Fiber optics Category Multiplexing de ArrayedWaveguideGrating he ...Arrayedwaveguide gratings AWG are commonly used as Optical add drop multiplexer optical de multiplexer s in wavelength division multiplexing wavelength division multiplexed WDM systems. These devices are capable of multiplexing a large number of wavelength s into a single optical fiber , thereby increasing the Transmission telecommunications transmission capacity of optical communication optical networks considerably. The devices are based on a fundamental principle of optics that light wave s of different wavelengths Interference wave propagation interfere linearly with each other. This means that, if each channel communications channel in an optical communication network makes use of light of a slightly different wavelength, then the light from a large number of these channels can be carried by a single optical fiber with negligible crosstalk electronics crosstalk between the channels. The AWGs are used to multiplex channels of several wavelengths onto a single optical fiber at the transmission end and are also used as demultiplexer s to retrieve individual channels of different wavelengths at the receiving end of an optical communication network. Operation of AWG devices Image ArrayedWaveguide Grating.svg center frame The incoming light 1 traverses a free space 2 and enters a bundle ... region 2 and 4 and the gratingwaveguide s 3 . The grating consists of a large number of waveguides ... 1 connected to the input port. Light diffraction diffracting out of the input waveguide at the coupler slab interface propagates through the free space region 2 and illuminates the grating with a normal distribution Gaussian distribution . Each wavelength of light coupled to the grating waveguides 3 , undergoes a constant change of phase waves phase attributed to the constant length increment in grating waveguides. Light diffracted from each waveguide of the grating Interference wave propagation ... more details
For the process of grating food Grater Image Curb gutter storm drain.JPG thumb 200px Curb road Curb , Street gutter gutter , and grating covering a storm drain A grating is any regularly spaced collection ... is usually perpendicular to the first as illustrated . ref http demonstrations.wolfram.com GratingGrating by S ndor Kabai, The Wolfram Demonstrations Project . ref When the two sets are perpendicular, this is also known as a mesh . Grating as bridge decks Grating can also come in convert 4 ft cm sigfig ... may also be available. Grating can be made of different materials like steel , Aluminium aluminum , fiberglass . Fiberglass grating is also known as FRP Grating . Gratings as filters Image Vindobona Hoher Markt 71.JPG thumb Grating drain cover , ancient Roman architecture at Vindobona , Austria . A grating ... . Diffraction gratings main Diffraction gratingGrating can also be a diffraction grating a reflection ... sawtooth gratings. The Y axis shows luminance the X axis shows space or distance. A grating can also be a picture having the characteristics of a grating. For example, a picture might be of a collection ... meter over the grating perpendicular to the Orientation geometry orientation of the grating. On the x ... wave grating see second panel of the illustration the graph consists of flat, low lines corresponding ... . One Periodic function period or wiktionary cycle cycle of such a grating consists of one black ... of the difference in luminance between the light parts of the grating and the dark parts. It is usually ... geometry Orientation is the angle the grating makes with some standard orientation such as the y axis in a picture . It is also usually measured in degree or in radians. Grating elements can have luminances other than that of sharp edged bars. If the graph of a grating is sinusoid al see top panel in the illustration , the grating looks like a set of blurry light and dark bars and it is called a sine wave grating. Sine wave gratings are used extensively in optics to determine the transfer function ... more details
