metals, insulators, semiconductors are studied using coherent optical spec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electromagnetic Fields
In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields. The electromagnetic force is one of the four fundamental forces of nature. It is the dominant force in the interactions of atoms and molecules. Electromagnetism can be thought of as a combination of electrostatics and magnetism, which are distinct but closely intertwined phenomena. Electromagnetic forces occur between any two charged particles. Electric forces cause an attraction between particles with opposite charges and repulsion between particles with the same charge, while magnetism is an interaction that occurs between charged particles in relative motion. These two forces are described in terms of electromagnetic fields. Macroscopic charged objects are described in terms of Coulomb's law for electricity and Ampère's force law for magnetism; the Lorentz force describes microscopic charged particles. The electromagnetic force is responsible for ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Population Inversion
In physics, specifically statistical mechanics, a population inversion occurs when a system (such as a group of atoms or molecules) exists in a state in which more members of the system are in higher, excited states than in lower, unexcited energy states. It is called an "inversion" because in many familiar and commonly encountered physical systems in thermal equilibrium, this is not possible. This concept is of fundamental importance in laser science because the production of a population inversion is a necessary step in the workings of a standard laser. Boltzmann distributions and thermal equilibrium To understand the concept of a population inversion, it is necessary to understand some thermodynamics and the way that light interacts with matter. To do so, it is useful to consider a very simple assembly of atoms forming a laser medium. Assume there is a group of ''N'' atoms, each of which is capable of being in one of two energy states: either # The ''ground state'', with ene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semiconductor Luminescence Equations
The semiconductor luminescence equations (SLEs)Kira, M.; Jahnke, F.; Koch, S.; Berger, J.; Wick, D.; Nelson, T.; Galina Khitrova, Khitrova, G.; Gibbs, H. (1997). "Quantum Theory of Nonlinear Semiconductor Microcavity Luminescence Explaining "Boser" Experiments". ''Physical Review Letters'' 79 (25): 5170–5173. doi:10.1103/PhysRevLett.79.5170Kira, M.; Koch, S. W. (2011). ''Semiconductor Quantum Optics''. Cambridge University Press. . describe luminescence of semiconductors resulting from spontaneous Carrier generation and recombination, recombination of electronic excitations, producing a Luminous flux, flux of Spontaneous emission, spontaneously emitted light. This description established the first step toward semiconductor quantum optics because the SLEs simultaneously includes the quantized light–matter interaction and the Coulomb's law, Coulomb-interaction coupling among electronic excitations within a semiconductor. The SLEs are one of the most accurate methods to describe li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semiconductor Quantum Optics With Dots
A semiconductor is a material with electrical conductivity between that of a conductor and an insulator. Its conductivity can be modified by adding impurities (" doping") to its crystal structure. When two regions with different doping levels are present in the same crystal, they form a semiconductor junction. The behavior of charge carriers, which include electrons, ions, and electron holes, at these junctions is the basis of diodes, transistors, and most modern electronics. Some examples of semiconductors are silicon, germanium, gallium arsenide, and elements near the so-called "metalloid staircase" on the periodic table. After silicon, gallium arsenide is the second-most common semiconductor and is used in laser diodes, solar cells, microwave-frequency integrated circuits, and others. Silicon is a critical element for fabricating most electronic circuits. Semiconductor devices can display a range of different useful properties, such as passing current more easily in one di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Optics
Quantum optics is a branch of atomic, molecular, and optical physics and quantum chemistry that studies the behavior of photons (individual quanta of light). It includes the study of the particle-like properties of photons and their interaction with, for instance, atoms and molecules. Photons have been used to test many of the counter-intuitive predictions of quantum mechanics, such as entanglement and teleportation, and are a useful resource for quantum information processing. History Light propagating in a restricted volume of space has its energy and momentum quantized according to an integer number of particles known as photons. Quantum optics studies the nature and effects of light as quantized photons. The first major development leading to that understanding was the correct modeling of the blackbody radiation spectrum by Max Planck in 1899 under the hypothesis of light being emitted in discrete units of energy. The photoelectric effect was further evidence of thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terahertz Spectroscopy And Technology
Terahertz spectroscopy detects and controls properties of matter with electromagnetic fields that are in the frequency range between a few hundred gigahertz and several terahertz (abbreviated as THz). In many-body systems, several of the relevant states have an energy difference that matches with the energy of a THz photon. Therefore, THz spectroscopy provides a particularly powerful method in resolving and controlling individual transitions between different many-body states. By doing this, one gains new insights about many-body quantum kinetics and how that can be utilized in developing new technologies that are optimized up to the elementary quantum level. Different electronic excitations within semiconductors are already widely used in lasers, electronic components and computers. At the same time, they constitute an interesting many-body system whose quantum properties can be modified, e.g., via a nanostructure design. Consequently, THz spectroscopy on semiconductors is releva ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terahertz Radiation
