基于布里渊光纤振荡器的可调谐窄带微波光子滤波器研究

Tunable narrowband microwave photonic filter based on brillouin fiber oscillator

为了使微波光子滤波器兼具宽调谐范围与高频率选择性,本文基于窄线宽单纵模光纤受激布里渊振荡器首次提出并验证了一种具有宽调谐范围、窄滤波带宽特性的微波光子滤波器。该滤波器的核心是腔长为10 m的布里渊光纤振荡器,受激布里渊散射泵浦光与光载波信号分别由两个不同的可调谐激光器提供,布里渊增益与光调制信号相互作用后,利用该布里渊光纤振荡器压缩光谱线宽,实现窄带微波光子滤波;通过简单地改变泵浦光波长,实现滤波器通带大范围稳定调谐。实验结果表明,该微波光子滤波器在0~20 GHz的频率范围内可稳定调谐,带外抑制比约为20 dB,其3-dB带宽和最大Q值分别为6.2 kHz和3.222×10^(6)。本文提出的单通带微波光子滤波器不仅具有目前已知的最高Q值,同时具有宽可调性、高带外抑制和结构简单等优势。

In order to make sure a microwave photonic filter both have wide tuning range and high frequency selectivity,a microwave photonic filter with a wide tuning range and narrow filter bandwidth based on a Brillouin oscillator is proposed and verified for the first time.The core of the filter is a Brillouin fiber oscillator with a cavity length of 10 m,and the stimulated Brillouin scattering pump and optical carrier signal are provided by two different tunable lasers.After the Brillouin gain spectrum interacts with the optical modulation sideband,the Brillouin fiber oscillator is used to narrow the spectral linewidth to realize narrowband microwave photonic filtering.By changing the pump wavelength,the filter passband can be tuned stably.The experimental results show that the microwave photonic filter can be stably tuned in the frequency range of 0-20 GHz.The out-of-band rejection ratio is found to be about 20 dB,and its 3-dB bandwidth and maximum Q value are 6.2 kHz and 3.222×10^(6),respectively.To the best of our knowledge,this is the highest value of a high-Q single-passband MPF reported to date.At the same time,the MPF has the advantages of wide tunability,high side mode suppression and a simple structure.