dablink This page is about waveguides in the most general sense. For ordinary metal pipe waveguides, Waveguide electromagnetism . For optical waveguides, see Waveguide optics . File WaveguideJ Band.png thumb A section of flexible waveguide with a waveguide flange pressurizable flange File Waveguide x EM rect TE31.gif thumb right alt animation Electric field inside an x band hollow metal waveguide. A cross section of the waveguide allows a view of the field inside. Electric field inside an x band hollow metal waveguide. A waveguide is a structure which guides waves, such as electromagnetic wave ... . As a rule of thumb , the width of a waveguide needs to be of the same order of magnitude as the wavelength ... is the source power divided by R sup 2 sup . The waveguide confines the wave to propagation in one ... inside the waveguide due to total Reflection physics reflection from the waveguide wall, so that the propagation inside the waveguide can be described approximately as a zigzag between the walls ... thumb Waveguide supplying power for the Argonne National Laboratory Advanced Photon Source ... for long distances and with a high signal rate. In a microwave oven a waveguide transfers power from the magnetron where waves are formed, to the cooking chamber. In a radar, a waveguide transfers Radio ... for efficient power transmission see below . A waveguide called stripline can be created on a printed circuit board , and is used to transmit microwave signals on the board. This type of waveguide ... and objects. The waveguide can be put in contact with the specimen as in a Medical ultrasonography , in which case the waveguide ensures that the power of the testing wave is conserved, or the specimen may be put inside the waveguide as in a dielectric constant measurement ref J. R. Baker ... of the waveguide is described by the wave equation , which is derived from Maxwell s equations , and where the wavelength depends upon the structure of the waveguide, and the material within it air ... more details
be used to couple light into the waveguide, such as a grating coupler or prism coupler. One model ...dablink This page is about waveguides for transmission of optical signals or power. For other types of waveguide, see the disambiguation page Waveguide An optical waveguide is a physical structure that guides ... slab waveguide Image slab waveguide 1.svg thumb right 400px A dielectric slab waveguide consists ... waveguides are most easily understood as variants of the simple dielectric slab waveguide ref RWvD1984 , also called planar waveguide ref Silicon Photonics , by Graham T. Reed, Andrew P. Knights ref . The slab waveguide consists of three layers of materials with different dielectric constants, extending ... the depth of the layer, the slab waveguide model will be an excellent approximation. Guided modes of a slab waveguide can not be excited by light incident from the top or bottom interfaces. Light must ... in other devices. Two dimensional waveguides Strip waveguides A strip waveguide is basically a strip of the guiding layer confined between cladding layers. The simplest case is a rectangular waveguide , which is formed when the guiding layer of the slab waveguide is restricted in both transverse ... . The field distribution in rectangular waveguide cannot be solved analytically, however approximate solution methods, such as Marcatili s method , are known. Rib waveguides A rib waveguide is a waveguide .... main Optical fiber Optical fiber is typically a circular cross section dielectric waveguide consisting ... also ARROW waveguide Cutoff wavelength Dielectric constant Digital planar holography Electromagnetic radiation Erbium doped waveguide amplifier Equilibrium mode distribution Leaky mode Lightguide display Transmission medium WaveguideWaveguide electromagnetism Photonic crystal fiber Photonic crystal Prism coupler Zero mode waveguide Notes Note RWvD984 Ramo, Simon, John R. Whinnery, and Theodore ... titanyl phosphate KTP DEFAULTSORT Waveguide Optics Category Optics de Lichtleiter pl wiat ow d ... more details
diffraction grating. In optics , a diffraction grating is an optical component with a periodic .... The directions of these beams depend on the spacing of the grating and the wavelength of the light so that the grating acts as the dispersion optics dispersive element. Because of this, gratings ... pattern of purple lines forms a complex grating. For practical applications, gratings generally ... made diffraction grating was made around 1785 in science 1785 by Philadelphia inventor David Rittenhouse ... Joseph von Fraunhofer s wire diffraction grating in 1821 in science 1821 . Diffraction creates the Rainbow colors reflected from a Compact Disc see Examples, below . A grating has parallel lines ... plastic films based on reflective grating patches are very inexpensive to produce, and very commonplace. Theory of operation main Diffraction Image Difraction grating reflecting green light.JPG thumb 300px A diffraction grating reflecting only the green portion of the spectrum from a room s fluorescent lighting. The relationship between the grating spacing and the angles of the incident and diffracted beams of light is known as the grating equation . According to the Huygens Fresnel principle ... to a mirror or lens