双光频梳辅助的微波频率测量方法

Microwave Frequency Measurement Using Dual Optical Frequency Combs

为实现大频率范围内多微波频率的高精度即时测量,提出了一种基于双光频梳和法布里-珀罗滤波器(Fabry-Perot filter,FPF)的微波频率测量方案。将待测微波信号通过单边带调制加载在一路光频梳上进行频率复制,再将调制后的光信号通过一个法布里-珀罗滤波器进行信道分割。FPF的输出信号和另一路光频梳耦合后通过光解复用器实现信道化接收。通过设置合适的系统参数,可使得每个信道输出的拍频信号在同一窄带中频频段内。基于频率-光功率映射的原理,通过判断信号的存在性即可确定未知信号所处的频率段,实现信号频率的粗估计。通过对目标信道输出的微波信号进行采样、模数变换和信号处理可实现未知信号频率的高精度测量。通过实验仿真验证了所提方案的有效性,频率测量误差在±2.5 MHz内。

A novel photonic technique for microwave frequency measurement scheme based on dual optical frequency combs and Fabry-Perot filter is proposed in order to instantaneously measure multiple microwave frequencies over a wide bandwidth.The unknown microwave signal is loaded on one optical frequency comb(OFC)via a single sideband modulator to realize multicasting a wideband RF signal.Then,the frequency components of the output wideband signal are sliced into a number of parallel portions via a Fabry-Perot filter.After combining the two OFCs via a coupler,the different optical wavelengths are separated by an optical demultiplexer which can realize channelization.The input RF signal in each channel can be down-converted to intermediate-frequency signal by simply adjusting the system parameter.Thus,the system coarsely estimates the frequency band by determining the presence or absence of signal based on the frequency-optical power mapping principle.Furthermore,the high precision frequency measurement can be realized by sampling,analog to digital conversion and processing to the output signal of the target channels.Finally,an experiment is performed to verify the proposed scheme which demonstrates that a measurement error of±2.5 MHz is achieved.