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Packet-modulated communication may play a pivotal role in the future of short-range communications at terahertz (THz) frequencies. As with ultra-wideband communication, the advantageous of this type of communication are its extremely short duration, immunity to multipath fading, wide bandwidth and low power spectral density. However, due to the lack of a fast modulation method, packet-modulated pulse communication at THz frequencies has not yet been demonstrated. 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 hundred or more THz pulses in parallel with sub-picosecond accuracy and is versatile for various modulation protocols. Strikingly, the temporal resolution of our modulation scheme depends on geometric optics and not on a high-speed electronic device. Furthermore, the ability of STEs to generate quasi-continuous THz pulses offers an alternative solution to the photomixer, a key THz communication technology, and thus could lead to a promising new THz communication modality.

We demonstrate a new technique for the generation and the active modulation of a THz pulse train using the combination of a terahertz (THz) spintronic emitter with an echelon mirror and a digital micromirror device (DMD).

The generation and coding of multi-cycle terahertz (THz) pulses offers interesting possibilities, such as frequency comb spectroscopy or ultra-fast packet communication. In contrast to the radio-frequency (RF) 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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