respectively. A grating has a zero order mode where m 0 , in which there is no diffraction ... as with a mirror or lens respectively. An idealised grating is considered here which is made up of a set .... When a plane wave of wavelength with Normal geometry normal incidence, perpendicular to the grating, each slit in the grating acts as a quasi point source from which light propagates in all directions although this is typically limited to a hemisphere . After light interacts with the grating ... emanating from each slit in the grating. At any given point in space through which diffracted light may pass, the path length to each slit in the grating will vary. Since the path length varies ... sub m sub m where sub m sub is the angle between the diffracted ray and the grating s Normal ... more details
Fiberglass reinforced plastic FRP grating is manufactured by combining a matrix of resin and fiberglass . That makes it a composite material . Fiberglass grating does not corrode like steel gratings. That is what gives them their value. They are used in corrosive environments. They lower maintenance costs. Types Molded Grating is made on a mold. Pultruded Grating made by joining pultruded profiles into the shape of a grating. Resins Many resin types may be used in pultrusion including polyester , polyurethane , vinylester epoxy , & isopthalic polyester Category Building materials Ref www.aagrating.com ... more details
Deleted image removed Image blazeangle.gif thumbnail 200px The blaze angle is the angular distance from the normal of the blaze groove and the normal of the diffraction grating. A blazed grating is a special type of diffraction grating . Blazed gratings produce maximum efficiency at a specified wavelength that is, a diffraction grating that is blazed at 250nm will operate most efficiently when light with a wavelength of 250 nm passes through the grating. Like standard diffraction gratings, blazed gratings diffract incoming light using a series of grooves. However, in blazed gratings the grooves have been manufactured such that they form right angles with a specified blaze angle, which is the angular distance from the surface normal of the diffraction plate. The magnitude of the blaze angle determines the wavelength at which the grating will be most efficient. Blazed gratings are useful in planet finding astronomy, and are used on the successful HARPS echelle grating echelle spectrograph . References Palmer, Christopher, Diffraction Grating Handbook , 6th edition, Newport Corporation 2005 . http gratings.newport.com library handbook cover.asp Category Optical devices Category Article Feedback 5 de Blazegitter fr R seau chelette ... more details
A holographic grating is a type of diffraction grating formed by an interference fringe field of two laser beams whose standing wave pattern is exposed to a polished substrate coated with photoresist. Processing of the exposed medium results in a pattern of straight lines with a Sine wave sinusoidal cross section. Holographic gratings may exhibit less scattered light than ruled gratings. Due to their sinusoidal groove profile, holographic gratings cannot be easily blazed and their efficiency is usually considerably less than a comparable ruled grating. However, an exception exists when the ratio of the period to the wavelength is near one in this case, a holographic grating has virtually the same efficiency as the ruled version. Holographic master gratings are Replicated optic replicated by a process identical to that used for ruled gratings. References Palmer, Christopher, Diffraction Grating Handbook , 6th edition, Newport Corporation 2005 http gratings.newport.com information handbook chapter4.asp Category Optical devices Category Photonics Category Optics Unreferenced date May 2007 ... more details
Infobox saint name Saint John of the Grating birth date 1098 death date 1168 feast day 1 February venerated in Roman Catholic Church image imagesize 250px caption birth place Brittany , France death place titles Bishop of Aleth beatified date beatified place beatified by canonized date 1517 canonized place canonized by Cultus confirmed by Pope Leo X attributes patronage major shrine suppressed date issues John of the Grating was a Cistercian Bishop of Aleth . John was born in Brittany , in 1098 he joined Clairvaux Abbey Clairvaux , ref http www.saintpatrickdc.org ss 0201.shtml Saint of the Day, February 1 John of the Grating SaintPatrickDC.org . Retrieved 2012 03 07. ref where he was professed by Bernard of Clairvaux St. Bernard . He would go on to found Sainte Croix de Guingamp and Saint Jacques de Montfort Abbeys, after his appointment as Bishop in 1144. ref http