Abstract: A high speed optical receiver for receiving a substantially diminished optical signal. An optical amplifier amplifies the diminished optical signal at least several db and an ultra narrow-band filter filters the noise generated in the optical amplifier to produce a filtered amplified optical signal which is detected by a fast response photo detector. In a preferred embodiment the optical amplifier is a semiconductor laser amplifier. In this embodiment a Faraday filter provides the ultra narrow-band filtering, virtually eliminating the noise produced by the amplifier. Transmitters are described for transmitting information at a wavelength tuned to the ultra narrow-band filters.

Abstract: A laser communication device for transmitting and receiving information imposed on laser beams. A transmitting unit and a receiving unit are implemented based on atomic line filters. The transmitting unit includes a compact tunable laser locked to a selected atomic transition line. Information may be imposed on a laser beam by modulating the frequency thereof while maintaining its output power substantially unchanged.

Abstract: A portable laser communication transceiver for transmitting and receiving information imposed on laser beams. A communication signal is imposed on a laser beam having a divergence of between 1 degree and 4 degrees. The beam is directed by an operator, sighting through a telescopic viewing device, at a distant transceiver which collects light in the laser beam with a. In preferred embodiments, the transceivers are handheld and each comprises a microphone and earphones allowing operators to talk with each other. Digital information can also be transmitted from personal computers and other electronic information equipment at the location of each operator. In a preferred embodiment useful for military and surveying applications, a GPS, a compass and a laser ranging system is provided. This enables the operator to sight through a binocular to a target and determine its position in longitude, latitude and elevation.

Abstract: For transmitting information via laser beams to and from other similar laser communication transceivers. Each transceiver comprises a wavelength locked beacon laser providing a beacon beam. The transceivers determine the precise location of other transceivers by detecting these beacon beams with beacon receive units comprising atomic line filters matched to the beacon wavelength. Signals are transmitted by imposing an electronic signal on laser beams produced by one or more signal laser devices. These signals are directed with precision at other transceivers, and the signal beams are detected with very narrow field of view signal receive units. In a preferred embodiment, these transceivers are installed on 66 satellites in low earth orbit and on selected mountain tops on earth to provide a global communication system.