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Potassium Titanyl Phosphate
Potassium titanyl phosphate (KTP) is an inorganic compound with the formula . It is a white solid. KTP is an important nonlinear optics, nonlinear optical material that is commonly used for second-harmonic generation, frequency-doubling diode-pumped solid-state lasers such as Nd:YAG laser, Nd:YAG and other neodymium-doped lasers. Synthesis and structure The compound is prepared by the reaction of titanium dioxide with a mixture of KH2PO4 and K2HPO4 near 1300 K. The potassium salts serve both as reagents and flux. The material has been characterized by X-ray crystallography. KTP has an orthorhombic crystal structure. It features octahedral Ti(IV) and tetrahedral phosphate sites. Potassium has a high coordination number. All heavy atoms (Ti, P, K) are linked exclusively by oxides, which interconnect these atoms. Operational aspects Crystals of KTP are highly transparent for wavelengths between 350 and 2700 nm with a reduced transmission out to 4500 nm where the crystal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inorganic Compound
An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bondsthat is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''. Inorganic compounds comprise most of the Earth's crust, although the compositions of the deep Mantle (geology), mantle remain active areas of investigation. All allotropes (structurally different pure forms of an element) and some simple carbon compounds are often considered inorganic. Examples include the allotropes of carbon (graphite, diamond, buckminsterfullerene, graphene, etc.), carbon monoxide , carbon dioxide , carbides, and salt (chemistry), salts of inorganic anions such as carbonates, cyanides, cyanates, thiocyanates, isothiocyanates, etc. Many of these are normal parts of mostly organic systems, including organisms; describing a chemical as inorganic does not necessarily mean that it cannot occur within life, living things. History ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photochromic
Photochromism is the reversible change of color upon exposure to light. It is a transformation of a chemical species (photoswitch) between two forms through the absorption of electromagnetic radiation (photoisomerization), where each form has a different absorption spectrum. This reversible structural or geometric change in photochromic molecules affects their electronic configuration, molecular strain energy, and other properties. History In 1867, Carl Julius Fritzsche reported the concept of photochromism, indicating that orange tetracene solution lost its color in daylight but regained it in darkness. Later, similar behavior was observed by both Edmund ter Meer and Phipson. Ter Meer documented the color change of the potassium salt of dinitroethane, which appeared red in daylight and yellow in the dark. Phipson also recorded that a painted gatepost appeared black during the day and white at night due to a zinc pigment, likely lithopone. In 1899, Willy Marckwald, Willy Markwald, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Domain
A magnetic domain is a region within a magnetic material in which the magnetization is in a uniform direction. This means that the individual magnetic moments of the atoms are aligned with one another and they point in the same direction. When cooled below a temperature called the Curie temperature, the magnetization of a piece of ferromagnetic material spontaneously divides into many small regions called magnetic domains. The magnetization within each domain points in a uniform direction, but the magnetization of different domains may point in different directions. Magnetic domain structure is responsible for the magnetic behavior of ferromagnetic materials like iron, nickel, cobalt and their alloys, and ferrimagnetic materials like Ferrite (magnet), ferrite. This includes the formation of permanent magnets and the attraction of ferromagnetic materials to a magnetic field. The regions separating magnetic domains are called Domain wall (magnetism), domain walls, where the mag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferroelectric
In physics and materials science, ferroelectricity is a characteristic of certain materials that have a spontaneous electric polarization that can be reversed by the application of an external electric field. All ferroelectrics are also piezoelectric and pyroelectric, with the additional property that their natural electrical polarization is reversible. The term is used in analogy to ferromagnetism, in which a material exhibits a permanent magnetic moment. Ferromagnetism was already known when ferroelectricity was discovered in 1920 in Rochelle salt by American physicist Joseph Valasek.See and Thus, the prefix ''ferro'', meaning iron, was used to describe the property despite the fact that most ferroelectric materials do not contain iron. Materials that are both ferroelectric ''and'' ferromagnetic are known as multiferroics. Polarization When most materials are electrically polarized, the polarization induced, ''P'', is almost exactly proportional to the applied extern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Periodic Poling
Periodic poling is a formation of layers with alternate orientation in a birefringent material. The domains are regularly spaced, with period in a multiple of the desired wavelength of operation. The structure is designed to achieve quasi-phase-matching (QPM) in the material. Periodically poled crystals are frequently used as nonlinear optical materials. They are more efficient at second-harmonic generation than crystals of the same material without periodic structure. The material for the crystals is usually a wide-bandgap inorganic crystal, or in some cases a suitable organic polymer. Some popular materials in current use are potassium titanyl phosphate (KTP), lithium niobate, and lithium tantalate. The periodic structure is created in the crystal using a range of techniques. Pulsed electric field, electron bombardment, thermal pulsing, or other methods can be used to reposition the atom Atoms are the basic particles of the chemical elements. An atom consists of a atomic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quasi-phase-matching
Quasi-phase-matching is a technique in nonlinear optics which allows a positive net flow of energy from the pump frequency to the signal and idler frequencies by creating a periodic structure in the nonlinear medium. Momentum is conserved, as is necessary for phase-matching, through an additional momentum contribution corresponding to the wavevector of the periodic structure. Consequently, in principle any three-wave mixing process that satisfies energy conservation can be phase-matched. For example, all the optical frequencies involved can be collinear, can have the same polarization, and travel through the medium in arbitrary directions. This allows one to use the largest nonlinear coefficient of the material in the nonlinear interaction. Quasi-phase-matching ensures that there is positive energy flow from the pump frequency to signal and idler frequencies even though all the frequencies involved are not phase locked with each other. Energy will always flow from pump to signal as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sum-frequency Generation
