一种基于相位调制器的40 GHz OFDM-ROF系统实验研究

Experimental research about a 40 GHz orthogonal frequency division multiplexing radio-over-fiber system based on optical phase modulator

实验研究了一种基于相位调制器(PM)并级联强度调制器(IM)实现40 GHz毫米波传输正交频分复用(OFDM)信号的光纤无线通信(ROF)系统。在中心站,采用20 GHz的射频(RF)信号驱动PM,调节驱动信号的强度,使输出的信号经光纤布拉格光栅(FBG)滤除中心载波后再送入IM。2.5 Gbit/s的OFDM信号直接调制在光毫米波上,经过50 km标准的单模光纤(SSMF)传输到基站。在基站,光调制信号经光电转换器(PD)转换成电调制信号,再与RF信号混频,恢复出基带OFDM信号。实验结果表明,在无色散补偿、误码率(BER)为10-3的条件下,下行链路中2.5 Gbit/s的OFDM信号经光纤传输50 km后,其功率代价小于1 dB,而且信号的星座图依然较好。

We demonstrate a 40 GHz radio-over-fiber system using an optical phase modulator along with an intensity modulator to generate an optical millimeter-wave with OFDM signals.In the central station,40 GHz optical millimeter-wave with OFDM signals is generated by using an optical phase modulator which is driven by the 20 GHz RF signals.Then the optical carrier is filtered out by an FBG.2.5 Gbit/s OFDM signals are modulated on 40 GHz optical mm-wave directly and transmitted to the base station over 50 km standard single-mode fiber（SSMF）.In the base station,the optical mm-wave signals are converted to electrical signals after optical-electrical conversion,and the down-converted OFDM signals are detected after mixing with the local oscillators.The experimental results show that at the BER of 10^-3 and without dispersion compensation,the power penalty of the downlink OFDM signals transmitted over 50 km SMF-28 is less than 1 dB,and the constellation figure is still good.