saints.sqpn.com saintj4n.htm Blessed John of the Grating Patron Saint Index ref He was given the moniker of Grating , due to the grating , or metal rails, surrounding his shrine. ref http www.catholic.org saints saint.php?saint id 4001 St. John of the Grating Catholic Online ref References Reflist Persondata Metadata see Wikipedia Persondata . NAME John of the Grating ALTERNATIVE NAMES SHORT DESCRIPTION DATE OF BIRTH 1098 PLACE OF BIRTH Brittany , France DATE OF DEATH 1168 PLACE OF DEATH DEFAULTSORT John of the Grating Category Roman Catholic saints Category 12th century Christian saints Category 1168 deaths Category 1098 births Category 12th century bishops Category Cistercians es Juan de Saint Malo fr Jean de la Grille ... more details
acts as a diffraction grating . Such a grating is known as an acoustical grating . Here, the antinode ... diffraction grating. This is obvious because the antinodes have points of minimum density and hence ... slits. Mathematics The grating element is equal to the wavelength of the ultrasonic waves. Let it be denoted by math d math . If math lambda math is the wavelength of the light passed through the grating ... grating. This method utilises the concept of Piezo electricity to obtain ultrasonic grating. The phenomenon of Diffraction of light using ultrasonic grating was first observed by Debye and Sears ... through the liquid at right angles to the waves, the liquid behaves as diffraction grating. Hence such a grating is called acoustic grating. This acoustical grating behaves in the same way as that of a normal ruled grating. Hence these can be used to determine the wavelength of monochromatic light as well .... Here, we need not worry about the grating element since the nodes themselves act as slits ... more details
An echelle grating from French, chelle , meaning stairs or ladder is a type of diffraction grating which is characterised by a relatively low groove density but is optimized for high diffraction order s. Echelle gratings are, like other types of diffraction grating, used in spectrometer s and similar instruments, such as High Accuracy Radial Velocity Planet Searcher HARPS , and numerous other astronomical instruments. Image Echelle Principle.svg thumb right 300px Echelle Spectrometer The first standard grating is optimized for a single lower order, while multiple higher orders of the echelle have an optimized output intensity. Both diffractive elements are mounted orthogonally in such a way that the highly illuminated orders of the echelle are transversally separated. Since only parts of the full spectrum of each individual order lie in the illuminated region, only portions of the different orders overlap spectrally i.e. green line in red portion . Principle As with other diffraction gratings, the echelle grating essentially consists of a number of slits with widths close to the wavelength of the diffracted light. Therefore light of a single wavelength in a standard grating at normal incidence is diffracted to the central zero order and successive higher orders at specific angles, defined by the grating density wavelength ratio and the selected order. The angular spacing between higher orders monotonically decreases and higher orders can get very close to each other, while lower ones are well separated. The intensity of the diffraction pattern can be altered by tilting the grating ... , the reflective portion can be Blazed grating tilted blazed to scatter a majority of the light ... element grating or prism optics prism is inserted as an order separator or cross disperser ... measurement times and improves efficiency. See also Diffraction grating References http gratings.newport.com ... title Diffraction Grating Handbook, 6th Edition year 2005 publisher Newport Corporation location ... more details
File Waveguide post filter.JPG thumb right Waveguide post filter a bandpass filter consisting of a length of WG15 divided into a row of five coupled oscillation coupled microwave cavity resonant cavities by fences of three posts each. The ends of the posts can be seen protruding through the wall of the guide. Each cavity has a tuning screw which adjusts its resonant frequency by varying the capacitance between the broad walls of the guide. The screws are secured with jam nut s and thread locking compound . A waveguide filter is an electronic filter that is composed of waveguide components. See also Distributed element filter Waffle iron filter Bibliography Hunter, I. C., Theory and Design of Microwave Filters , pp. 201 269, London Institution of Engineering and Tecnology, 2001 ISBN 0 85296 777 2. Category Microwave technology Category Signal processing filter electronics stub ... more details
