Effect of in-line filtering in WDM optical access networks

A study of inline optical filtering in wavelength division multiplexing access networks based on intensity modulation and direct-detection is presented. The system was experimentally tested with several bitrates and filter bandwidths representing the effect of passing through an arrayed waveguide grating. A minimum filter bandwidth of 0.08nm was required to avoid penalties higher than ldB at BER=2·10^-4 for 10Gb/s bitrate. In addition, the influence of neighbor channels and filter bandwidth was also evaluated. In a splitter-based network the minimum wavelength separation to keep penalty below ldB between users was 0.25nm whereas it reduced to 0.1nm with filters improving the spectral efficiency by 2.5 times.