1、 TIA-440-B (Revision of TIA-440-A) February 2004Fiber Optic Terminology ANSI/TIA-440-B-2004 APPROVED: FEBRUARY 20, 2004 REAFFIRMED: AUGUST 23, 2013 NOTICE TIA Engineering Standards and Publications are designed to serve the public interest through eliminating misunderstandings between manufacturers
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19、, AND THESE CONTENTS WOULD NOT BE PUBLISHED BY TIA WITHOUT SUCH LIMITATIONS. TIA-440-B - 1 -FIBER OPTIC TERMINOLOGY Forward (This Foreword is informative only and is not part of this standard.) From TIA Project No. 1384, formulated under the cognizance of TIA FO-4.5 Subcommittee on Fiber Optic Metro
20、logy. The initial base for this Standard was prepared jointly by the National Telecommunications and Information Administration, Institute for Telecommunication Sciences (NTIA/ITS) and the National Institute of Standards Technology (NIST). The EIA was granted permission by the Institute of Electrica
21、l and Electronic Engineers, Inc. (IEEE) and by NTIA/ITS to use and publish terms from their documents to update and revise EIA Recommended Standard RS-440, published May 1978. IEEE Standard 812-1984 includes many of the terms and definitions from the aforementioned base. It was a major source refere
22、nce for revision EIA/TIA-440-A. Selected terms from the U.S. Military document MIL-STD-2196 and U.S. Government document FED-STD-1037 were added for this revision as well as new terms formulated due to changing technology. 1 Scope The purpose of this Standard is to define commonly used terms, symbol
23、s and abbreviations for fiber optic applications. Terms are arranged in alphabetical order and definitions follow the listed term without repeating the term. If a term consists of two or more words, and its modifiers and the generic word form a single concept, the terms have been alphabetized with t
24、he modifier as the initial word. The meanings of some terms differ in the context in which they are used, thus requiring more than one definition. A definition appears with a preferred term. Variations are included in the alphabetical list with cross reference to the preferred term. The designation
25、See also: following a definition draws attention to related terms. 2 Terms and Definitions Absorption In an optical fiber, that portion of attenuation resulting from conversion of optical power into heat. NOTE: Intrinsic components consist of tails of ultraviolet and infrared absorption bands. Extri
26、nsic components include: (a) impurities, e.g., the OH - ion and transition metal ions, and (b) defects, e.g., results of thermal history and exposure to nuclear radiation. See also: Attenuation. TIA-440-B DWL, 05/09/02 - 2 -Acceptance Angle Half the vertex angle of that cone within which optical pow
27、er may be coupled into bound or leaky modes of a multi-mode fiber. NOTE: Acceptance angle is a function of position on the entrance face of the core when the refractive index is a function of radius in the core. Acceptance Pattern (Fiber Bundle or Fiber) A curve of total transmitted power plotted ag
28、ainst the launch angle. Access Coupler A device placed between two fiber ends to allow signals to be withdrawn from or entered into one of the fibers. See also: Optical Fiber Coupler. Acousto-Optic Effect A periodic variation of refractive index caused by an acoustic-wave. NOTE: The acousto-optic ef
29、fect is used in devices that modulate and deflect light. See also: Modulation. Acquisition Time In a device that puts out a signal as a result of an input signal, such as an optical transmitter or receiver, the time between the instant of application of the leading edge of an input signal and the st
30、abilization of the corresponding output signal. Should this include an equation? Active Branching Device Device which converts an optical input into two or more optical outputs with gain or regeneration. See also: Branching Device. Active Laser Medium The material within a laser, such as crystal, ga
31、s, glass, liquid or semiconductor, that emits coherent radiation (or exhibits gain) as the result of stimulated electronic or molecular transitions to lower energy states. Synonym: Laser Medium. See also: Laser; Optical Cavity. Active Star Coupler Device in which power from one or several input fibe
32、rs is distributed amongst a larger number of output optical fibers with gain or regeneration. See also: Optical Combiner; Star Coupler. Adapter The double female portion of a fiber optic connector assembly that joins two male connector plugs. Adaptive Optics The development and use of optical compon
33、ents whose characteristics are controlled during their operational use in order to modify the characteristics of lightwaves propagating within them. Controlled lightwave characteristics include wavefront direction, polarization, modal power distribution, electromagnetic field strength, or the path t
