Due to their specific physical properties, HgCdTe-based heterostructures are expected to play an important role in terahertz photonic systems. Here, focusing on gated devices presenting inverted band ordering, we evidence an enhancement of the terahertz photoconductive response close to the charge neutrality point and at the magnetic field driven topological phase transition. We also show the ability of these heterostructures to be used as terahertz imagers. Regarding terahertz emitters, we present results on stimulated emission of HgCdTe heterostructures in their conventional semiconductor state above 30 THz, discussing the physical mechanisms involved and promising routes towards the 5–15 THz frequency domain.

Advanced THz setups require high performance optical elements with large numerical apertures and small focal lengths. This is due to the high absorption of humid air and relatively low efficiency of commercially available detectors. Here, we propose a new type of double-sided sub-THz diffractive optical element with suppressed geometrical aberration for narrowband applications (0.3 THz). One side of the element is designed as thin structure in non-paraxial approach which is the exact method, but only for ideally flat elements. The second side will compensate phase distribution differences between ideal thin structure and real volume one. The computer-aided optimization algorithm is performed to design an additional phase distribution of correcting layer assuming volume designing of the first side of the element. The experimental evaluation of the proposed diffractive component created by 3D printing technique shows almost two times larger performance in comparison with uncorrected basic diffractive lens.

We report on THz emission from HgCdTe bulk films. Our experiments clearly show magnetically tunable THz emission that can be attributed to electron radiative recombination between the Landau levels (cyclotron emission). Energy band structure theoretical calculations using Kane Hamiltonian are performed. They allow identification of observed resonances as related to transitions between two lowest conduction band Landau levels.

We report on the first THz magnetospectroscopy of double HgTe quantum well in magnetic fields up to 16 T. Very recently, specific metal phase, which holds some properties of natural bilayer graphene, was predicted in this system. In this work, we focus on the double HgTe QW with parameters, corresponding to such `bilayer graphene' phase. In our experiments we clearly observe THz optical transitions from double-degenerated zero-mode Landau level. A good agreement between experimental and theoretical transition energies confirms previous prediction of `bilayer graphene' phase in double HgTe quantum wells.

Demand for efficient terahertz (THz) radiation detectors resulted in intensive study of the asymmetric carbon nanostructures as a possible solution for that problem. In this work, we systematically investigate the response of asymmetric carbon nanodevices to sub-terahertz radiation using different sensing elements: from dense carbon nanotube (CNT) network to individual CNT. We conclude that the detectors based on individual CNTs both semiconducting and quasi-metallic demonstrate much stronger response in sub-THz region than detectors based on disordered CNT networks at room temperature. We also demonstrate the possibility of using asymmetric detectors based on CNT for imaging in the THz range at room temperature. Further optimization of the device configuration may result in appearance of novel terahertz radiation detectors.

We device plasmonic, bolometric and thermoelectric antenna-coupled Terahertz photodetectors based on black phosphorus and hybrid van der Walls heterostructures, showing 20000 signal to noise ratios and 100pW/Hz1/2 noise equivalent powers in the 0.3-3 THz frequency range.

Recent developments of THz detector arrays based on plasma wave field effect transistors are presented. By simultaneous development of the transistor arrays with their read-out circuits and diffractive 3D printed optics we demonstrate systems for imaging in 300 GHz atmospheric window with cameras or fast linear scanner. The first high speed THz postal scanner developed for real time fast A4 envelopes security screening is presented.