Abstract-Three‐dimensional printing technologies for terahertz applications: A review

Jingye Sun, Fangjing Hu,

https://onlinelibrary.wiley.com/doi/abs/10.1002/mmce.21983

Three‐dimensional (3D) printing technologies enables fast prototyping of complex 3D objects with ever improving printing qualities. To date, 3D printing has been found useful in areas such as manufacturing, industrial design, aerospace, dental and medical industries, and many others. In this article, we review recent advances of 3D printing technologies for terahertz (THz) applications. Different 3D printing technologies and printable materials are first discussed and compared. 3D‐printed THz components and devices, which are categorized as waveguides/fibers, antennas, and quasi‐optical components, are further demonstrated. It is found that the performances and functionalities of 3D‐printed THz devices have been greatly enhanced, while the operating frequencies have been increased from the lower end of THz range to over 1 THz region. With further development of novel materials and printing techniques, it is believed that 3D printing technologies will play an important role in the realization of THz components for efficient control and manipulation of THz waves.

Scientists 3D Print an Effective Terahertz Waveguide

(a) Segments of the hollow waveguide; (b) experimental results of the loss coefficient; (c) mechanical spliced 90 cm hollow waveguide.

https://3dprint.com/229232/scientists-3d-print-effective-terahertz-waveguide/

The terahertz (THz) wave is the electromagnetic radiation at frequencies from 0.1 to 10 THz, which is located between the millimeter wave and the far infrared wave. It has not been fully studied because of a lack of effective means of generation, detection and transmission, so it is referred to as the “Terahertz Gap.” The terahertz wave has a lot of potential in non-destructive imaging, biomedicine and national security and defense, because it has penetrability for most of non-polar materials and does not cause ionization damage while covering the vibration and rotational energy levels of biological macromolecules.

In a paper entitled “A 0.1 THz low-loss 3D printed hollow waveguide,” a group of researchers discusses the use of 3D printing to create THz functional devices, such as terahertz lenses, phase plates, waveguides and more. 3D printing is a low-cost, simple and effective way to create these devices, they point out.

“Therefore, the combination of low-loss dielectric waveguide and low-cost 3D printing will help to break through the bottlenecks and realize THz remote applications,” the researchers state. “The paper focuses on the design, fabrication, and characterization of a novel 0.1 THz low-loss hollow waveguide. Its theoretical loss is as low as 0.009 cm−1 and the measured loss is 0.015 cm−1. The experimental results show that the proposed hollow waveguide not only reduces the transmission loss of the terahertz wave, but also can effectively localize the terahertz field and confine the divergence angle of the terahertz beam.”

The researchers used PLA to create the hollow waveguide. First they needed to 3D print a PLA disk in order to obtain the elecrtromagnetic parameters of the material. The disk was printed on an Ultimaker 3D printer and characterized by terahertz time-domain spectroscopy (THz-TDS).

“After that the design for the hollow waveguide could be started,” the researchers continue. The first step is designing the cross section of the waveguide based on the anti-resonant waveguide model and drawing the cross section’s two-dimensional graph. Secondly, the graph is imported into the finite element simulation software (Comsol Multiphysics) and a larger circle around the cross section is drawn as the perfect matching layer. Thirdly, the different materials and the corresponding refractive index are selected and the design model is meshed. Finally, according to the simulation, the effective refractive index of different modes transmitted in the center air hole of the hollow waveguide can be acquired.”

(a) Cross section of the hollow waveguide; (b) HE11 fundamental mode field distribution

The 90-cm-long hollow waveguide was then 3D printed and characterized. To verify the localization effect of the hollow waveguide on THz wave, the researchers measured the THz divergence angle at the end of the waveguide. The measured loss was 0.015 cm−1. The experimental results showed that the hollow waveguide can not only reduce the transmission loss of the terahertz wave in the air, but also effectively localize the terahertz wave. The researchers conclude that remote low-cost THz sensing and imaging can be achieved in the future by the development of flexible and longer hollow waveguides.

Authors of the paper include Pengfei Qi, Weiwei Liu and Cheng Gong.

