Rosvold Jake R, Murray Joseph B, Zanini Giulia, Redding Brandon, Scarcelli Giuliano
Fischell Department of Bioengineering, University of Maryland, 8278 Paint Branch Drive, College Park, Maryland 20742, USA.
U.S. Naval Research Laboratory, 4555 Overlook Ave. SW, Washington, District of Columbia 20375, USA.
APL Photonics. 2024 Oct 1;9(10):100807. doi: 10.1063/5.0225074. Epub 2024 Oct 23.
Brillouin spectroscopy has become an important tool for mapping the mechanical properties of biological samples. Recently, stimulated Brillouin scattering () measurements have emerged in this field as a promising technology for lower noise and higher speed measurements. However, further improvements are fundamentally limited by constraints on the optical power level that can be used in biological samples, which effectively caps the gain and signal-to-noise ratio () of biological measurements. This limitation is compounded by practical limits on the optical probe power due to detector saturation thresholds. As a result, -based measurements in biological samples have provided minimal improvements (in noise and imaging speed) compared with spontaneous Brillouin microscopy, despite the potential advantages of the nonlinear scattering process. Here, we consider how a spectrometer can circumvent this fundamental trade-off in the low-gain regime by leveraging the polarization dependence of the interaction to effectively filter the signal from the background light via the polarization pulling effect. We present an analytic model of the polarization pulling detection scheme and describe the trade-space unique to Brillouin microscopy applications. We show that an optimized receiver design could provide >25× improvement in compared to a standard receiver in most typical experimental conditions. We then experimentally validate this model using optical fiber as a simplified test bed. With our experimental parameters, we find that the polarization pulling scheme provides 100× higher than a standard receiver, enabling 100× faster measurements in the low-gain regime. Finally, we discuss the potential for this proposed spectrometer design to benefit low-gain spectroscopy applications such as Brillouin microscopy by enabling pixel dwell times as short as 10 s.
布里渊光谱已成为绘制生物样品力学特性的重要工具。最近，受激布里渊散射（SBS）测量在该领域崭露头角，成为一种有望实现更低噪声和更高速度测量的技术。然而，进一步的改进从根本上受到可用于生物样品的光功率水平的限制，这有效地限制了生物测量的增益和信噪比（SNR）。由于探测器饱和阈值，光探测功率的实际限制加剧了这一局限性。因此，尽管非线性散射过程具有潜在优势，但与自发布里渊显微镜相比，基于SBS的生物样品测量在噪声和成像速度方面的改进微乎其微。在这里，我们考虑一种SBS光谱仪如何通过利用SBS相互作用的偏振依赖性，在低增益 regime中规避这种基本权衡，以通过偏振牵引效应有效地从背景光中滤除信号。我们提出了偏振牵引检测方案的解析模型，并描述了布里渊显微镜应用特有的权衡空间。我们表明，在大多数典型实验条件下，优化的接收器设计相比标准SBS接收器可使SNR提高>25倍。然后，我们使用光纤作为简化测试平台对该模型进行了实验验证。根据我们的实验参数，我们发现偏振牵引方案的SNR比标准SBS接收器高100倍，从而能够在低增益 regime中实现100倍更快的测量。最后，我们讨论了这种提议的光谱仪设计通过实现低至10 μs的像素驻留时间，对布里渊显微镜等低增益光谱应用产生益处的潜力。
