Polarization-mode dispersion compensation performance of optical DQPSK is studied in this paper. Firstly, the
simulation model for the back to back system of optical DQPSK is established by using Matlab. The optical power
spectra and eye diagram of different DQPSK modulation formats are obtained. Then, we adopt two pseudo random
binary sequences as input data streams. In the back to back DQPSK system, by means of precoding, modulation and
demodulation we obtain exactly the same as the original signal. The system for simulation is verified. At last, we add the
polarization-mode dispersion compensation program module to the back to back DQPSK system. The result is shown
that the modulation formats with smaller bandwidth have better PMD compensation performance. and that PMD
compensation performance of DQPSK is better than that of OOK and DPSK. CSRZDQPSK combines the
carrier-suppressed feature of CSRZ formats and specific spectrum characteristic of DQPSK formats, thereby it has the
best performance of PMD compensation performance.
We established the DPSK generating and receiving system, and realized the different kind of DPSK formats. Then we
demonstrated the experiment of automatic PMD compensation in 10Gb/s NRZ-DPSK, RZ33-DPSK, RZ50-DPSK, and
RZ67-DPSK systems. Using the particle swarm optimization algorithm in these DPSK systems, the optical signals were
successfully recovered instantly from PMD induced distortion after compensation.
We study the polarization mode dispersion (PMD) compensation performance of different modulation formats. Firstly,
we analyze the relationship between the signal's degree of polarization (DOP) and differential group delay (DGD) of
different modulation formats. The results show that the differential phase-shift keyed (DPSK) modulation formats are
more suitable for PMD compensation system than the ON-OFF keying (OOK) modulation formats because the DOP-DGD
curves of DPSK signals are monotonic and it is easy to search the global maximum. Secondly, we study the PMD
compensation performance of the mentioned modulation formats with DOP as feedback signal. It is shown that the
modulation formats with smaller bandwidth have better PMD compensation performance, and that PMD compensation
performance of DPSK formats are better than that of OOK formats. CSRZDPSK combines the carrier-suppressed
characteristic of CSRZ format and specific spectrum characteristic of DPSK format, thereby it has the best performance
of PMD compensation.