|
Over the past decade, the performance of generation and detection schemes for short electromagnetic waveforms in the THz spectral range has been improved at a rapid pace and facilitated the exploration of novel quantum phenomena of solid-state systems. Here, we present a selection of recent key advances and discuss their impact on cutting-edge fundamental research. Widely tunable high-field sources providing atomically strong, phase-locked few-cycle lightwaves with field amplitudes of up to 1 V/A at few-kHz repetition rates have driven dynamical Bloch oscillations in bulk semiconductors, quasiparticle collisions, and control of the valley pseudo-spin in monolayer dichalchogenides. Novel, highly phase-stable sources operating at repetition rates of 190 kHz provide comparably strong fields of up to 13 MV/cm, foreshadowing future applications in ultrabroadband frequency-comb metrology or lightwave scanning tunneling microscopy. Similarly, electro-optic sensors have been pushed to the quantum level, detecting THz waveforms which contain only 0.1 photons, on average, enabling strongly subdiffractional and subcycle tomography of interface polaritons black phosphorus in THz near-field scattering experiments. Moreover, customized FPGA technology has enabled synchronous single-shot detection of incoherent THz electric fields with amplitudes of less than 0.5 V/cm. In combination with femtosecond fiber lasers and an acousto-optical delay line, we have implemented fast-scan THz time-domain spectroscopy with a waveform refresh rate of 36 kHz and a bandwidth of 3 THz. The acquisition time of only 28 µs and signal-to-noise ratio of 27 for a single waveform, or 1.7×10^5/√Hz, may power multidimensional spectroscopy or real-time monitoring of non-repeatable processes in technology or biology.
|
