Polarization isolation follow-up on the fabrication process of birefringent fiber half-couplers

The polarization isolation of birefringent fiber half-couplers is locally observed and characterized when the device is submitted to the various steps of its fabrication. After stripping and aligning the fiber, the polarization is not affected. The mode coupling rises to the order of -40 dB after cementing and -20 dB after polishing. When the substrate is released from the jig, the set relaxes and the polarization isolation is increased to -25 dB. In addition to readily detect failure and degeneration, this procedure, joined to a geometric parameter control of the polishing step, allow a fast and precise technique to get final directional couplers with up to 25 dB of polarization isolation