Wavelength independent receiver for low cost and reduced complexity WDM DQPSK systems

A new concept for wavelength independent receiver for low cost and reduced complexity wavelength division multiplexing (WDM) differential quadrature phase shift keying (DQPSK) system is presented. The main idea behind the receiver design is the use of a single optical delay interferometer to demodulate the in-phase (I) and quadrature-phase (Q) components of the WDM signal before entering the demultiplexing unit of the receiver. The receiver is validated through BER measurements by means of discrete components showing a negligible variation (less than 1dB) of the required OSNR at BER=10^-5 over the C band. The design of a possible photonic integrated version exploiting bidirectional propagation in arrayed waveguide grating filters is also presented.