Bruce Graham D, O'Donnell Laura, Chen Mingzhou, Facchin Morgan, Dholakia Kishan
Opt Lett. 2020 Apr 1;45(7):1926-1929. doi: 10.1364/OL.388960.
Many areas of optical science require an accurate measurement of optical spectra. Devices based on laser speckle promise compact wavelength measurement, with attometer-level sensitivity demonstrated for single wavelength laser fields. The measurement of multimode spectra using this approach would be attractive, yet this is currently limited to picometer resolution. Here, we present a method to improve the resolution and precision of speckle-based multi-wavelength measurements. We measure multiple wavelengths simultaneously, in a device comprising a single 1-m-long step-index multimode fiber and a fast camera. Independent wavelengths separated by as little as 1 fm are retrieved with 0.2 fm precision using principal component analysis. The method offers a viable way to measure sparse spectra containing multiple individual lines and may find application in the tracking of multiple lasers in fields such as quantum technologies and optical telecommunications.
光学科学的许多领域都需要对光谱进行精确测量。基于激光散斑的设备有望实现紧凑的波长测量，对于单波长激光场已展示出阿秒级的灵敏度。使用这种方法测量多模光谱将很有吸引力，但目前其分辨率仅限于皮米级。在此，我们提出一种提高基于散斑的多波长测量分辨率和精度的方法。我们在一个由一根1米长的单模阶跃型多模光纤和一台高速相机组成的设备中同时测量多个波长。使用主成分分析，能以0.2飞米的精度检索出间隔小至1飞米的独立波长。该方法为测量包含多条单独谱线的稀疏光谱提供了一种可行途径，可能在量子技术和光通信等领域的多激光跟踪中得到应用。
