The generation and coding of multi-cycle terahertz (THz) pulses offer interesting possibilities, such as frequency comb spectroscopy or ultra-fast packet communication. In contrast to the radio frequency domain, which has largely exploited packet communication, this research area is almost unexplored at THz frequencies. Indeed, because of the lack of fast modulation and detection methods at THz frequencies, current developments often rely on hybrid techniques mixing photonics and ultrafast electronics. Here, we present a method for the generation and modulation of a coded THz pulse train. Our scheme is based on the combination of a spintronic THz emitter (STE) with an echelon mirror and a digital micromirror device. This highly scalable configuration is capable of modulating a hundred or more THz pulses in parallel with sub-picosecond accuracy. Strikingly, the temporal resolution of our modulation scheme depends on geometric optics and not on a high-speed electronic device. Furthermore, our scheme confirms the ability of STEs to generate quasi-continuous THz pulses and offers a new photonic solution on dynamic THz pulse train control.
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