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公开(公告)号：US5617239A
公开(公告)日：1997-04-01
申请号：US360829
申请日：1995-01-17
Applicant: Nigel G. Walker
Inventor： Nigel G. Walker
CPC classification number: H04B10/25751 , H04B2210/006
Abstract: An optical source for a communications system includes an optical signal source whose output is modulated to contain sidebands. The sidebands interact to produce beat frequencies and modifying apparatus, such as a length of dispersive optical fibre, is used to modify characteristics of the sidebands so that the beat frequency can be detected at a receiver such as a photodetector. In this way, high frequency signals can be generated and photodetected, the output of the receiver being suitable to drive a microwave antenna, thus providing an optically fed microwave communications link. Using a video signal generator a video signal can be superimposed on the received beat frequency and therefore carried by the microwave link.
Abstract translation: PCT No.PCT / GB93 / 01353 Sec。 371日期1995年1月17日 102（e）日期1995年1月17日PCT Filed 1993年6月29日PCT公布。 出版物WO94 / 0092800 日期1994年1月6日通信系统的光源包括一个光信号源，其信号被调制成包含边带。 边带相互作用以产生节拍频率，并且修改装置，例如一长度的色散光纤，用于修改边带的特性，从而可以在诸如光电检测器的接收机处检测拍频。 以这种方式，可以产生和检测高频信号，接收器的输出适于驱动微波天线，从而提供光馈的微波通信链路。 使用视频信号发生器，可以将视频信号叠加在所接收的节拍频率上，由此由微波链路携带。
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公开(公告)号：US4988169A
公开(公告)日：1991-01-29
申请号：US201122
申请日：1988-05-20
Applicant: Nigel G. Walker
Inventor： Nigel G. Walker
CPC classification number: G02F1/0136 , G02F1/0121 , G02F1/035 , G02F2001/0142 , G02F2203/07 , Y10S359/90
Abstract: A method and apparatus for controlling the polarization of an optical signal has many applications, including in coherent systems, e.g. heterodyne detectors. Four birefringent elements (19, 21, 23, 25) in series are arranged to rotate the state of polarization (SOP) alternately about orthogonal axes on a Poincare sphere. A controller enables time varying initial and final polarization states (S, S') to be tracked. It also ensures that the birefringence limits of the elements are never reached by carrying out an adjustment procedure. A reduction by a full revolution (2.pi.) for one element (e.g. 19) can be achieved by varying the transformations of the other elements by not more than .pi..
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公开(公告)号：US4958918A
公开(公告)日：1990-09-25
申请号：US294069
申请日：1989-01-03
Applicant: Nigel G. Walker
Inventor： Nigel G. Walker
CPC classification number: G02F1/035 , G02F1/0136 , G02F2201/066
Abstract: Apparatus for processing one or more optical signals to produce a desired polarization transformation on a Poincare sphere has particular application in a receiver for a coherent communication system. One or more birefringent elements (11) receive a polarized optical signal from a local oscillator (12), and vary the state of polarization of the local optical signal in order to match it to a received optical signal from a remote source on a line (13). The transformed local signal is fed on a line (14) to a directional coupler (15) which compares the local and remote optical signals. A receiver (16) extracts data by interference between the two signals in the directional coupler (15), and feeds data out at a line (17). A level detector (18) detects the level of the output signal (17) and supplies a feed-back signal to a polarization controller (19), which controls the birefringent element or elements (11). The birefringent device (11) is adapted to provide a variable rotation on a Poincare sphere about an axis of rotation which itself may be varied in direction. The control means (19) varies the amount of rotation on the Poincare sphere produced by the birefringent device, and varies the direction of the axis about which the rotation takes place, so as to achieve the desired polarization transformation. A preferred form of the birefringent device (11) comprises a waveguide (20) of electro-optic material, and means (22, 23) for producing in the electro-optic material an electric field or variable strength and variable orientation whereby required polarization transformation can take place. Preferably the electro-optic material is lithium niobate.
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