基于相移超结构光栅的ROF单边带调制系统（英文）

Single-sideband modulated radio-over-fiber system based on phase-shifted superstructure fiber Bragg grating

提出了一个利用相移超结构光栅构建的典型ROF单边带调制系统。改变倾斜角,光栅就会呈现不同的传播特性。将不同的相移插入光栅的不同位置就会得到不同的透射谱特性。因此该光栅可视为滤波器应用于单边带调制系统中。反射谱的负斜率特性使得低阶边带会经历更高的衰减。所以,仅仅使用一个相移超结构光栅就可以简单地实现双边带到载波单边带的转换。与此同时,还可以通过改变光栅的倾斜角优化光载波抑制比。在实验中,60 GHz的毫米波信号产生的同时光载波抑制比也由33.02 dB优化到1.31 dB,经过30 km光纤传输后的最小误码率可以达到1.966e-44,所以仅仅通过一个相移超结构光栅就可以大大提高链路性能。

A prototype for the typical optical single-sideband（SSB） modulated radio-over-fiber （ROF） system was presented by employing a phase-shifted superstructure Bragg grating. The grating has different transmission characteristics with different oblique angle. So, the different transmission peak could be obtained with different phase shift inserted into different positions. Then it was used in SSB modulation scheme as a filter. In the scheme, the lower sideband experiences higher attenuation due to the negative slope in reflectivity spectrum. Thus the conversion from dual-sideband（DSB） to single sideband with carrier（SSB＋C） can be easily achieved by using only one phase-shifted superstructure fiber Bragg grating. Also, the optical carrier-to-sideband ratio（OCSR） can be optimized by using grating with different oblique angle. In this paper, the OCSR could be optimized from 33.02 dB to 1.31 dB and a 60 GHz millimeter-wave was detected after photodiode. What＇s more, a min BER of 1.966e-44 with 30-km fiber length was implemented which means that only using one phase-shifted superstructure FBG can improve the link performance greatly.