34、hey take. TIA-440-B - 3 -Adjustable Attenuator An optical attenuator in which the level of attenuation is varied with an internal adjustment through external control. Synonym: Variable Attenuator. Aligned Bundle A bundle of optical fibers in which the relative spatial coordinates of each fiber are t
35、he same at the two ends of the bundle. NOTE: The term “Coherent Bundle“ is often employed as a synonym, and should not be confused with phase coherence or spatial coherence. Synonym: Coherent Bundle. See also: Fiber Bundle. Alpha Profile See also: Power-Law Index Profile. Alternative Test Method (AT
36、M) A test method in which a given characteristic of a specified component or device is measured in a manner that is consistent with the definition of the characteristic, gives reproducible results that are relatable to the reference test method, and is relatable to practical use. Ambient Light Susce
37、ptibility The optical power that enters a device from ambient illumination incident upon the device. Angle of Deviation In optics, the net angular deflection experienced by a light ray after one or more refractions or reflections. NOTE: The term is generally used in reference to prisms, assuming air
38、 interfaces. The angle of deviation is then the angle between the incident ray and the emergent ray. See also: Reflection; Refraction. Angle of Incidence The angle between an incident ray and the normal to a reflecting or refracting surface. See also: Critical Angle; Total Internal Reflection. Angle
39、 of Reflection The angle formed between the normal to a surface and the reflected ray. The angle lies in a common plane with the angle of incidence and is equal to it. Angle of Refraction The angle formed between a refracted ray and the normal to the surface. TIA-440-B DWL, 05/09/02 - 4 -Angstrom A
40、unit of length in optical measurement. 1 = 10-10 meter. = 10-4micrometer. = 10-1nanometer. NOTE: The angstrom has been used historically in the field of optics, but it is not an SI (International System) unit. Angular Misalignment Loss The optical power loss caused by angular deviation from the opti
41、mum alignment of source to optical fiber, fiber to fiber, or fiber to detector. See also: Extrinsic Joint Loss; Gap Loss; Intrinsic Joint Loss; Lateral Offset Loss. Anisotropic Pertaining to a material whose electrical or optical properties are different for different directions of propagation or di
42、fferent polarizations of a traveling wave. See also: Isotropic. Antireflection Coating A thin, dielectric or metallic film (or several such films) applied to an optical surface to reduce the reflectance and thereby increase the transmittance. NOTE: The ideal value of the refractive index of a single
43、 layered film is the square root of the product of the refractive indices on either side of the film, the ideal optical thickness being one quarter of a wave-length. See also: Dichroic Filter; Fresnel Reflection; Reflectance; Transmittance. APD Abbreviation for Avalanche Photodiode. NOTE: apd and a.
44、p.d. are also used. TIA-440-B - 5 -Attenuation In an optical fiber, the diminution of average optical power. NOTE: In an optical fiber, attenuation results from absorption, scattering, and other radiation. Attenuation is generally expressed in dB. However, attenuation is often used as a synonym for
45、attenuation coefficient, expressed in dB/km. See also: Attenuation Coefficient; Coupling Loss; Differential Mode Attenuation; Equilibrium Mode Distribution; Extrinsic Joint Loss; Insertion Loss; Intrinsic Joint Loss; Leaky Mode; Macrobend Loss; Material Scattering; Microbend Loss. Attenuation Coeffi
46、cient The rate of diminution of average optical power with respect to distance along the fiber. Defined by the equation: =1010)0()(zPzPWhere P(z) is the power at distance z along the guide and P(0) is the power at z = 0; is the attenuation coefficient in dB/km if z is in km. From this equation, =)0(
47、)(log1010PzPz This assumes that is independent of z; if otherwise, the definition must be given in terms of incremental attenuation as: =zdzzPzP010)(10)0()(or, equivalently, =)0()(log10)(10PzPdzdz See also: Attenuation; Attenuation Constant; Axial Propagation Constant Attenuation Constant For a part
48、icular mode, the real part of the axial propagation constant. The attenuation coefficient for the mode power is twice the attenuation constant. See also: Attenuation Coefficient; Axial Propagation Constant; Propagation Constant. Attenuation-Limited Operation The condition prevailing when the receive
49、d signal amplitude (rather than distortion) limits performance. See also: Bandwidth-Limited Operation; Distortion-Limited Operation. TIA-440-B DWL, 05/09/02 - 6 -Avalanche Photodiode (APD) A photodiode designed to take advantage of avalanche multiplication of photocurrent. NOTE: As the reverse-bias voltage approaches the breakdown voltage, hole-electron pairs created by absorbed photons acquire sufficient energy to create additional hole-electron pairs when they collide with ions; thus a multiplication (signal gain) is achieved. See also: APD; Photodiode
