Method and device for controlling received power level in free space optical communication system

Abstract

A free space optical communication system is disclosed whereby the received power at the receive optical fiber is reduced by adjusting the transmitted light beam and the receive optical fiber with respect to each other when a specified power threshold is exceeded so that they intersect not at a point of focus, but at a point of divergence of the transmitted beam. The transmitted beam may be diverged by moving the transmit optical fiber to a point in front of the focal plane of the transmit telesco pe along the longitudinal axis of that telescope until at least a portion of th e beam is incident upon the receive optical fiber. This causes the transmitted beam to diverge and, accordingly, the cross-sectional area to increase at the point where it is incident upon the receive telescope. As a result, the cros s- sectional power per unit area of the transmitted beam at the receive telescope is reduced which correspondingly reduces the power that is incident upon the receive optical fiber.

Description

technical field [0001] The present invention relates generally to data communication systems, and more particularly to free space optical data communication networks. Background technique [0002] To overcome traditional communication systems that use physical wires or cables to connect two or more locations, they are usually limited to relatively low-speed, low-capacity applications. Recently developed systems use optical fiber. Fiber optics, however, still require the use of physical fiber optic cable connections. To solve this problem, systems have been developed that use free space to emit one or more data-modulated beams. Systems using such beams greatly increase data rates and capacity rates, up to 10 gigabits per second, compared to traditional wire-based systems, while avoiding the need for laying fiber optic cables to physically connect various locations in the system in traditional communication systems infrastructure costs incurred. Free-space optical communica...

AI Technical Summary

Problems solved by technology

[0005] The present invention substantially solves the aforementioned problem of receiving an excessively high power beam from the transmitting telescope at the receiving telescope during communication

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