Equalisation of high bandwidth optical systems by phase reversal modulators

Constant group delay and well behaved magnitude response are important characteristics of broadband communications systems. Conventionally, electronic equalisers are employed to mitigate the effect of signal distortion introduced by nonideal components within the system. However, over wide bandwidths electronic equalisation (or pulse shaping) is problematic. The authors propose a method of equalising the system response optically, by employing group-delay compensating external modulators with phase reversal electrodes. These devices may allow the construction of higher data rate systems. They demonstrate the principle by equalising the response of a 14 GHz photodiode