Nonlinear interferometers with correlated photons hold promise to advance optical characterization and metrology techniques by improving their performance and affordability. These interferometers offer subshot noise phase sensitivity and enable measurements in detection-challenging regions using inexpensive and efficient components. The sensitivity of nonlinear interferometers, defined by the ability to measure small shifts of interference fringes, can be significantly enhanced by using multiple nonlinear elements, or crystal superlattices. However, to date, experiments with more than two nonlinear elements have not been realized, thus hindering the potential of nonlinear interferometers. Here, we build a nonlinear interferometer with up to five nonlinear elements, referred to as superlattices, in a highly stable and versatile configuration. We study the modification of the interference pattern for different configurations of the superlattices and perform a proof-of-concept gas sensing experiment with enhanced sensitivity. Our approach offers a viable path towards broader adoption of nonlinear interferometers with correlated photons for imaging, interferometry, and spectroscopy.

中文翻译：

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晶体超晶格中的非线性干涉。

具有相关光子的非线性干涉仪有望通过改善其性能和可承受性来提高光学表征和计量技术。这些干涉仪可提供子脉冲噪声相位灵敏度，并能够使用廉价，高效的组件在具有挑战性的区域中进行测量。通过使用多个非线性元件或晶体超晶格，可以显着提高非线性干涉仪的灵敏度，该灵敏度由测量干涉条纹的小位移的能力定义。然而，迄今为止，尚未实现具有两个以上非线性元件的实验，因此阻碍了非线性干涉仪的潜力。在这里，我们以高度稳定和通用的配置构建了一个非线性干涉仪，该干涉仪具有多达五个非线性元素，称为超晶格。我们研究了针对不同构型的超晶格干涉图样的修改，并进行了具有增强灵敏度的概念验证气体传感实验。我们的方法为广泛采用带有相关光子的非线性干涉仪提供了一条可行的途径，用于成像，干涉测量和光谱学。