Terahertz photonic single‐pole double‐throw (SPDT) switches, which facilitate on‐chip channel control and signal routing, serve as the key components of future terahertz communication and sensing systems. However, broadband and low‐loss on‐chip photonic SPDT switches still present a formidable challenge due to the restricted capability of manipulating terahertz waves in photonic circuits. Here, a non‐Hermitian loss‐driven solution is proposed for achieving broadband and low‐loss terahertz on‐chip photonic SPDT switches. As proof of concept, an all‐silicon terahertz SPDT switching chip is experimentally demonstrated around the center frequency of 125 GHz with a relative bandwidth of 7.2%. The two paths are driven by external optical pumping and evolve adiabatically around an exceptional point (EP) in the unbroken and broken PT‐symmetric phases. Interestingly, the strong non‐Hermitian loss instead enforces the photonic modes to the low‐loss energy level and thereby keeps the switch working at the low‐loss transmission status. As a result, the minimum optical powers require for the ultrafast terahertz communications are only −2 and 1 dBm. Both channels of the SPDT switch support on‐chip 16‐QAM streams with a 36‐Gbit s−1 data rate. The design as a basic building block is anticipated for a myriad of on‐chip applications, including 6G communications, detection, and sensing.

中文翻译：

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非厄米特损耗驱动宽带低损耗片上太赫兹光子 SPDT 开关


太赫兹光子单刀双掷 （SPDT） 开关有助于片上通道控制和信号路由，是未来太赫兹通信和传感系统的关键组件。然而，由于在光子电路中操纵太赫兹波的能力有限，宽带和低损耗片上光子 SPDT 开关仍然面临艰巨的挑战。这里提出了一种非厄米特损耗驱动解决方案，用于实现宽带和低损耗太赫兹片上光子 SPDT 开关。作为概念验证，在 125 GHz 的中心频率和 7.2% 的相对带宽附近对全硅太赫兹 SPDT 开关芯片进行了实验演示。两条路径由外部光泵浦驱动，并在未中断和断开的 PT 对称相中围绕一个异常点 （EP） 绝热演变。有趣的是，强非厄米特损耗反而将光子模式强制到低损耗能级，从而使开关工作在低损耗传输状态。因此，超快太赫兹通信所需的最小光功率仅为 −2 和 1 dBm。SPDT 开关的两个通道都支持具有 36 Gbit s-1 数据速率的片上 16-QAM 流。该设计作为基本构建块，有望用于无数片上应用，包括 6G 通信、检测和传感。