Programmable photonic integrated circuits (PICs) are dense assemblies of tunable elements that provide flexible reconfigurability to enable different functions to be selected; however, due to manufacturing variations and thermal gradients that affect the optical phases of the elements, it is difficult to guarantee a stable correspondence between the electrical commands to the chip, and the function that it provides. Here we demonstrate a self-calibrating programmable PIC with full control over its complex impulse response, in the presence of thermal cross-talk between phase-tuning elements. Self-calibration is achieved by: (1) incorporating an optical reference path into the PIC; (2) using the Kramers–Kronig relationship to recover the phase response from amplitude measurements; and (3) applying a fast-converging self-calibration algorithm. We demonstrate dial-up signal processing functions with complex impulse responses using only 25 training iterations. This approach offers stable and accurate control of large-scale PICs, for demanding applications such as communications network reconfiguration, neuromorphic hardware accelerators and quantum computers.

可编程光子集成电路 (PIC) 是可调谐元件的密集组合，可提供灵活的可重构性，以便选择不同的功能；然而，由于影响元件光学相位的制造变化和热梯度，很难保证对芯片的电命令与其提供的功能之间的稳定对应。在这里，我们展示了一个自校准可编程 PIC，在相位调谐元件之间存在热串扰的情况下，它可以完全控制其复杂的脉冲响应。通过以下方式实现自校准： (1) 将光学参考路径合并到 PIC 中；(2) 使用 Kramers-Kronig 关系从幅度测量中恢复相位响应；(3) 应用快速收敛的自校准算法。我们仅使用 25 次训练迭代演示了具有复杂脉冲响应的拨号信号处理功能。这种方法为通信网络重新配置、神经形态硬件加速器和量子计算机等要求苛刻的应用提供了对大规模 PIC 的稳定和准确的控制。