Coupling device for single mode optical fiber and communications system comprising same

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	Coupling device for single mode optical fiber and communications system comprising same
其他题名	Coupling device for single mode optical fiber and communications system comprising same
	ABERSON, JAMES ASHLEY, JR.; WHITE, IAN ARTHUR
	1987-05-13
专利权人	AT&T CORP.
公开日期	1987-05-13
授权国家	欧洲专利局
专利类型	发明申请
摘要	Optical radiation can be efficiently removed from, or injected into, single mode optical fiber at an intermediate point along the fiber, by causing quasi-resonant coupling of the guided mode LP01 to an appropriate tunneling leaky (TL) mode, e.g., LP1 Such coupling is caused by means of a "grating" in the fiber, with the grating being formed by impressing a periodic (or pseudo-periodic) modulation on the fiber, or by causing a periodic (or pseudo-periodic) variation of the refractive index of the fiber by means of the photoelastic or the photorefractive effect. The nominal grating spacing ^(z) is chosen such that Oo = (2π/) > β01-2πncl^o, where w is the average grating spacing, β01, is the propagation constant of the LP01 mode, ncl is the refractive index of the fiber cladding, and o is the wavelength of the radiation to be coupled from or into the fiber. Furthermore, ^(z) is to be chosen such that Oo β01, - βrs, where βrs is the propagation constant of the selected TL mode. In order for the coupling to be quasi-resonant, it is necessary that αrs, the attenuation constant of the selected TL mode, be relatively small, typically < 1 dB/cm. By appropriately choosing ^(z) and/or the amplitude function of the grating, it is possible to increase the coupling efficiency above what is possible with a constant spacing, constant amplitude grating. Devices according to the invention can be advantageously used not only as radiation couplers but also as filters and, if they are of the photorefractive type, as amplitude modulators.
其他摘要	通过使引导模式LP01的准谐振耦合到适当的隧道泄漏（TL）模式，例如LP11，可以在沿光纤的中间点处有效地从单模光纤中去除或注入光辐射。这种耦合是通过光纤中的“光栅”引起的，光栅是通过在光纤上施加周期性（或伪周期性）调制或通过引起折射的周期性（或伪周期性）变化而形成的。通过光弹性或光折变效应的纤维指数。选择标称光栅间距^（z），使得Oo =（2π/）>β01-2πncl^ o，其中w是平均光栅间距，β01，是LP01模式的传播常数，ncl是折射率光纤包层，o是从光纤耦合或进入光纤的辐射波长。此外，选择^（z）使得Ooβ01，-βrs，其中βrs是所选TL模式的传播常数。为了使耦合成为准谐振，所选TL模式的衰减常数αrs必须相对较小，通常<1dB / cm。通过适当地选择光栅的λ（z）和/或幅度函数，可以将耦合效率提高到高于恒定间隔恒定幅度光栅的可能性。根据本发明的装置不仅可以有利地用作辐射耦合器而且可以用作滤光器，并且如果它们是光折变型的，则可以用作振幅调制器。
主权项	Means for coupling electromagnetic radiation of wavelength λ o into or from an intermediate portion of an optical fiber, the fiber comprising a core and a cladding surrounding the core and having optical characteristics including an attenuation constant α ij and a propagation constant β ij for each mode LP ij of the radiation that can be present in the fiber, where i is a non-negative integer and 1 is a positive integer, CHARACTERIZED IN THAT a) the fiber is a single mode optical fiber at the wavelength λ o; b) the coupling means comprise means for forming in the intermediate portion of the fiber a "grating" consisting of N elements, a grating being a portion of fiber in which one or more fiber parameters are caused to vary as a function of the axial coordinate z of the fiber, the fiber parameters including the core refractive index and the fiber axis geometry, asscciated with the grating being a nominal repeat distance ∧(z) and a nominal amplitude function g(z); c) ∧(z) is chosen such that O o = (2π) > β 01 - 2πn cl∧ o, where is the average repeat spacing in the grating, β 01 is the propagation constant of the LP 01 mode of radiation, and n c1 is the refractive index of the cladding of the fiber; d) ∧(z) furthermore is chosen such that O o β 01 - β rs, where β rs is the propagation constant of the LP rs mode of radiation, where LP rs is a tunneling leaky (TL) mode of the radiation of wavelength λ o in the fiber; and e) the attenuation constant α rs of the LP rs mode is less than about 1 dB/cm.
申请日期	1986-11-06
专利号	EP0221560A2
专利状态	失效
申请号	EP1986115406
公开（公告）号	EP0221560A2
IPC 分类号	G02B6/293 \| G02B6/02 \| G02B6/14 \| G02B6/34 \| G02B6/42 \| G02F1/01 \| G02F1/05 \| H04B10/00 \| H04B10/12 \| H04B10/13 \| H04B10/135 \| H04B10/14 \| H04B10/20 \| H04B10/22 \| H04B9/00
专利代理人	-
代理机构	BLUMBACH WESER BERGEN KRAMER ZWIRNER HOFFMANN PATENTANWÄLTE
文献类型	专利
条目标识符	http://ir.opt.ac.cn/handle/181661/51824
专题	半导体激光器专利数据库
作者单位	AT&T CORP.
推荐引用方式 GB/T 7714	ABERSON, JAMES ASHLEY, JR.,WHITE, IAN ARTHUR. Coupling device for single mode optical fiber and communications system comprising same. EP0221560A2[P]. 1987-05-13.

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