单次相干过程层析与基于未探测光子的中红外偏振测量
Single-shot coherent process tomography and mid-infrared polarimetry with undetected photons
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中文总结 AI 辅助
提出折叠非线性干涉仪方案，利用频率复用实现单帧未探测光子相干过程层析，重建全部琼斯参数，并实现中红外偏振测量与偏振敏感OCT。
中文摘要 AI 辅助
基于未探测光子的测量通过推断从未被探测的探测光束的性质，将中红外信息转移到硅基友好波长上。迄今为止，该范式下的层析成像依赖于切换设置或扫描相位，并参照易受漂移影响的测量序列；尚无协议能从单帧中读取所有琼斯参数。我们证明，采用对角泵浦交叉晶体源的光折叠非线性干涉仪可在单个光谱仪帧内对未探测光束执行相干过程层析：它重建了光束往返琼斯矩阵的所有七个参数，即信道的相干部分。双折射群延迟走离通常被视为校准干扰，在此充当频率复用器：每个琼斯矩阵元素被分配其自身的载波，即与探测器端口配对的频谱条纹周期。由于复用利用了向下转换带宽而非仅仅容忍它，对每个探测器迹线进行一次傅里叶变换即可在该带宽内返回所有四个模量和所有三个相对相位，即完整的往返琼斯谱（直至全局相位），无需扫描或设置更改（一次性参考帧之后）。同时性使每个相对相位免受共模漂移影响，而暗载波（幺正性迫使其消失的自干涉项）提供了内置零检验。对于周期性极化KTP源的实际参数，该方案在硅相机上实现了3.5-4.2微米范围内波长分辨的中红外偏振测量（每个琼斯元素约80个光谱点），并扩展到深度分辨琼斯矩阵，即基于未探测光子的偏振敏感光学相干层析。费舍尔信息分析（据我们所知，这是未探测光子层析中的首次）设定了精度预算，并在相等光子数下将延迟复用与顺序协议进行了比较。
英文摘要
Measurements with undetected photons infer properties of a probe beam that is never detected, transferring mid-infrared information onto silicon-friendly wavelengths. Tomography in this paradigm has so far relied on switched settings or scanned phases, referenced across a drift-sensitive campaign; no protocol reads all Jones parameters from one frame. We show that a folded nonlinear interferometer with a diagonally pumped crossed-crystal source performs coherent process tomography of the undetected beam in a single spectrometer frame: it reconstructs all seven parameters of the beam's round-trip Jones matrix, the coherent part of the channel. Birefringent group-delay walk-off, normally a calibration nuisance, acts as a frequency multiplexer: each Jones-matrix element is assigned its own carrier, a spectral fringe period paired with a detector port. Because the multiplexing exploits the down-conversion bandwidth rather than merely tolerating it, a single Fourier transform per detector trace returns all four moduli and all three relative phases across that bandwidth, i.e., the full round-trip Jones spectrum up to a global phase, with no scan or setting change (after a one-time reference frame). Simultaneity makes every relative phase immune to common-mode drift, and a dark carrier, a self-interference term that unitarity forces to vanish, provides a built-in null test. For realistic parameters of a periodically poled KTP source the scheme yields wavelength-resolved mid-infrared polarimetry across 3.5-4.2 microns (~80 spectral points per Jones element) on a silicon camera, extending to depth-resolved Jones matrices, i.e., polarization-sensitive optical coherence tomography with undetected photons. A Fisher-information analysis, the first we are aware of in undetected-photon tomography, sets the precision budget and compares delay multiplexing to sequential protocols at equal photon number.
发表机构
- Humboldt-Universität zu Berlin（柏林洪堡大学）
- University of Science and Technology of China（中国科学技术大学）
- Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik（费迪南德·布劳恩研究所，莱布尼茨高频技术研究所）
机构由 AI 辅助整理，请以论文原文为准。
