We propose and demonstrate a rectangular optical lattice filter with reconfigurable bandwidth and wavelength. The proposed reconfigurable rectangular lattice filter consists of three-stage cascaded ring-assisted Mach-Zehnder interferometers (RAMZIs), and each RAMZI unit serves as an approximate optical elliptical filter with optimized shape factor. The scheme and design principle are presented with the method of zero-pole theory. As a proof of concept, the proposed structure is fabricated on the Si$_3$ N$_4$ waveguide platform. In the experiment, the 3-dB bandwidth of the proposed filter can be continuously tuned from 14.1 GHz to 4.1 GHz, maintaining a rectangular transmission response, and the wavelength can also be continuously tuned. This reconfigurable rectangular optical lattice filter shows the potential in many practical applications for reconfigurable optical signal processing due to flexibility and reconfigurability.

中文翻译：

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具有连续可调带宽和波长的可重构矩形滤波器

我们提出并演示了一种具有可重构带宽和波长的矩形光学点阵滤波器。所提出的可重构矩形晶格滤波器由三级级联环辅助马赫-曾德干涉仪 (RAMZI) 组成，每个 RAMZI 单元用作具有优化形状因子的近似光学椭圆滤波器。采用零极点理论方法提出方案和设计原理。作为概念证明，所提出的结构是在 Si 上制造的$_3$ N$_4$波导平台。在实验中，所提出的滤波器的 3-dB 带宽可以从 14.1 GHz 到 4.1 GHz 连续调谐，保持矩形传输响应，并且波长也可以连续调谐。由于灵活性和可重构性，这种可重构矩形光学点阵滤波器在可重构光信号处理的许多实际应用中显示出潜力。