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，由于光子电路中纵太赫兹波的能力有限，宽带和低损耗片上光子 SPDT 开关仍然面临巨大挑战。在这里，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，并围绕未中断和断开的 PT 对称相位中的异常点 （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 交换机的两个通道都支持数据速率为 36 Gbit 的 ⁻¹ 片上 16-QAM 流。该设计作为基本构建块，有望用于无数的片上应用，包括 6G 通信、检测和传感。