A. Tomasino, R. Piccoli, Y. Jestin, S. Delprat1, M. Chaker, M. Peccianti, M. Clerici4, A. Busacca, L. Razzari, R. Morandotti,
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| FIG. 1.3D sketch of the deep sub-λ slit (G) device embedded in a thin layer (T) of SiN, deposited on a quartz substrate. L and W are the length and the width of the metal pads, respectively. |
https://aip.scitation.org/doi/abs/10.1063/1.5052628
We present a novel class of CMOS-compatible devices aimed to perform the solid-state-biased coherent detection of ultrashort terahertz pulses, i.e., featuring a gap-free bandwidth at least two decades-wide. Such a structure relies on a 1-µm-wide slit aperture located between two parallel aluminum pads, embedded in a 1-µm-thick layer of silicon nitride, and deposited on a quartz substrate. We show that this device can detect ultra-broadband terahertz pulses by employing unprecedented low optical probe energies of only a few tens of nanojoules. This is due to the more than one order of magnitude higher nonlinear coefficient of silicon nitride with respect to silica, the nonlinear material employed in the previous generations. In addition, due to the reduced distance between the aluminum pads, very high static electric fields can be generated within the slit by applying extremely low external bias voltages (in the order of few tens of volts), which strongly enhance the dynamic range of the detected THz waveforms. These results pave the way to the integration of solid-state ultra-broadband detection in compact and miniaturized terahertz systems fed by high repetition-rate laser oscillators and low-noise, low-voltage generators.
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