Image SlottedWaveguideAntDet.jpg thumb right 250px The slotted waveguide antenna used by radar for traffic observation see highlighted area . The radio frequency circuits and antenna drive are contained in the housing below the antenna. A slotted waveguide is a waveguide that is used as an Antenna electronics antenna in microwave radar applications. Prior to its use in surface search radar, such systems used a parabola parabolic segment reflector. For comparison, in the parabolic type of antenna a feedhorn at the end of a waveguide directs a Cone geometry conical beam of output energy toward the reflector, whence it is focused into a narrow collimated beam . Reflected energy from the environment follows the reverse path and is focused by the reflector onto the feed horn where it travels back to the receiver. The reflector must be built to a precision determined by the wavelength used. For a one centimeter wavelength, a reflector precision of one or two millimeters would be adequate. Image Slottedwaveguide.jpg thumb left 150px Slotted waveguide for 2.4 GHz. A slotted waveguide has no reflector but emits directly through the slots. The spacing of the slots is critical and is a multiple of the wavelength used for transmission and reception. The effect of this geometry is to form a high gain antenna that is highly directional in the plane of the antenna. Without augmentation a slotted waveguide is not as efficient as a parabolic reflector, lacking an ability to focus in the vertical plane, but is much more durable and is less expensive to construct. The antenna s vertical focus is usually enhanced by the application of a microwave lens attached to the front of the antenna. As this, like the companion slotted waveguide, is a one dimensional device, it too may be made relatively cheaply as compared to a parabolic reflector and feedhorn. Usually a slotted waveguide antenna is protected ... Slotted Waveguide Antennas Antenna Theory.com Category Radar de Schlitzantenne eo Truita ... more details
frequencies. For optical waveguides, see Waveguide optics . For other types of waveguide, see Waveguide ... and communications system engineering communications engineering , the term waveguide may refer ... metal pipe used to carry radio wave s. This type of waveguide is used as a transmission line ..., satellite communications , and microwave radio links. A dielectric waveguide employs a solid dielectric ... frequencies. Transmission lines such as microstrip , coplanar waveguide, stripline or coaxial may also be considered to be waveguides. The electromagnetic waves in metal pipe waveguide may be imagined ... walls of the guide. For the particular case of rectangular waveguide , it is possible to base an exact analysis on this view. Propagation in dielectric waveguide may be viewed in the same way, with the waves ... radiative dielectric waveguide and the Goubau line , use both metal walls and dielectric surfaces ... with UBR120 flanges.svg thumb right 200px Short length of rectangular waveguide WG17 with waveguide ... WAVEGUIDE.JPG thumb right Section of flexible waveguide History The first waveguide was proposed by J ... the waveguide is. For example the natural waveguide the earth forms given by the dimensions ... frequency below which the mode cannot exist in the guide. Waveguide propagation modes depend on the operating ... mode of a waveguide is a particular standing wave pattern formed by waves confined in the cavity ... modes respectively. gallery Image TE10.svg TE sub 1,0 sub mode of a rectangular hollow metallic waveguide. Image TE11.svg TE sub 1,1 sub mode of a circular hollow metallic waveguide. gallery Hollow metallic waveguides File Waveguide.svg thumb Rectangular hollow Waveguide File WaveguideJ Band.png thumb right 200px Flexible waveguide from a J Band radar In the microwave region of the electromagnetic spectrum , a waveguide normally consists of a hollow metallic conductor. These waveguides can take ... to be evacuated as part of evacuated systems. e.g. electron beam systems A slotted waveguide is generally ... more details
