Variable optical attenuator for optical transmission or measuring system - has successive high attenuation sections coupled to optical couplers with plug or splice connections at free ends

摘要

The attenuation element uses an glass optical fibre (7) with successive sections (1, 3, 5) having a higher attenuation per unit length than the optical fibre. Each higher attenuation section is coupled to one gate of a coupler (2, 4, 6), with plug or splice connections (8...13) at the free ends of the higher attenuation sections and at least one gate of each coupler. Pref. each of the higher attenuation sections is wound into a coil with a dia. of between 30 and 60 mm, the optical fibre having an attenuation of between 0.1 dB/m and 40 dB/m. ADVANTAGE - Relatively low-cost attenuator with good reflection attenuation characteristics.