POLARIZATION-INDEPENDENT, LINEAR-TUNED INTERFERENCE FILTER WITH CONSTANT TRANSMISSION CHARACTERISTICS OVER 1530-1570-NM TUNING RANGE

We present a polarization independent optical tunable filter (OTF) wit h nearly constant transmission characteristics over 1530-1570 nm, The tuning is achieved by horizontally sliding an interference filter, res ulting in a very low polarization dependent loss (PDL) < 0.1 dB and ne arly constant characteristics over the tuning range. By cascading inte rference filters in double or triple stage, narrower bandwidth charact eristics are obtained allowing for smaller channel spading in waveleng th division multiplexing (WDM) systems, Experimental results for PDL, loss, and bandwidth are presented and compared to those of angle-tuned filter, The proposed OTF has shown superior performance promising a p ractical solution for dense WDM applications.