Image Waveguide flange UBR320.jpg thumb right 240px Figure 1. A UBR320 flange on R320 WG22, WR28 guide ... by the distinct colours of the copper waveguide tube and brass flange. A waveguide flange is a connector for joining sections of waveguide electromagnetism waveguide , and is essentially the same as a pipe flange a waveguide , in the context of this article, being a hollow metal conduit for microwave ..., particularly for very small waveguides. Key features of a waveguide join are whether or not it is air tight, allowing the waveguide to be pressurized, and whether it is a contact or a choke connection. This leads to three sorts of flange for each size of rectangular waveguide. For rectangular ... and circular waveguides. Pressurization The atmosphere within waveguide assemblies is often pressurized ... and hence increase the power that it can carry. Pressurization requires that all joins in the waveguide ... is then not pressurizable. Electrical continuity Image Waveguide choke flange UG 1666 ... flange right . These flanges are aluminium and are socket mounted onto aluminium WG18 WR62 waveguide ... flanges, and ideally creates a continuous inner surface from one waveguide to the other, with no crack ... it. Choke connection Image Waveguide choke flange cross section.svg thumb left Figure 3. E plane cross section of connected choke and gasket cover waveguide flanges from figure 2. The gap ... br a. waveguide tubing socket mounted into... br b. choke flange and... br c. gasket cover flange ... are only used with rectangular waveguide, and are invariably pressurizable, having a gasket groove ... of the broad walls of the waveguide along its centre line, which is where the longitudinal surface ... branch is designed to present a low input impedance where it meets the broad walls of the waveguide ..., and minimizes the current across it. The distance from the main waveguide through the gap ... of the ditch to a low ideally zero impedance at the broad wall of the waveguide. File Protective ... more details
Unreferenced date December 2008 An atmospheric waveguide is an Earth s atmosphere atmospheric Fluid dynamics flow feature that improves the propagation of certain atmospheric wave s. The effect arises because wave parameters such as group velocity or vertical wavenumber depend on mean flow direction and strength. Thus, for instance, westerly wind westerlies might be a good waveguide for east ward traveling waves, but might strongly dissipation dissipate west ward traveling waves, by increasing or decreasing their vertical wavenumber, respectively. Modification of the waves group velocity will change their meridional propagation speed, directing them more geographical pole polewards or more equator wards. Category Atmosphere ... more details
In optics , an anti resonant reflecting optical waveguide ARROW is formed from an anti resonant Fabry P rot reflector. The optical mode is leaky, but relatively low loss propagation can be achieved by making the Fabry P rot reflector of sufficiently high quality or small size. ARROWs can be realized as cylindrical waveguides 2D confinement or slab waveguides 1D confinement . The latter ARROWs are practically formed by a low index layer, embedded between higher index layers. Note that the refractive indices of are reversed, when comparing to usual waveguides. Light is confined by total internal reflection TIR on the inside of the higher index layers, but achieves a lot of modal overlap with the lower index central volume. This strong overlap can be made plausible in a simplified picture imagining rays , as in geometrical optics . Such rays are refracted into a very shallow angle, when entering the low index inner layer. Thus, one can use the metaphor that these rays stay very long inside the low index inner layer. Note this is just a metaphor and the explanatory power of ray optics is very limited for the micrometer scales, at which these ARROWs are typically made. ARROW structures are often used for guiding light in liquids, particularly in microfluidic systems. This is due to the difficulty of finding suitable optical cladding materials, with a lower refractive index than the liquid, which would be required to form a conventional waveguide structure. See also http cleanroom.byu.edu ARROWcalc.phtml Integrated Hollow ARROWs Waveguide optics Category Optical devices optics stub ... more details
A slot waveguide is an optical waveguide that guides strongly confined light in a sub wavelength scale low refractive index region by total internal reflection . A slot waveguide consists of two strips .... Image picSlot2D.jpg right thumb 200px Schematic 2D slot waveguide. Light propagates in the z direction Image picSlot3D.jpg right thumb 200px Schematic 3D slot waveguide. Light propagates in the z direction Principle of operation The principle of operation of a slot waveguide is based on the discontinuity ... H sub sup N sup . Image field2D.jpg right thumb 200px E field profile of a 2D slot waveguide. E vector is parallel to the y axis Image field3D.jpg right thumb 200px E field distribution of a 3D slot waveguide ... The slot waveguide was born in 2003 as an unexpected outcome of theoretical studies on metal oxide ..., no. 14, pp. 1626 1628, 2004. ref of