研究了基于相位调制原理的新型调制格式差分八相相移键控(D8PSK),给出了串联和并联两种信号生成方案,对包括非归零码(NRZ)、33%占空比归零码(33%RZ)、50%占空比归零码(50%RZ)、载波抑制归零码(CSRZ)4种不同码型的生成方式进行了说明,对信号的接收过程和预编码公式进行了理论推导,并对系统进行了仿真。仿真系统中信号总速率达到100Gbit/s,信号生成采用串联方式,信号接收采用4个马赫一曾德尔时延干涉仪(MZI)平衡检测接收机,色散补偿方式采用对称补偿,通过眼图可以看到其接收效果良好。最后对不同码型的D8PSK与DQPSK系统在抵抗群速度色散效应、非线性效应及偏振模色散效应3种主要影响系统传输性能的因素方面进行了分析比较。当眼图张开度代价为ldB时,CSRZ—D8PSK信号的群速度色散容限、非线性容限及偏振模色散容限分别为190ps/nm、4.4dBm及24ps,结果表明其具有较好的传输性能。
Base on phase modulation, a new modulation format of differential 8-ary phase-shift keying (DSPSK) was studied; two generating schemes and four different mark-space ratio signals such as NRZ- D8PSK, RZ-DSPSK with 33% or 50% duty cycle and CSRZ-DSPSK were presented, respectively. The receiving processes and the differential precoder formula were derivated, and the system was demonstrated by simulation. In the simulation, the total rate of the DSPSK signal reached 100 Gbit/s, with series modulation generator, four Mach-Zehnder interferometers (MZI) balance detection receiver and symmetrical-compensation transmission model. As a result, the receiving effect is good in eye diagram. Moveover, under different mark-space ratio, the transmission performance influenced in the group velocity dispersion (GVD) impairment, nonlinear impairment and polarization mode dispersion (PMD) impairment were analyzed and compared with DQPSK. When the eye open penalty (EOP) was 1 dB, CSRZ-DSPSK signal's tolerances of GVD, nonlinear and PMD were 190 ps/nm, 4.4 dBm and 24 ps. The results show that it has better transmission performance in general.