Design of bipolar reflectivity tapped optical fibre transversal filter

The design for a bipolar reflectively tapped filter is analysed. The effect errors in the weighting of the reflective taps, length of the delay lines and the relative time delays in the two arms of the bipolar architecture have on the filter response is simulated and manufacturing tolerances determined. These simulations show that tolerances of +or-0.5% in the mirror reflectances, +or-0.5% in the length of the individual delay elements and 0.1% for the time delay between the two arms of the filter are required to achieve a filter with a side lobe suppression of -50 dB.