Four-wave mixing based spectral Talbot amplifier for programmable purification of optical frequency combs

Optical frequency combs (OFCs) with programmable free spectral range and high optical carrier-to-noise ratio (CNR) play a crucial role indiverse research fields, including telecommunications, spectroscopy, quantum information, astronomy, sensing, and imaging. Unfortunately,the presence of stochastic noise often results in degraded optical CNR, leading to limited communication performance and measurementaccuracy in comb-based systems. There is a lack of effective and flexible methods to improve the CNR of OFCs contaminated by broadbandnoise, hampering their widespread utilization. To address this challenge, we propose a four-wave mixing based spectral Talbot amplifier topurify OFCs flexibly. Our approach employs programmable spectral phase filters followed by a nonlinear Kerr medium to regenerate an OFCwith superior CNR. In our experimental demonstration, we regenerated a 165-GHz spaced CNR enhanced OFC from a noise-dominatedcomb source spaced at 11 GHz, achieving up to similar to 11-dB CNR improvement. The technique allows for a user-defined purification factormto range from 7 to 15. Furthermore, our scheme demonstrates flexibility in adjusting the wavelengths of the regenerated comb lines via atunable optical delay line without the need for a tunable seed laser. We also investigated the impact of the pump and signal on the regeneratedcomb experimentally and studied the influence of dispersion mismatch on the suppression of undesired sidebands numerically. Our proposedscheme presents a powerful alternative for programmable purification, manipulation, and detection of noise-dominated spectral waveforms.