Method of aligning birefringent optical fibers

A method of aligning a bi-refringent optical fiber so that the bi-refringence axes thereof are set in a pre-defined relation to a polarisation-sensitive component positioned within an open-topped package having an entry aperture for the fiber, comprising the steps of:

• inserting the end portion of the fiber through the aperture in the package and establishing an approximate mechanical alignment for the fiber with the component but with the fiber end still spaced from the component;
• inserting through the open top of the package an optical probe having at its free end a tip provided with an optical polariser such the tip is positioned between the end of the fiber and the component and light from the fiber falls on the polariser, the probe being arranged to feed received light to a detector;
• manipulating the free end of the fiber whilst directing light therealong to fall on the probe tip and monitoring the output from the probe until the desired polarisation alignment is achieved;
• removing the probe from the package;
• moving the fiber so that the end optically couples with the component whilst maintaining the rotational relationship between the fiber and the component;
• and
• securing the fiber in the required position.