2.5 Gbit/s码位重叠快跳频光码分多址实验系统

设计并实现了单用户、数据速率2.5 Gbit/s的码位重叠快跳频光码分多址(SO-FFH OCDMA)实验系统。采用波长数为7和码长为4的单重合码,在数据速率2.5 Gbit/s时设计和制作了基于光纤布拉格光栅(FBG)的光编码/解码器,并测试了光编码器和光解码器的频谱图。脉冲发生器产生2.5 Gbit/s的非归零(NRZ)脉冲信号,外调制放大自发辐射(ASE)宽带光源后,通过光环行器进入光编码器进行光信号的扩频编码。编码后的光信号经掺铒光纤放大器(EDFA)放大后,输入到光解码器进行扩频解码,并通过2.5 Gbit/s接收模块转换为电信号。从解码信号的波形看,在用户数据速率为2.5 Gbit/s时,该系统能够正确解码用户的数据信息。实验结果表明,相对于传统的快跳频光码分多址系统,码位重叠快跳频光码分多址可大大提高用户的数据速率。

Experiment on 2.5 Gbit/s Symbol Overlapping Optical Fast Frequency-Hopping Code Division Multiple Access System

Experiment on 2.5 Gbit/s symbol overlapping fast frequency-hopping optical code division multiple access (SO-FFH OCDMA) system with single user is designed and demonstrated. Under user′s data rate 2.5 Gbit/s, fiber Bragg grating based optical encoder and decoder are designed and fabricated employing one-coincidence sequence, which the number of wavelengths is seven and code length is four. The spectra of optical encoder and decoder are measured. Pulse generator generates 2.5 Gbit/s non-return zero (NRZ) pulse signal, which is used to externally modulate amplified spontaneous emission (ASE) broadband source, and then optical signal is fed into optical encoder to spread spectrum. At the receiver, an Erbium-doped fiber amplifier (EDFA) is employed to amplify the encoded optical signal, then optical signal is fed into the decoder, and is also converted into electrical signal by 2.5 Gbit/s receiver module. It can be shown from the waveforms of decoded optical signal and the electronic signal that, user′s data can be decoded correctly at 2.5 Gbit/s data rate. Experiment shows that compared with traditional FFH OCDMA, SO-FFH OCDMA has much higher user′s data rate.