Abstract: A variable optical attenuator. The variable optical attenuator has a ferrule with a hole, an optical fiber disposed in the hole of the ferrule, a lens module having a highly reflective mirror and a GRIN lens with two surfaces, and a driving device connected to the lens module for moving the lens module relative to the ferrule. In the lens module, one of the two surfaces of the GRIN lens is fixed to the highly reflective mirror, and a clearance is formed between the other surface of the GRIN lens and the ferrule. The driving device may be a piezoelectric actuator or a microactuator, and the fiber may include an input fiber and an output fiber.

Abstract: A switch device with a spiral mechanism for optical fiber is disclosed for improved reliablility.

Abstract: A system for measuring the strength of fiber optical current in an AC magnetic field by adopting Faraday effect and temperature compensation. In general, the current measurement systems that adopt Faraday effect have the structure including a Faraday element, a polarizer and an analyzer. When a light beam is directed through the Faraday element, the plane of polarization rotates according to the strength of induced magnetic field and Verdet constant in the Faraday element. The rotation affects the optical intensity sensed by the analyzer. The variation on light intensity after passing through the analyzer is converted into an electric current by a optical-electric transducer. But the accuracy of this system this system always affected by the ambient environment, wherein the major factor is the thermal effect of Verdet constant.