Geometrical Aberration Suppression for Large Aperture Sub-THz Lenses

Abstract

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.

Terahertz Diffractive Optics—Smart Control over Radiation

“…Knowing them, during simulation, the performance of the designed structure can be verified, assuming real illumination conditions, and can be corrected according to needs [24]. Sometimes, it is even necessary to introduce a correcting layer helping to obtain larger diffraction efficiency due to suppressing the influence of the material thickness even by a thin DOE [100].…”

Designing and manufacturing aspherical polystyrene lenses for the terahertz region

“…The widespread introduction of 3D printing additive technologies, including the method of fused deposition modeling (FDM), allows creating THz optics elements for scientific and technical applications [1][2][3][4].…”

“…The present-day technological development in the THz range opens new areas of applications in different domains, namely: medicine, security, food control, etc. These technologies continue their advance mainly in terms of detectors and sources [1][2][3]. Also, one of the important tasks in THz instrumentation development is to improve quasi-optic elements for various active THz vision systems.…”

3D Printed Terahertz Focusing Grating Couplers

“…Actually, there are notable developments in waveguides [2,3], lenses [4,5], demultiplexers [6] and gratings [7,8] among other devices developed for THz radiation that demonstrate the feasibility of THz communications. Although there are promising results, there is still a need to further explore THz technologies to achieve a similar performance as in microwave and optical technologies.…”