Stabilization of a delay interferometer for variable bit-rate DPSK receiver from 40 Gbit/s up to 160 Gbit/s

We demonstrate stabilization of a delay interferometers (DI) for variable bit-rate DPSK receiver from 40 Gbit/s up to 160 Gbit/s using a wavelength tunable CW laser. The phase difference is continuously tunable by tuning the CW laser. The BER of the received 41.25 Gbit/s DPSK signal was successfully stabilized. No noticeable degradation was observed in the eye patterns when the bit rate is 82.5 Gbit/s and 165 Gbit/s.