Patent ID: 6788901
Filing Date: 2004-09-07
Classification: G02B,H01S,H04B

Abstract:
A method of forming and transmitting a modulated optical radiation beam for free-space optical communication, the method comprising:forming optical radiation modulated by an information signal, the modulated optical radiation having a frequency spectrum width &Dgr;v, wherein the information signal modulated on the radiation has a frequency bandwidth &dgr;v; applying the modulated optical radiation to an input of a multimode optical fiber in such a manner as to excite substantially all possible modes for the optical radiation supported by the multimode fiber; wherein the parameters of the optical radiation and of the multimode fiber are selected to satisfy the following expressions: L&CenterDot;Î”&it;â€ƒ&it;v>V2Î”&it;â€ƒ&it;Va&it;â€ƒ&it;n&it;â€ƒ&it;dL&CenterDot;Î´&it;â€ƒ&it;v<V2Î”&it;â€ƒ&it;Vwhere:L is the fiber length; &Dgr;v is the frequency spectrum width of the optical radiation; &dgr;v is the modulation signal frequency bandwidth; V is mean velocity of the optical radiation modes propagating along the fiber; and &Dgr;V is maximum difference between propagation velocities of the modes exited by the radiation in the fiber; and transmitting the modulated optical radiation as a beam from an output of the multimode fiber over a free-space optical link.