基于注入锁定激光器的低噪声微波光子变频技术

Low-noise microwave photonic frequency conversion technology based on injection-locked laser

提出并仿真论证了一种利用马赫-曾德尔调制器(Mach–Zehnder modulator,MZM)以及注入锁定激光器的微波光子变频方法。上支路激光经射频(radio frequency,RF)信号调制实现载波抑制调制后经过滤波器滤出光边带,下支路激光经本振(local oscillator,LO)信号调制实现单边带调制后通过注入锁定激光器实现光的滤波放大,两束光耦合后进入光电探测器(photodetector,PD)拍频实现上下变频。该结构充分利用了注入锁定激光器能够被输入激光锁定的特性,可以获得完美的本振光,因此,能够通过差频产生更好的微波信号。仿真结果表明,该系统无杂散动态范围(spurious free dynamic range,SFDR)大于90dB·Hz^(2/3),噪声系数(noise figure,NF)小于30dB。

A microwave photon frequency conversion method is put forward and demonstrated using Mach-Zehnder modulator(MZM)and injection-locked laser.In the upper branch,the laser is modulated by the radio frequency(RF)signal to realize the carrier suppression modulation and then the optical sideband is filtered by the filter;in the lower branch,the laser is modulated by the local oscillator(LO)signal to realize single sideband modulation and then filtered and amplified by the injection-locked laser.After the coupling of the two beams,the light enters the photodetector(PD)beat frequency to realize up and down frequency conversion.The structure makes full use of the feature that the injection-locked laser can be locked by the input laser,and can obtain perfect local oscillator light,so it can generate better microwave signal through the difference frequencies.Simulation results show that the spurious free dynamic range(SFDR)of the system is greater than 90dB·Hz^(2/3)and the noise figure(NF)is less than 30dB.