DPPM在相干光通信中的应用研究

Research on DPPM Technology in Coherent Optical Space Laser Communication

针对空间激光通信系统高能效高灵敏度的调制问题,对差分脉冲位置调制(DPPM)格式进行研究,并将其运用在相干光通信系统中,通过仿真及实验在系统功耗、误码(BER)性能和占用带宽中找到平衡点。实验结果表明,在直调直检和相干光通信传输系统中,在相同的传输信道,相同的传输速率为1.25 Gbit/s的DPPM信号时,两者达到硬判线所需的信号路光功率分别为-36.5和-60.0 dBm。相干传输系统对比直调直检传输系统提升了约24 dB的光功率裕度。对于实现硬判线的传输目标,传输3、6、12和24 Gbit/s速率的DPPM信号需要接收端光功率分别约为-49、-47、-42和-36 dBm。论证了采用DPPM格式/相干探测能够得到更高的灵敏度及更低的误码率。

Aiming at the modulation problem of high energy efficiency and high sensitivity in the space laser communication system,the Differential Pulse Position Modulation(DPPM)format is studied and applied to the coherent optical communication system.The balance point is found in the system considering power consumption,Bit Error Ratio(BER)performance and bandwidth occupation through simulation and experiment.The experimental results show that in the direct modulation direct detection and coherent optical communication transmission systems,the optical power of the signal path required to reach the hard line is-36.5 and-60.0 dBm respectively when the same transmission channel and the same transmission rate of 1.25 Gbit/s DPPM signal is applied.The optical power margin of the coherent transmission system is increased by about 24 dB compared with the direct detection transmission system.In order to achieve the transmission goal of the hard judgment line,the optical power of the receiver for transmitting the DPPM signal at the rate of 3、6、12、24 Gbit/s needs to be about-49、-47、-42、-36 dBm respectively.It is demonstrated that higher sensitivity and lower BER can be obtained by using DPPM format/coherent detection.