抑制全正色散光纤超连续谱产生中的短期偏振噪声及相关光谱退相干
Suppressing Short-term Polarization Noise and Related Spectral Decoherence in All-normal Dispersion Fiber Supercontinuum Generation.
作者信息
Liu Yuan, Zhao Youbo, Lyngsø Jens, You Sixian, Wilson William L, Tu Haohua, Boppart Stephen A
机构信息
Biophotonics Imaging Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
NKT Photonics A/S, Blokken 84, 3460 Birkerød, Denmark.
出版信息
J Lightwave Technol. 2015 May 1;33(9):1814-1820. doi: 10.1109/JLT.2015.2397276.
The supercontinuum generated exclusively in the normal dispersion regime of a nonlinear fiber is widely believed to possess low optical noise and high spectral coherence. The recent development of flattened all-normal dispersion fibers has been motivated by this belief to construct a general-purpose broadband coherent optical source. Somewhat surprisingly, we identify a large short-term polarization noise in this type of supercontinuum generation that has been masked by the total-intensity measurement in the past, but can be easily detected by filtering the supercontinuum with a linear polarizer. Fortunately, this hidden intrinsic noise and the accompanied spectral decoherence can be effectively suppressed by using a polarization-maintaining all-normal dispersion fiber. A polarization-maintaining coherent supercontinuum laser is thus built with a broad bandwidth (780-1300 nm) and high spectral power (~1 mW/nm).
人们普遍认为，仅在非线性光纤的正常色散区域产生的超连续谱具有低光学噪声和高光谱相干性。基于这一认识，近年来扁平全正色散光纤得到了发展，以构建通用的宽带相干光源。有点令人惊讶的是，我们发现这种类型的超连续谱产生过程中存在大量短期偏振噪声，过去这种噪声被总强度测量所掩盖，但通过线性偏振器对超连续谱进行滤波可以很容易地检测到。幸运的是，使用保偏全正色散光纤可以有效抑制这种隐藏的固有噪声以及伴随的光谱退相干。这样就构建了一个带宽宽（780 - 1300 nm）且光谱功率高（约1 mW/nm）的保偏相干超连续谱激光器。
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