Terahertz radiation – also known as submillimeter radiation, terahertz waves, tremendously high frequency (THF), T-rays, T-waves, T-light, T-lux or THz – consists of electromagnetic waves within the International Telecommunication Union-designated band of Frequency, frequencies from 0.1 to 10 Hertz#SI prefixed forms of hertz, terahertz (THz), (from 0.3 to 3 Hertz#SI prefixed forms of hertz, terahertz (THz) in older texts, which is now called "decimillimetric waves" ), although the upper boundary is somewhat arbitrary and has been considered by some sources to be 30 THz. One terahertz is 1012 Hertz, Hz or 1,000 GHz. Wavelengths of radiation in the decimillimeter band correspondingly range 1 mm to 0.1 mm = 100 μm and those in the terahertz band 3 mm = 3000 μm to 30 μm. Because terahertz radiation begins at a wavelength of around 1 millimeter and proceeds into shorter wavelengths, it is sometimes kno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galina Khitrova
Galina Khitrova (1959 – June 4, 2016) was a Russian-American physicist and optical scientist known for her research on cavity quantum electrodynamics, excitons, nonlinear optics, quantum dots, and vacuum Rabi oscillations. She was a professor of optical sciences at the University of Arizona. Education and career Khitrova was born in Saint Petersburg, and has degrees in physics from Yerevan State University, Brooklyn College, and New York University, where she completed her Ph.D. She came to the University of Arizona as a researcher in 1986, married Arizona professor Professor Hyatt M. Gibbs in 1986, was given tenure as an associate professor in 1997, and became full professor in 2002. Recognition Khitrova was named a Fellow of The Optical Society in 2007, "for leadership in research in fundamental optical phenomena in semiconductor nanostructures". She was named a Fellow of the American Physical Society The American Physical Society honors members with the designation ''Fello ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nanostructures
A nanostructure is a structure of intermediate size between microscopic and molecular structure A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as ...s. Nanostructural detail is microstructure at nanoscale. In describing nanostructures, it is necessary to differentiate between the number of dimensions in the volume of an object which are on the nanoscale. Nanotextured surfaces have ''one dimension'' on the nanoscale, i.e., only the thickness of the surface of an object is between 0.1 and 100 nm. Nanotubes have ''two dimensions'' on the nanoscale, i.e., the diameter of the tube is between 0.1 and 100 nm; its length can be far more. Finally, spherical nanoparticles have ''three dimensions'' on the nanoscale, i.e., the particle is between 0.1 and 100 nm in each spat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squared Modulus
In mathematics, a square is the result of multiplying a number by itself. The verb "to square" is used to denote this operation. Squaring is the same as raising to the power 2, and is denoted by a superscript 2; for instance, the square of 3 may be written as 32, which is the number 9. In some cases when superscripts are not available, as for instance in programming languages or plain text files, the notations ''x''^2 (caret) or ''x''**2 may be used in place of ''x''2. The adjective which corresponds to squaring is '' quadratic''. The square of an integer may also be called a ''square number'' or a ''perfect square''. In algebra, the operation of squaring is often generalized to polynomials, other expressions, or values in systems of mathematical values other than the numbers. For instance, the square of the linear polynomial is the quadratic polynomial . One of the important properties of squaring, for numbers as well as in many other mathematical systems, is that (for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Femtoseconds
A femtosecond is a unit of time in the International System of Units (SI) equal to 10 or of a second; that is, one quadrillionth, or one millionth of one billionth, of a second. A femtosecond is to a second, as a second is to approximately 31.69 million years. For context, a ray of light travels approximately 0.3 μm (micrometers) in 1 femtosecond, a distance comparable to the diameter of a virus.Compared with overview in: The first to make femtosecond measurements was the Egyptian Nobel Laureate Ahmed Zewail, for which he was awarded the Nobel Prize in Chemistry in 1999. Professor Zewail used lasers to measure the movement of particles at the femtosecond scale, thereby allowing chemical reactions to be observed for the first time. The word ''femtosecond'' is formed by the SI prefix ''femto'' and the SI unit ''second''. Its symbol is fs. A femtosecond is equal to 1000 attoseconds, or 1/1000 picosecond. Because the next higher SI unit is 1000 times larger, times of 10� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semiconductor Laser Theory
Semiconductor lasers or laser diodes play an important part in our everyday lives by providing cheap and compact-size lasers. They consist of complex multi-layer structures requiring nanometer scale accuracy and an elaborate design. Their theoretical description is important not only from a fundamental point of view, but also in order to generate new and improved designs. It is common to all systems that the laser is an inverted carrier density system. The charge carrier, carrier inversion results in an Electromagnetic radiation, electromagnetic Polarization density, polarization which drives an electric field E(t). In most cases, the electric field is confined in a resonator, the properties of which are also important factors for laser performance. Gain medium In semiconductor laser theory, the Semiconductor optical gain, optical gain is produced in a semiconductor material. The choice of material depends on the desired wavelength and properties such as modulation speed. It ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
