标题： 级联模式干涉仪：光谱形状和线宽工程 显示英文标题

标题： Cascaded-mode interferometers: spectral shape and linewidth engineering

摘要： 干涉仪是测量和塑造光场的重要工具，在光学计量、传感、激光物理和量子力学中被广泛应用。它们将具有相互相位延迟的波叠加，从而导致光强的变化。然后，频率相关的相位延迟允许塑造光的光谱，这对于滤波、路由、波形塑造或复用至关重要。简单的马赫-曾德尔干涉仪叠加空间波，通常产生依赖于频率的正弦输出强度，限制了光谱工程的能力。在此，我们提出了一种新框架，利用单个多模波导中的多个横向模式的干涉，在紧凑几何结构中实现任意光谱形状。通过设计刻蚀光栅，这些模式相互耦合，允许能量交换，类似于分束器，便于处理多个模式。我们从理论上和实验上展示了具有独立可调自由光谱范围和线宽的窄线宽光谱，以及各种横向模式的独立光谱形状。我们的方法可以应用于不同阶数、偏振和角动量的正交光模式，并在传感、光学计量、校准和计算方面具有前景。 显示英文摘要

摘要： Interferometers are essential tools to measure and shape optical fields, and are widely used in optical metrology, sensing, laser physics, and quantum mechanics. They superimpose waves with a mutual phase delay, resulting in a change in light intensity. A frequency-dependent phase delay then allows to shape the spectrum of light, which is essential for filtering, routing, wave shaping, or multiplexing. Simple Mach-Zehnder interferometers superimpose spatial waves and typically generate an output intensity that depends sinusoidally on frequency, limiting the capabilities for spectral engineering. Here, we present a novel framework that uses the interference of multiple transverse modes in a single multimode waveguide to achieve arbitrary spectral shapes in a compact geometry. Through the design of corrugated gratings, these modes couple to each other, allowing the exchange of energy similar to a beam splitter, facilitating easy handling of multiple modes. We theoretically and experimentally demonstrate narrow-linewidth spectra with independently tunable free spectral range and linewidth, as well as independent spectral shapes for various transverse modes. Our methodology can be applied to orthogonal optical modes of different orders, polarization, and angular momentum, and holds promise for sensing, optical metrology, calibration, and computing.