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.

中文翻译：

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在散斑仪中由飞安计解析的多个激光波长的同时测量

光学科学的许多领域都需要精确测量光谱。基于激光散斑的设备有望实现紧凑的波长测量，并证明了单波长激光场具有千分尺级别的灵敏度。使用这种方法测量多模光谱将很有吸引力，但是目前仅限于皮米分辨率。在这里，我们提出了一种提高基于斑点的多波长测量的分辨率和精度的方法。我们在由一根1-m长的阶跃折射率多模光纤和快速相机组成的设备中同时测量多个波长。使用主成分分析可以以0.2 fm的精度检索相距仅1 fm的独立波长。