Optical Equalization of 42.7-Gbaud Bandlimited RZ-DQPSK Signals

We demonstrate the use of an optical equalizer to allow 42.7-Gbaud (85.4-Gb/s) return-to-zero differential quadrature phase-shift keyed signals to better tolerate the narrow optical filtering required in high-spectral-efficiency systems. The equalizer passbands are repetitive, enabling the equalization of multiple channels.