80 Gb/s PAM4 Signal Generation Based on Optical Time-Domain Interleaving Driven by Low-Frequency Electronics

A novel optical time-domain interleaving microwave photonic waveform synthesis method driven by low-frequency electronics is proposed and experimentally demonstrated, enabling the generation of various arbitrary waveforms, including NRZ-PAM4, RZ-PAM4, triangular, rectangular, sawtooth, and Gaussian waveforms. By mapping wavelength to temporal dimensions, an eight-channel system based on wavelength-division multiplexing (WDM) is constructed, enabling multiplexing and amplitude control of multi-wavelength optical signals. By exploiting the group velocity dispersion (GVD) of the fiber to achieve controllable relative delays, equally spaced pulse sequences are formed in the time-domain. Furthermore, the weighted superposition of waveforms is realized through the joint control of pulse delay and amplitude. By introducing a non-negative least squares (NNLS) optimization method to solve for the pulse weights, high-fidelity reconstruction of the target waveform is achieved. Simulation results show that the generated NRZ-PAM4 signal achieves a maximum data rate of 80 Gb/s, and the equivalent sampling rate of the arbitrary waveforms reaches 247.64 GSa/s and maintains good performance at 37.14 GSa/s and 92.86 GSa/s, the root mean square error (RMSE) of the generated waveforms is as low as 0.0498, confirming a good fidelity. This method provides a simple and effective solution for achieving high-speed, high-sampling-rate, and reconfigurable photonic arbitrary waveform generation.