Fiber coupler variable optical attenuator

A fiber coupled variable optical attenuator includes an optical fiber coupler mounted through a low modulus material bushing into a protective enclosure with one end clamped and another end free. The free end of the coupler is deflected by a motorized mechanism. The mechanism includes an electric step motor, a shaft providing eccentric motion, and a support/deflection component connected with the coupler in a kinematic chain, which provides lateral deflection of the coupler's free end. The structural and material parameters of the kinematic chain members are established to satisfy conditions of thermal compensation for the enclosure enveloping this chain. The free end of the coupler is equipped with a sleeve having a spherical polished surface positioned in contact with the deflection component. The enclosure is equipped with a thermal-compensating device positioned in series between the enclosure and optical fibers.