the first slot waveguide implemented in the Si SiO sub 2 sub ... these pioneering works, several guided wave configurations based on the slot waveguide concept have ... multi slot waveguide in order to increase the optical field in the low refractive index regions ... slot waveguide in a horizontal configuration was first published in 2007 ref R. Sun, P. Dong, N ... waveguide approach was extended to the terahertz frequency band by researchers at RWTH Aachen University ... that a slot waveguide, in combination with nonlinear electrooptic polymers , could be used ..., Nonlinear polymer clad silicon slot waveguide modulator with a half wave voltage of 0.25 V, Applied Physics Letters 92, 163303 2008 . ref In 2007, a non planar implementation of the slot waveguide ... of a non planar fiber based slot waveguide configuration has also been demonstrated by means of conventional microstructured optical fiber technology ref name fiber2007 . Applications A slot waveguide ..., Electrically driven silicon resonant light emitting device based on slot waveguide, Optics. Express .... As firstly pointed out in ref name first , the slot waveguide can be used to greatly increase the sensitivity ... more details
This page is about waveguides for acoustics and sound, for other types of waveguide, see Waveguide Unreferenced date December 2006 An acoustic waveguide is a physical structure for guiding sound wave s. Examples One example might be a speaking tube used aboard ships for communication between decks. Other examples include the rear passage in a transmission line loudspeaker enclosure, the ear canal or a device like a stethoscope . The term also applies to guided waves in solids. A duct for sound propagation also behaves like a transmission line e.g. air conditioning duct, car muffler, etc. . The duct contains some Transmission medium medium , such as air , that supports sound propagation. Its length is typically around quarter of the wavelength which is intended to be guided, but the dimensions of its cross section geometry cross section are smaller than this. Sound is introduced at one end of the tube by forcing the pressure to vary in the direction of propagation, which causes a pressure gradient to travel perpendicular to the cross section at the speed of sound . When the wave reaches the end of the transmission line, its behaviour depends on what is present at the end of the line. There are three generalized scenarios A low Acoustic impedance impedance load e.g. leaving the end open in free air will cause a reflected wave in which the sign of the pressure variation reverses, but the direction of the pressure wave remains the same. A load that matches the characteristic impedance defined below will completely absorb the wave and the energy associated with it. No Reflection physics reflection will occur. A high impedance load e.g. by plugging the end of the line will cause a reflected wave in which the direction of the pressure wave is reversed but the sign of the pressure remains the same. Since a transmission line behaves like a four terminal model, one cannot really define or measure the impedance of a transmission line component. One can however measure its input ... more details
Unreferenced auto yes date December 2009 Tandemly arrayed genes are a gene cluster created by tandem duplication s. They serve to encode large numbers of genes at a time. An example are tandem clusters of rRNA encoding genes. These genes are translated faster than they would be if only a single copy of the gene was available. See also Gene cluster Satellite DNA Tandem repeats DEFAULTSORT Tandemly Arrayed Genes Genetics stub Category Genetics ... more details
Orphan date February 2009 A waveguide rotary joint is used in microwave communications to connect two different types of Radio frequency RF waveguides. Because coaxial parts are symmetrical in direction, free rotation without performance degradation is accomplished. In the rotating part, electrical continuity is achieved by 4 chokes eliminating metal contacts. The Rotary Joints can have both waveguide ports at a right angle to the rotational axis, U style , one waveguide port at a right angle and one in line, L style or both waveguide ports in line. I style . Waveguide Rotary Joint modules are available for all frequency band s. ref http www.ecplaza.net tradeleads seller 4818912 waveguide rotary joints.html www.ecplaza.net WAVEGUIDE ROTARY JOINTS ref References reflist Category Radio terminology ... more details
