基于激光器RIN抑制的宽带低噪声微波光传输技术

Broadband Low-noise Microwave Optical Transmission Technology Based on Laser RIN Suppression

摘要:

微波光子链路中的核心器件激光器、调制器、光电探测器均为有源器件,在微波信号的电光光电转换过程中会引入额外的噪声,导致微波信号的噪声性能恶化,高的噪声系数会降低电子信息系统的灵敏度、动态范围、探测精度等关键性能指标,因此抑制噪声成为实现高性能微波光子系统的关键。文章针对当前激光器噪声较高的限制,提出采用常规分布反馈(DFB)激光器与光放大器、窄带光子滤波相组合的方式来抑制激光源噪声,实现微波光子链路的宽带低噪声。建立了微波光子链路传输模型,分析了链路性能与器件参数之间的映射关系。实测对比了采用该组合光源方案与常规微波光子链路的噪声性能,结果表明采用高功率光源结合光滤波可对激光器远端相对强度噪声(RIN)实现高的抑制,通过优化,噪声系数较常规水平可改善15dB以上。

Abstract:

Lasers, modulators, and photodetectors at the core of the microwave photonic link are active devices that introduce additional noise during the electro-optical-electrical conversion of microwave signals, deteriorating the noise performance of the microwave signals and thereby reducing the sensitivity, dynamic range, detection accuracy, and other key performance indicators of the electronic information system. Therefore, noise suppression has become critical to achieving high-performance microwave photonic systems. To overcome the limitations of current lasers with high noise, this study proposes the use of conventional distributed feedback lasers combined with optical amplifiers and narrow-band photonic filtering to suppress laser source noise and realize the broadband low-noise capabilities of the microwave photonic link. This study develops a microwave photonic link transmission model and analyzes the mapping relationship between the link performance and device parameters. The noise performances of the combined light source scheme and the conventional microwave photonic link are measured and compared, and the results show that the use of a high-power light source combined with optical filtering can achieve a high suppression of laser distal relative intensity noise (RIN). Through optimization, the noise figure can be improved by more than 15dB compared with the conventional level.