Tunable optical filters - US 5305402 A
A tunable optical filter includes an array of optical fibre located within a capillary tube and mounted on a solenoid movable support and positioned in front of a lens and diffration grating. The filter provides simultaneous tuning filtering between fibres. By coupling fibres to a ring laser and fibre to an optical receiver simultaneous tuning of a laser and receiver is possible. The filter finds particular application in passive optical networks.