The Earth ionosphere waveguide refers to the phenomenon in which certain Radio propagation radio waves can propagate in the space between the ground and the boundary of the ionosphere . Because the ionosphere contains charged particles , it can behave as a Electrical conductor conductor . The earth operates as a ground plane , and the resulting cavity behaves as a large waveguide . Extremely low frequency ELF and Very low frequency VLF 300 Hertz Hz 30 kHz frequency signals can propagate efficiently in this waveguide. For instance, lightning strikes launch a signal called radio atmospherics , which can travel many thousands of miles, because they are confined between the Earth and ionosphere. The round the world nature of the waveguide produces resonance s, like a cavity, which are at 7 Hz. See also Radio propagation Skywave Shortwave radio Tropospheric ducting Atmospheric duct Waveguide radio spectrum DEFAULTSORT Earth Ionosphere Waveguide Category Electromagnetism Category Radio technology Category Radio frequency propagation Telecomm stub physics stub ... more details
Electromagnetically induced grating EIG is an optical Interference wave propagation interference phenomenon where an interference pattern is used to build a dynamic spatial diffraction grating in matter. EIGs are dynamically created by light interference on optically resonant materials and rely on population inversion and or optical coherence physics coherence properties of the material. They were first demonstrated with population gratings on atoms. ref Mitsunaga et al., Phys. Rev. A 59, 4773 1999 ref EIGs can be used for purposes of atomic molecular velocimetry, ref cite journal doi 10.1016 S0030 4018 99 00228 X title Transient Bragg diffraction by a transferred population grating application for cold atoms velocimetry year 1999 author Tabosa, J journal Optics Communications volume 165 pages 59 ref to probe the material optical properties such as coherence and population life times, ref G.C.Cardoso, Phys. Rev. A 65, 033803 B 2002 . ref and switching and routing of light. ref Brown AW, Xiao, M, Opt. Lett. 30, 699 2005 Su XM, Ham BS, Dynamic control of the photonic band gap using quantum ... of the grating is controlled by the angle math theta math . The writing and reading frequencies ... is the signal obtained by diffraction on the grating. Image Write Read EIG color.jpg left thumb 260px ... conditions for EIG diffraction Types of EIG Image Grating types.jpg right thumb 300px Figure 3 Difference between a matter grating a population grating . The smiley s and represent ground and optically excited atoms, respectively. Matter Gratings The writing lasers form a grating by modulating ... interference fields. A thermal grating is an example. Matter gratings have slow dynamics milliseconds ... The writing lasers are resonant with optical transitions in the matter and the grating is formed by optical pumping . See Fig. 3 Coherence Gratings A grating where the writing lasers form a coherent ... transparency Bragg s law Notes reflist References Laser induced thermal grating effects in flames ... more details
A zero mode waveguide is an optical waveguide that guides light energy into a volume that is small in all dimensions compared to the wavelength of the light. Zero mode waveguides have been developed for rapid parallel sensing of zeptolitre sample volumes, as applied to gene sequencing , by Pacific Biosciences previously named Nanofluidics, Inc. ref Cite book title DNA sequencing optimizing the process and analysis author Jan Kieleczawa publisher Jones & Bartlett Publishers year 2004 isbn 978 0 7637 4782 4 page 190 url http books.google.com ?id 23NGy0VuVUEC&pg PA190&dq zero mode waveguide&q zero mode waveguide ref A waveguide operated at frequencies lower than its cutoff frequency wavelengths longer than its cutoff wavelength and used as a precision attenuator is also known as a waveguide below cutoff attenuator. ref Cite journal doi 10.1109 22.643852 author D. H. Russell journal IEEE Trans. Microwave Theory and Technology title The waveguide below cutoff attenuation standard url http ieeexplore.ieee.org xpl freeabs all.jsp?arnumber 643852 volume 45 issue 12 pages 2408 2413 date Dec. 1997 bibcode 1997ITMTT..45.2408R ref See also Single molecule real time sequencing References references Category Biophysics Category Optics optics stub genetics stub ... more details
mergeto Optical amplifier discuss Talk Optical amplifier Merger proposal date August 2009 An erbium doped waveguide amplifier EDWA is an optical amplifier that uses a waveguide to boost an optical signal, analogous to an erbium doped fiber amplifier EDFA . External links http www.pcmag.com encyclopedia term 0,2542,t EDWA&i 42398,00.asp Definition at PCmag Optics stub Category Amplifiers Category Photonics ... more details
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