Adjustable attenuator for optical transmission system

摘要

An improved variable rate attenuator (VOA) is disclosed, which is used in an optical signal transmission system for testing (and other) purposes. In an optical fiber data transmission system, the VOA can be used to determine how much attenuation of the light beam can be tolerated without causing excessive bit error rate (BER) in data transmission. The improved VOA is a blocker having a vane-like structure which is gradually rotated into a collimated beam to cause attenuation. Because the movement vector of the edge of the blocker perpendicular to the collimated beam gradually becomes less for a given increment of blocker rotation, resolution of the attenuation is improved.