Terahertz passive amplification via the temporal Talbot effect in metamaterial-based Bragg fibers

A fully passive terahertz (THz) pulse amplification device is proposed based on leveraging the temporal Talbot effect (TTE) on a highly dispersive silicon-based metamaterial Bragg fiber. To maximize the TTE passive gain, we introduce and explore three different strategies, denoted as coherent pulse addition (CPA), forward Talbot illuminator (FTAI), and backward Talbot illuminator (BTAI). The BTAI strategy allows additional degrees of freedom for controlling the output pulse shape. Moreover, by using a continuous phase profile, we overcome the hurdle of implementing discrete phase gratings in limited time response phase modulators. We explore different pulse shapes and chirped pulses with CPA, and different gain factors with both BTAI and FTAI. Numerical simulation results show a 5.8 dB gain for a 9.8 cm long fiber with the CPA method, a 9.9 dB gain with FTAI (1.37 cm long), and a 8.8 dB gain with BTAI (1.25 cm long). These results indicate the potential of the approaches presented here, which can be used as a springboard for further developments toward high gain passive amplification THz devices. (C) 2022 Optica Publishing Group