We present a programmable silicon photonic integrated circuit (PIC) that can be configured to show nonlinear nonreciprocal transmission at high optical input power. Nonreciprocal transmission in PICs is of fundamental importance in various fields. Despite diverse approaches to generate nonreciprocal transmission, the research on efficient control of this effect is still scarce. The silicon PIC presented here has programmable linear and nonlinear behavior using integrated phase shifters. In the nonlinear regime (high optical power), the device can be configured to be either reciprocal or nonreciprocal between opposite propagation directions with over 30 dB extinction ratio and only 1.5 dB insertion loss. More importantly, the high/low transmission direction can be dynamically reconfigured. Furthermore, nonreciprocal transmission based on nonlinearities usually requires the optical field in both propagation directions to be high, in order to induce a large extinction ratio. For our circuit, only the forward-propagating light needs to have high power to enjoy low-loss transmission while the backward propagating light will always suffer a high rejection. Besides this nonreciprocal behavior, the circuit also offers the ability for all-optical functions, such as switching, optical compute gates, or optical flip-flops, thanks to its unique controllable nonlinear behavior. This work can trigger new research efforts in nonreciprocal photonics circuits.

中文翻译：

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硅光子集成电路中可重构的非线性不可逆传输

我们提出了一种可编程的硅光子集成电路（PIC），可以对其进行配置，以显示在高光输入功率下的非线性不可逆传输。PIC中的不可逆传输在各个领域都具有根本的重要性。尽管产生不可逆传播的方法多种多样，但仍然缺乏有效控制这种效应的研究。使用集成的移相器，此处介绍的硅PIC具有可编程的线性和非线性行为。在非线性状态（高光功率）下，该器件可以配置为在相对传播方向之间互逆或互逆，消光比超过30 dB，插入损耗仅为1.5 dB。更重要的是，可以动态地重新配置高/低传输方向。此外，基于非线性的不可逆传输通常要求在两个传播方向上的光场都较高，以便引起较大的消光比。对于我们的电路，只有前向传播的光需要具有高功率才能享受低损耗传输，而后向传播的光将始终遭受高抑制。除了这种不可逆的行为，由于其独特的可控制的非线性行为，该电路还具有全光学功能，例如开关，光学计算门或光学触发器。这项工作可以触发不可逆光子电路的新研究工作。只有前向传播的光需要具有高功率才能享受低损耗传输，而后向传播的光将始终遭受高抑制。除了这种不可逆的行为，由于其独特的可控制的非线性行为，该电路还具有全光学功能，例如开关，光学计算门或光学触发器。这项工作可以触发不可逆光子电路的新研究工作。只有前向传播的光需要具有高功率才能享受低损耗传输，而后向传播的光将始终遭受高抑制。除了这种不可逆的行为，由于其独特的可控制的非线性行为，该电路还具有全光学功能，例如开关，光学计算门或光学触发器。这项工作可以触发不可逆光子电路的新研究工作。