Highly stable optical add/drop multiplexer using polarization beam splitters and fiber Bragg gratings

The wavelength-division add/drop multiplexer is one of the key devices for wavelength-division multiplexing transmission systems because of its ability to extract or add a certain wavelength at an intermediate node. We present here a novel type of multiplexer based on the use of fiber gratings and polarization beam splitters. Our multiplexer can potentially be constructed with low-cost elements, and yet shows high stability against perturbations. One of the merits of this device is its insensitivity to ambient temperature. That is because the signals from the two arms are directed to output ports not by interference but by simple addition of two orthogonally polarized beams