频谱分割波分复用无源光网络及色散影响

Spectrum-Sliced Wavelength Division Multiplexed Passive Optical Networks and Effects of Chromatic Dispersion

频谱分割是使用窄带光滤波器选择宽带光源光谱的一个切片的WDM技术,在波分复用无源光网络(WDM-PON)中采用波分复用器((MUX)进行频谱分割,能够实现光网络单元(ONU)的无色化。模型分析表明由于频谱分割的作用,使得波分复用器光通带外的频谱成分被过滤,减小了宽带光源的色散影响。在20 nm CWDM标准信道间隔下,能够以不超过1 dB的光功率代价支持155 Mb/s信号在20 km的G.652常规光纤上传输;在0.8 nm DWDM信道间隔下则能够支持2.5 Gb/s信号传输,色散引起的光功率代价低于0.5 dB。采用中心波长为1550 nm、谱宽70 nm、输出功率为—10 dBm的LED,研制了125 Mb/s速率信号直接调制的无色ONU。在信道间隔为20 nm、光纤长度为20 km的4波长WDM-PON系统上进行测试,色散等因素引起的光功率代价小于1 dB,系统光功率余量则超过5.6 dB。

Spectrum-slicing is an attractive WDM technique for realizing colorless ONUs in wavelength division multiplexed passive optical network （WDM-PON）. It uses wavelength multiplexer （λMUX） as optical filters to obtain a spectral slice of light from a broadband light source （BLS） and modulates encode data onto the slice. A theoretical analysis elucidates that the effects of chromatic dispersion will reduce because the spectrum outside the bandwidth of ;tMUX will be filtered out after spectrum slicing. At the 20 nm CWDM channel spacing, 155 Mb/s per channel at distance of 20 km on a G. 625 fiber is supported with optical power penalty less than 1 dB; while at 0.8 nm DWDM channel spacing, 2.5 Gb/s per channel is supported with optical power penalty less than 0.5 dB. Direct modulation colorless ONU at 125 Mb/s is proposed and demonstrated by using LED with centre wavelength at 1550 nm, output power of -10 dB and a bandwidth of 70 nm. A four-channel WDM-PON over 20 km fiber with channel spacing of 20 nm is tested. The result shows optical power penalty caused by chromatic dispersion is less than 1 dB and optical power margin is more than 5.6 dB.