Optical Hilbert Receiver With Field Recovery for Terabit Scale‐Across Data‐Center Interconnects

The explosive growth of generative artificial intelligence is driving an unprecedented demand for high‐speed optical interconnects in computing clusters. Spectrally‐efficient and cost‐effective direct detection receivers are urgently required in massively parallel data‐center interconnects. However, the phase information of the optical field is inherently lost during the square‐law detection of the photodiode, imposing stringent constraints in bandwidth and transmission distance for direct detection receivers. Here, we present an optical Hilbert receiver concept that enables full optical field recovery of complex‐valued double‐sideband signals in a direct detection manner without a local oscillator laser. The proposed receiver exhibits a flat transfer function without singularities at high frequencies, thereby maximizing its reception bandwidth. The all‐pass property minimizes the insertion loss and enhances its receiver sensitivity compared to optical filter‐based schemes. We design an iterative signal‐signal beating interference compensation algorithm to digitally linearize the reception. In addition, we experimentally demonstrate single‐wavelength and single‐polarization direct detection with a record line rate up of 1.03 Tb/s at a power efficiency of ∼ 18.8 fJ/bit. We further extend the transmission distance to 100 km standard single‐mode fiber to cover the inter‐data‐center scenario. The concept of an optical Hilbert receiver provides a scalable and cost‐effective solution for high‐speed optical interconnects.