Abstract: A free-space optical communication system serves transmit/receive subscriber terminals. Each subscriber terminal includes a photo-detector and one or more sources of modulated radiation. A base terminal comprises sources of modulated optical radiation intended for the subscriber terminals and a receiving system for receiving modulated radiation from the subscriber terminals. At the base terminal, and preferably at each subscriber terminal, each source has an associated beam shaping device. The receiving system includes photo-detectors and a shared wide-angle objective implemented as a single lens. Within the base terminal, the objective lens is optically coupled only to the photo-detectors of the receiving system, and the beam shaping devices at that terminal do not have common optical elements with the lens or with each other.

Abstract: A beam generating and shaping device, for use in a free-space optical communication system provides increased uniformity in the distribution of optical radiation power, both at the output of the device and the aperture of the receiving terminal. A source provides optical radiation bearing communication information, and an optical coupler introduces radiation from the source into a multimode optical fiber, for example at an inclined angle, so as to launch a number of modes within the fiber. A mode mixer engages a portion of the multimode optical fiber. An exemplary mode mixer consists essentially of a single clamp, providing micro-bending of the fiber. An optical antenna is coupled to the cross-section formed by the distal end of the multimode optical fiber, for example, via an auxiliary lens to provide increase in output radiation beam divergence. The telescope transmits radiation emitted from the distal end of the multimode optical fiber over a free-space optical link towards the receive aperture.

Abstract: Free-space optical communication uses multibeam communications, for example between a base station and multiple remote stations. To improve efficiency and reduce complexity, the base station transmitter utilizes a single wide-angle objective lens for all of the optical beams' radiation sources. The optical radiation sources are provided with fiberoptic transmitting pigtails with output ends installed on a curved surface in relation to the single wide-angle objective lens at locations in the areas optically conjugated with the remote subscriber receivers. In a system for two-way communication, optical receivers are provided with fiberoptic receiving pigtails with input ends positioned on the curved surface at locations relative to the wide-angle objective lens, which are optically conjugated with the remote subscriber radiation sources.

Abstract: A free-space optical communication system utilizes an optical repeater system, which is installed between transmitting terminals and receiving terminals. Each optical receiver of the repeater system connects via a separate optical beam with one or more of the transmitting terminals. Two or more optical transmitters of the repeater system preferably communicate with each of the receiving terminals. Modules of the repeater system are spatially separated far enough from each other to prevent cross-talk between information on the beams, either at the receivers of the repeating system or at the receiving terminals. Receiving elements in the repeater system and/or in the destination receiving system preferably convert angular beam separation into spatial resolution between beam detectors.

Abstract: The inventive beam forming technique enables use of multimode optical fibers to couple a modulated optical beam from a radiation source to an optical emitting antenna, for free-space communications. The disclosure teaches a methodology for determining the angular and frequency spectrum parameters of the optical energy applied to the fiber as well as the parameters of the fiber so as to smooth speckle-pattern caused by multimode interference and to provide a speckle-pattern contrast at or below a maximum value at which free-space communication is most efficient.