基于受激布里渊散射的高精度多微波频率测量

为实现高精度大范围多微波频率测量, 利用双平行马赫曾德尔调制器(dual parallel Mach-Zehnder modulators, DPMZM)分别对未知信号和扫描信号进行抑制载波单边带调制, 并分别作为信号光和泵浦光输入到色散位移单模光纤中, 当两者满足一定的频率关系时, 信号光会得到放大, 通过测量输出光功率值即可估计出待测信号的频率值。该方案利用双阶段受激布里渊散射结构降低了受激布里渊散射增益线宽。另外, 通过设置DPMZM的调制参数, 即可利用低频段的扫描信号实现高频段的频率测量, 降低了方案的实现复杂度。为进一步提高算法精度, 利用测量的光功率值建立幅度比较函数, 通过计算可得频率测量误差, 通过误差修正可提升方案的测频精度。最后, 通过实验仿真证实了方案的有效性, 测量误差为±3 MHz。

High-resolution multiple microwave frequency measurement based on stimulated Brillouin scattering

A high resolution multiple microwave frequency measurement scheme based on stimulated Brillouin scattering is proposed. The unknown microwave signal and sweep microwave signal are carrier suppressed single sideband modulated via dual parallel Mach-Zehnder modulators (DPMZM) which are set as the signal light and pump light of the dispersion shift single-mode fiber. With the phase matching between the signal wave and the pump wave, the stimulated Brillouin scattering will be stimulated and the low frequency signal optical will be amplified. Then, the unknown signal can be estimated by measuring the signal power of the output signal. Then, the dual stage Brillouin system is utilized in the scheme to reduce the Brillouin gain spectrum linewidth. Besides, by adjusting some parameters of the DPMZM, the high frequency measurement can be realized with a relatively low-frequency sweep signal which can reduce the system complexity. Furthermore, the optical power values of the output are utilized to generate an amplitude comparison function which can provide a frequency estimation error to power mapping. Then, the estimation accuracy can be further improved via error correction. The proposed scheme is verified by numerical simulations which demonstrate that the measurement error is less than ±3 MHz.