OPEN-PATH LASER/OPTICAL COMMUNICATION SYSTEMS AND METHODS UTILIZING WAVELENGTHS BETWEEN ATMOSPHERIC AND GASEOUS ABSORPTION LINES

摘要

An open-path optical communication system has either optical or laser sources (12) and communicates between the source (12) and a detector (39). In a first embodiment, the laser source (12) includes a gas cell (14) in the laser cavity to regulate laser wavelengths based on the minimum absorption between spectral lines of the gas in the cell. The laser is tuned close to a minimum absorption wavelength and the minimum absorption line locks the laser wavelength to the minimum position. In a second embodiment, the strong absorption lines of a gas in a gas cell (34) positioned at a received site are used to provide channel isolation of the receiver. In a third embodiment, an atmospheric gas provides the channel isolation. In the fourth embodiment, individual wavelength channels are positioned between the absorption lines of atmospheric or non-atmospheric gases to prevent cross-talk between adjacent channels.