In case of Differential Quadrature Phase Shift Keying transmission, the diode laser frequency instability affects the quality of the received signal. Free-running transmitters are employed to experimentally evaluate the tolerance of the interferometric DQPSK receiver to this instability. Heterodyne measure of the frequency offset is discussed for different transmitters. Experimental data are related both with BER performance and power penalty. Polarization-dependent delay impairment is isolated as well.
['Lucia Marazzi', 'Paola Parolari', 'Pierpaolo Boffi', 'Rocco Siano', 'Matteo Feroldi', 'Mario Martinelli']
DQPSK Receiver tolerance to transmitter frequency stability