Lu Jinsheng, Benea-Chelmus Ileana-Cristina, Ginis Vincent, Ossiander Marcus, Capasso Federico
Harvard John A. Paulson School of Engineering and Applied Sciences, 9 Oxford Street, Cambridge, MA 02138, USA.
Hybrid Photonics Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Sci Adv. 2025 Mar 21;11(12):eadt4154. doi: 10.1126/sciadv.adt4154. Epub 2025 Mar 19.
Interferometers are essential tools for measuring and shaping optical fields, widely used in optical metrology, sensing, laser physics, and quantum mechanics. They superimpose waves with a mutual phase delay, modifying light intensity. A frequency-dependent phase delay enables spectral shaping for filtering, routing, wave shaping, or multiplexing. Conventional Mach-Zehnder interferometers generate sinusoidal output intensities, limiting spectral engineering capabilities. Here, we propose a framework that uses interference of multiple transverse modes within a single multimode waveguide to achieve arbitrary spectral shapes in a compact geometry. Designed corrugated gratings couple these modes, enabling energy exchange akin to a beam splitter for easy multimode handling. We theoretically and experimentally demonstrate spectra with independently tunable linewidth and free spectral range, along with distinct spectral shapes for various transverse modes. Our method applies to orthogonal modes of different orders, polarization, and angular momentum, offering potential for sensing, calibration, metrology, and computing.
干涉仪是用于测量和塑造光场的重要工具，广泛应用于光学计量、传感、激光物理和量子力学领域。它们将具有相互相位延迟的波叠加在一起，从而改变光强。频率相关的相位延迟可实现用于滤波、路由、波形整形或复用的光谱整形。传统的马赫曾德尔干涉仪会产生正弦输出强度，限制了光谱工程能力。在此，我们提出了一个框架，该框架利用单个多模波导内多个横向模式的干涉，在紧凑的几何结构中实现任意光谱形状。设计的波纹光栅耦合这些模式，实现类似于分束器的能量交换，便于进行多模处理。我们在理论和实验上证明了具有独立可调线宽和自由光谱范围的光谱，以及各种横向模式的独特光谱形状。我们的方法适用于不同阶次、偏振和角动量的正交模式，为传感、校准、计量和计算提供了潜力。
