Optical DPSK/Heterodyne-Detection Scheme Using Two Polarization Planes.

This paper proposes the dual polarization DPSK (DPDPSK) as an extension of the polarization modulation to the narrowband system. The basic performances are examined. First, it is shown that the proposed scheme occupies half of the signal bandwidth of the polarization modulation scheme, the receiver configuration is the same as that of the polarization modulation, and the phase noise insensitivity, which is the feature of the polarization modulation, is utilized effectively in the proposed system. Assuming a receiver with the double-filtering configuration, a theoretical analysis for the receiver error rate is presented, considering the envelope fluctuation due to the phase noise at the bandpass filter (BPF) output, as well as the additive noise suppression by the lowpass filter (LPF) in the demodulator. It is shown that the optimal BPF bandwidth exists that maximizes the receiver sensitivity. [ABSTRACT FROM AUTHOR]