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实验研究了采用一个外部调制器和一个光纤布拉格光栅(FBG)滤波器产生四倍频光载毫米波的光纤无线通信(ROF)系统。在中心站(CS),数据和射频(RF)信号通过混频后驱动外调制器,调节外调制器的直流偏置,产生抑制奇数阶边带的信号,用FBG将中心载波滤除,两个二阶边带通过光纤发送至基站。在基站(BS),两个边带在带宽为60 GHz的光电二极管中拍频,产生四倍射频信号的毫米波信号。实验显示,当射频频率为10 GHz时,可以产生频率为40 GHz的光载毫米波信号,得到的毫米波眼图和信号解调后的眼图效果都很好,功率代价小于1 dB。从眼图和功率代价两方面来看,2.5 Gbit/s的数据信号可在下行链路的光纤中传输40 km以上。
An optical fiber wireless communication (ROF) system with quadruple-frequency optical millimeter-wave generation using an external modulator and a fiber Bragg grating (FBG) filter was experimentally investigated. At the central station (CS), the data and RF signals are driven by an external modulator to adjust the DC offset of the external modulator to produce a signal that suppresses odd-order sidebands. The center carrier is filtered with FBG and two Second-order sidebands are sent over optical fiber to the base station. At the base station (BS), two sidebands are beat at a photodiode with a bandwidth of 60 GHz to produce a quadrupled millimeter-wave signal of the RF signal. Experiments show that when the RF frequency is 10 GHz, it can generate optical millimeter-wave signal with a frequency of 40 GHz. The obtained millimeter-wave eye diagram and the demodulated eye diagram result are very good, and the power cost is less than 1 dB. From eye and power cost perspectives, 2.5 Gbit / s data signals can be transmitted over 40 km in the downlink fiber.