Sum-frequency generation (SFG) is a second order nonlinear optical process based on the mixing of two input photons at frequencies \omega_1 and \omega_2 to generate a third photon at frequency \omega_3. As with any \chi^ optical phenomenon in nonlinear optics, this can only occur under conditions where: the light is interacting with matter, that lacks centrosymmetry (for example, surfaces and interfaces); the light has a very high intensity (typically from a pulsed laser). Sum-frequency generation is a "parametric process", meaning that the photons satisfy energy conservation, leaving the matter unchanged: :\hbar\omega_3 = \hbar\omega_1 + \hbar\omega_2 Second-harmonic generation A special case of sum-frequency generation is second-harmonic generation, in which \omega_1=\omega_2. In fact, in experimental physics, this is the most common type of sum-frequency generation. This is because in second-harmonic generation, only one input light beam is required, but if \omega_1\neq\omega ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nonlinear Optic
Nonlinear optics (NLO) is the branch of optics that describes the behaviour of light in nonlinear media, that is, media in which the polarization density P responds non-linearly to the electric field E of the light. The non-linearity is typically observed only at very high light intensities (when the electric field of the light is >108 V/m and thus comparable to the atomic electric field of ~1011 V/m) such as those provided by lasers. Above the Schwinger limit, the vacuum itself is expected to become nonlinear. In nonlinear optics, the superposition principle no longer holds. History The first nonlinear optical effect to be predicted was two-photon absorption, by Maria Goeppert Mayer for her PhD in 1931, but it remained an unexplored theoretical curiosity until 1961 and the almost simultaneous observation of two-photon absorption at Bell Labs and the discovery of second-harmonic generation by Peter Franken ''et al.'' at University of Michigan, both shortly after the constructio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Directional Coupler
Power dividers (also power splitters and, when used in reverse, power combiners) and directional couplers are passive devices used mostly in the field of radio technology. They couple a defined amount of the electromagnetic power in a transmission line to a port enabling the signal to be used in another circuit. An essential feature of directional couplers is that they only couple power flowing in one direction. Power entering the output port is coupled to the isolated port but not to the coupled port. A directional coupler designed to split power equally between two ports is called a hybrid coupler. Directional couplers are most frequently constructed from two coupled transmission lines set close enough together such that energy passing through one is coupled to the other. This technique is favoured at the microwave frequencies where transmission line designs are commonly used to implement many circuit elements. However, lumped component devices are also possible at lower ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Waveguide
A waveguide is a structure that guides waves by restricting the transmission of energy to one direction. Common types of waveguides include acoustic waveguides which direct sound, optical waveguides which direct light, and radio-frequency waveguides which direct electromagnetic waves other than light like radio waves. Without the physical constraint of a waveguide, waves would expand into three-dimensional space and their intensities would decrease according to the inverse square law. There are different types of waveguides for different types of waves. The original and most common meaning is a hollow conductive metal pipe used to carry high frequency radio waves, particularly microwaves. Dielectric waveguides are used at higher radio frequencies, and transparent dielectric waveguides and optical fibers serve as waveguides for light. In acoustics, air ducts and horns are used as waveguides for sound in musical instruments and loudspeakers, and specially-shaped metal rod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electro-optic Modulator
An electro-optic modulator (EOM) is an optical device in which a signal-controlled element exhibiting an electro-optic effect is used to modulate a Light beam, beam of light. The modulation may be imposed on the phase (waves), phase, frequency, amplitude, or Polarization (waves), polarization of the beam. Modulation bandwidths extending into the gigahertz range are possible with the use of laser-controlled modulators. The electro-optic effect describes two phenomena, the change of absorption and the change in the refractive index of a material, resulting from the application of a DC or an electric field with much lower frequency than the optical carrier. This is caused by forces that distort the position, orientation, or shape of the molecules constituting the material. Generally, a nonlinear optics, nonlinear optical material, such as ferroelectrics like lithium niobate (LiNbO3) or barium titanate (BaTiO3), polymers, or organic electro-optic materials, with an incident static or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laser Pointer
A laser pointer or laser pen is a (typically battery-powered) handheld device that uses a laser diode to emit a narrow low-power visible laser beam (i.e. Coherence (physics), coherent light) to highlight something of interest with a small bright colored spot. The small width of the beam and the low power of typical laser pointers make the beam itself invisible in a clean atmosphere, only showing a point of light when striking an opaque surface. Laser pointers can project a visible beam via scattering from dust particles or water droplets along the beam path. Higher-power and higher-frequency green or blue lasers may produce a beam visible even in clean air because of Rayleigh scattering from air molecules, especially when viewed in moderately-to-dimly lit conditions. The intensity of such scattering increases when these beams are viewed from angles near the beam axis. Such pointers, particularly in the green-light output range, are used as astronomical object pointers for teachi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
