Fang Xinyue, He Wenjun, Wang Wen, Liu Yi, You Yajun, Yan Qing, Hou Yafei, Wu Zepeng, Yu Lei, Yan Songquan, Li Mingxing, He Jian, Chou Xiujian
State Key Laboratory of Dynamic Measurement Technology, School of Instrument and Electronics, North University of China, Taiyuan 030051, China.
School of Aerospace Engineering, North University of China, Taiyuan 030051, China.
Micromachines (Basel). 2025 Feb 12;16(2):209. doi: 10.3390/mi16020209.
An all-optical single-longitudinal-mode (SLM) forward Brillouin microwave oscillator (FB-MO) with an unbalanced Fiber Mach-Zehnder interferometer (UF-MZI) for microwave photonics (MWP) generation is proposed and experimentally investigated. UF-MZI consists of an optical coupler (OC), a polarization controller (PC), and two asymmetric length arms with 5 km and 500 m single-mode fibers (SMFs), which implements two unbalanced length feedback rings that are connected to one another. One long-length ring with a forward Brillouin gain cooperates with the other short-length ring to maintain a spectral Vernier effect and improve the effective free spectral range (FSR). By contrast with traditional optoelectronic oscillators (OEOs), this design does not require any photoelectric conversion devices and additional modulation, avoids external electromagnetic interference, and side-mode suppression and linewidth are favorable. Experimental results reveal that the 3-dB linewidth of the all-optical SLM FB-MO with UF-MZI is about 140 Hz. The acoustic-mode and side-mode suppression ratios are 26 dB and 31 dB. Within 60 min of the stability experiment, the power and frequency stability fluctuation were ±1 dB and ±100 Hz. Thanks to its long main ring cavity length, our all-optical SLM FB-MO with UF-MZI maintains good phase-noise performance. The measurement shows that a phase noise as low as -120 dBc/Hz at an offset frequency of 100 kHz is achieved. This SLM MWP generation technology holds great potential for applications in radar monitoring and wireless communication systems.
提出并通过实验研究了一种用于微波光子学（MWP）产生的具有不平衡光纤马赫-曾德尔干涉仪（UF-MZI）的全光单纵模（SLM）前向布里渊微波振荡器（FB-MO）。UF-MZI由一个光耦合器（OC）、一个偏振控制器（PC）以及两个分别具有5 km和500 m单模光纤（SMF）的非对称长度臂组成，它实现了两个相互连接的不平衡长度反馈环。一个具有前向布里渊增益的长长度环与另一个短长度环协作，以维持光谱游标效应并改善有效自由光谱范围（FSR）。与传统的光电振荡器（OEO）相比，该设计不需要任何光电转换器件和额外的调制，避免了外部电磁干扰，并且边模抑制和线宽都很理想。实验结果表明，带有UF-MZI的全光SLM FB-MO的3 dB线宽约为140 Hz。声模和边模抑制比分别为26 dB和31 dB。在60分钟的稳定性实验中，功率和频率稳定性波动分别为±1 dB和±100 Hz。由于其主环腔长度较长，我们带有UF-MZI的全光SLM FB-MO保持了良好的相位噪声性能。测量结果表明，在100 kHz的偏移频率下实现了低至-120 dBc/Hz的相位噪声。这种SLM MWP产生技术在雷达监测和无线通信系统中具有巨大的应用潜力。
