发表机构
The University of Tokyo; RIKEN（东京大学; 理化学研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文利用种子光参量放大产生的孪生光束进行平衡探测，将中红外光热测量噪声抑制至散粒噪声以下5 dB，并在液态水测量中实现SNR增强超过2 dB，展示了亚散粒噪声MIP测量的可行性。
AI 中文摘要
中红外光热（MIP）测量利用可见光或近红外光探测由中红外（MIR）吸收引起的折射率变化，近年来已成为生命科学中MIR光谱成像的一种强大模态。降低测量噪声可以在不牺牲信噪比（SNR）的情况下降低探测功率，从而减轻样品损伤的风险。然而，即使在没有经典噪声的情况下，使用经典相干探针的传统MIP测量的SNR也从根本上受到散粒噪声的限制。在此，我们展示了利用通过种子光参量放大产生的孪生光束实现亚散粒噪声MIP测量。对孪生光束的平衡探测将噪声抑制到比使用相干光束建立的散粒噪声水平低5 dB以上。作为原理验证演示，我们使用平衡孪生光束探测测量了液态水的MIP信号，并实现了比平衡相干光束探测高2 dB以上的SNR增强。
英文摘要
Mid-infrared photothermal (MIP) measurement probes refractive-index changes induced by mid-infrared (MIR) absorption using visible or near-infrared light and has recently emerged as a powerful modality for MIR spectro-imaging in the life sciences. Reducing measurement noise allows the probe power to be lowered without compromising the signal-to-noise ratio (SNR), thereby mitigating the risk of sample damage. However, even in the absence of classical noise, the SNR of conventional MIP measurements using a classical coherent probe is fundamentally limited by shot noise. Here, we demonstrate sub-shot-noise MIP measurement using twin beams generated through seeded optical parametric amplification. Balanced detection of the twin beams suppresses the noise by more than 5 dB below the shot-noise level established using a coherent beam. As a proof-of-principle demonstration, we measure the MIP signal from liquid water using balanced twin-beam detection and achieve an SNR enhancement of more than 2 dB over the balanced coherent-beam detection.
