The introduction of photonic technologies into mature electronic circuits is in high demand to accelerate on-chip information networking and even computing. Great difficulty lies in the fact that the optoelectronic coupling at their interfaces requires a substantial charging energy determined by their capacitance. Optoelectronic devices have been too large to reduce the integrated capacitance down to the femtofarad scale. Here we use a photonic-crystal platform to demonstrate the first experimental proof of optoelectronic integration at only 2 fF. This allows us to realize a record-low attojoule-energy electro-optic modulator (an electrical-to-optical or E–O converter) and an amplifier-free photoreceiver (an optical-to-electrical, or O–E converter), which leads to ultralow-energy signal conversion. By integrating these O–E/E–O devices, we demonstrate femtofarad ‘O–E–O transistors’ with optical signal gain that show various optical nonlinear functions, including as all-optical switches, wavelength converters and cascadable optical repeaters with a femtojoule-per-bit energy consumption. These femtofarad-scale O–E/E–O/O–E–O devices promise tightly coupled photonic–electronic integration for new fields of energy-saving information processing.

强烈要求将光子技术引入成熟的电子电路中，以加快片上信息网络乃至计算的速度。很大的困难在于以下事实：在它们的界面处的光电耦合需要由它们的电容确定的大量充电能量。光电器件太大，无法将集成电容减小到毫微微法拉规模。在这里，我们使用光子晶体平台来演示仅2 fF的光电子集成的第一个实验证明。这使我们能够实现创纪录的低焦耳能量电光调制器（电光或E-O转换器）和无放大器的光接收器（光电电或O-E转换器），导致超低能信号转换。通过集成这些O–E / E–O设备，我们演示了具有光信号增益的femtofarad'O-E-O晶体管'，它们显示了各种光学非线性功能，包括作为全光开关，波长转换器和级联的光中继器，每比特的能耗为毫微焦耳。这些毫微微法拉规模的O–E / E–O / O–E–O设备保证了光电子耦合紧密结合，可用于节能信息处理的新领域。