A variable optical attenuator based on silicon micromechanics

In this letter, we describe a variable optical attenuator for single mode fibers. As for its counterparts based on conventional mechanics the micromechanical attenuator operates by moving an obstructing element in the optical beam in order to adjust the light damping. The device is fabricated using the silicon micromachining technology. This allows one to integrate the electrostatic actuator together with the fiber alignment grooves and the obstructing element. With this design, an insertion loss below 1.5 dB was achieved. The response time was below 5 ms and no hysteresis was measured. The maximum attenuation was -57 dB. Backreflection attenuation was below -37 dB.