Recently, intensity correlation measurements have been reported for the first time in the Terahertz range, where a time-domain version of a Hanbury Brown Twiss setup based on electro-optic sampling was employed. This technique proved its usefulness for fundamental studies of photon correlations of bunched (thermal) and Poissonian (coherent) light, but not only so. Also in practical applications, it has been employed to determine the temporal emission pattern of Terahertz Quantum Cascade Laser based Frequency Combs, which are very promising devices for future highly integrated spectrometers. The key parameter of this technique is its short temporal resolution. Up to date, the technique still does not provide the necessary sensitivity for exploring the yet vacuous regime of single photons in the terahertz. In this work we present our recent efforts for increasing the sensitivity of electro-optic sampling, by means of cryogenic cooling and novel organic materials for the Terahertz range. In particular, we present a novel device for collinear electro-optic detection, which features a high-aspect ratio antenna on a quartz substrate with a plasmonic gap filled by electro-optic molecules.
The quantum nature of photonic systems is reflected in the photon statistics of the light they emit. Therefore, the development of quantum optics tools with single photon sensitivity and excellent temporal resolution is paramount to the development of exotic sources, and is particularly challenging in the THz range where photon energies approach kbT at T=300 K. Here, we report on the first room temperature measurement of field g1(τ) and intensity correlations g2(τ) in the THz range with sub-cycle temporal resolution (146 fs) over the bandwidth 0.3-3 THz, based on electro-optic sampling. With this system, we are able to measure the photon statistics at threshold of a THz Quantum Cascade Laser.
A portable, stand-alone, real-time THz imaging system for high resolution is presented. The total weight of the apparatus
is less than 15 kg and its physical dimension is of approximately (65 cm)3. A quantum cascade laser emitting at 3.4 THz
based on a third-order distributed feedback cavity is used as radiation source for transmission and reflection imaging
modes. We report real-time THz imaging with a bolometric camera operating at 15 Hz producing movies with a
resolution of 120 x 160 pixels. With the help of a Stirling motor cryocooler the laser operates in continuous-wave at 40 K
with more than 1 mW output power and less than 300 mW of power consumption. We were able to image small objects
employing refractive elements that we manufactured in high density polyethylene achieving a resolution of twice the