Electromagnetic crosstalk penalty in serial fiber optic modules

Electromagnetic crosstalk poses a serious problem within today´s advanced serial communication modules. A major detrimental effect is the degradation of receiver sensitivity in the presence of crosstalk noise. The mitigation of crosstalk penalty becomes increasingly more challenging as data rates increase for higher throughput and as module sizes shrink for increased port density. This paper is a study of the primary sources of crosstalk penalty in a 2.5 GB/s serial fiber optic transceiver and a 10 Gb/s serial fiber optic transponder. A novel method for quantifying crosstalk penalty by observing a receiver´s bit-error-ratio (BER) versus transmitter to receiver signal phase is proposed. A simple coupled microstrip transmission line model is explored to demonstrate inductive crosstalk coupling.