Temporal point-by-point arbitrary waveform synthesis beyond tera sample per second

Abstract Arbitrary waveform synthesizers play an essential role in modern information technology, yet electronic synthesizers face limitations due to the speed of analog-to-digital converters, typically in the range of tens to hundreds of giga samples per second (GSa/s). While photonic-assisted waveform synthesizers show promise in surpassing this ceiling, but the system reconfigurability remains a challenge. Here, we propose and demonstrate a temporal point-by-point arbitrary waveform synthesizer with a sampling rate beyond tera sample per second (TSa/s), leveraging an optical temporal Vernier caliper in the photonic synthetic dimension. The temporal Vernier caliper, consisting of a mode-locked laser (MLL) and a fiber loop, utilizes a slight detuning between the optical pulse period of the MLL and the round-trip time delay of the loop to control the sampling rate of a synthesized waveform with high flexibility. The amplitude of each sampling point is manipulated at a low speed corresponding to the reciprocal of the pulse period, thus massive point-by-point waveform synthesis can be achieved with full reconfigurability. In the experiment, arbitrary waveforms with widely tunable sampling rates from 5 GSa/s to 1 TSa/s are synthesized, which is an order of magnitude higher than state-of-the-art electronic counterparts. To show the capability of massive point-by-point synthesis, communication signals for high-speed wireless communications and linearly chirped microwave waveforms for high-resolution multi-target detection are synthesized. The capabilities of tunable sampling rate and massive point-by-point synthesis make the temporal Vernier caliper a universal solution for high-speed microwave sources, offering significant promise for broad applications requiring high-speed signal sources.