Abstract-Complex Dielectric Permittivity of Engineering and 3D-Printing Polymers at Q-Band

  Francisco Casado,Nicolás Reyes,Valeria Tapia, Claudio Jarufe, Ricardo Finger, Leonardo Bronfman

https://link.springer.com/article/10.1007/s10762-018-0528-9

We report experimental values of the complex dielectric permittivity of a wide variety of engineering polymers. Measurements were done using the filling waveguide method at Q-band (30–50 GHz), being representative of the values over the millimeter wave regime. This method has a high accuracy, providing excellent wide-bandwidth characterization. Measured samples include the most common engineering materials as polyamide, polyethylene, polytetrafluoroethylene, polyoxymethylene, polylactic acid, phenol formaldehyde resin, polypropylene, polyvinyl chloride, acrylonitrile butadiene styrene, polyphenyle sulfide, and polyether ether ketone. Results are comprehensive and represent an important contribution to the technical literature which lacks of material measurements at these frequencies. Of particular interest are samples of 3D printed materials and high performance polymers, that will probably find new and novel applications in the field of microwave components and antennas for the millimeter wave band.

Abstract-3-D Printed Anti-Reflection Structures for the Terahertz Region

Jarosław Bomba, Jarosław Suszek, Michał Makowski, Artur Sobczyk, Maciej Sypek

https://link.springer.com/article/10.1007%2Fs10762-017-0435-5


Terahertz radiation has a growing number of applications in material characterization, where spectral fingerprinting and diffractive effects are the carriers of information. On the other hand, electromagnetic waves in the range of millimeters exhibit strong unwanted specular reflections, resulting in uncontrolled interferences. This problem is especially disturbing in the goniometric time-domain spectroscopy (TDS) configuration, where angular distribution of the field modified by the sample is altered by unwanted reflections. For this reason, low-cost anti-reflection layers are desired. Here, we present a simple way of designing and manufacturing one-sided and two-sided anti-reflection polyamide layers for the THz range. The structures were fabricated using 3-D printers based on selective laser sintering. We demonstrate experimentally in the goniometric time-domain spectroscopy the significant reduction of wavelength-dependent oscillations in Fabry-Perot configuration in the range between 0.1 and 0.3 THz. We also examine the influence of the anti-reflection layers on the distribution of THz energy in reflected, transmitted, and diffracted fields.

Abstract-Channel Multiplexing in Wireless Terahertz Communications Using Orbital Angular Momentum States

Kathirvel Nallappan, Hichem Guerboukha, Mohamed Seghilani, José Azana, Chahé Nerguizian, Maksim Skorobogatiy

(Submitted on 26 Aug 2017)

https://arxiv.org/abs/1708.08005

We present design and experimental validation of the system for the generation of the Orbital Angular Momentum (OAM) states using 3D-printed low-loss metamaterial phase plates for application in the terahertz (THz) wireless communications. By azimuthally varying the hole pattern density within the phase plate, the local effective refractive index is varied, thus also changing the local propagation constant in the azimuthal direction. The OAM of any topological charge can be created by simply varying the thickness of the phase plate. The phase plate with topological charge (m=1) is 3D printed and the amplitude and the phase of the terahertz signal after passing the plate is characterized using the THz-time domain imaging system. Finally, we present the experimental setup and theoretical simulation on the multiplexing and de-multiplexing of several different OAM states for applications in wireless terahertz communication.

Abstract-Hybrid 3-D Printing Technology for Tunable THz Applications

William J. Otter,  Stepan Lucyszyn,

http://ieeexplore.ieee.org/document/7797186/

In recent years, additive manufacturing has experienced rapid growth, due to its inherent capabilities for creating arbitrary 3-D structures, accessibility, and associated low manufacturing costs. This paper first reviews the state of the art in 3-D printing for terahertz (THz) applications and identifies the critical features required for such applications. The future potential for this technology is demonstrated experimentally with the first 3-D-printed, optically controlled THz IQ vector modulator. Here, miniature high-resistivity silicon implants are integrated into metal-pipe rectangular waveguides. The 3-D-printed split-block assembly also houses two packaged infrared laser diodes and a heat sink. The measured performance of a proof-of-principle 4-quaternary amplitude modulation (4-QAM) vector modulator that operates up to 500 GHz is reported. This new hybrid 3-D printing THz technology, which combines semiconductor devices with potentially low-cost, high-performance passive guided-wave structures represents a paradigm shift and may prove to be an ideal solution for implementing affordable transceivers in future ubiquitous THz applications.

Abstract-Quasi-Wollaston-Prism for Terahertz Frequencies Fabricated by 3D Printing

• A. I. Hernandez-Serrano, 
• E. Castro-Camus
• • 
    

http://link.springer.com/article/10.1007/s10762-016-0350-1

In this letter, we present the design, fabrication, and characterization of a quasi-Wollaston prism for terahertz frequencies based on form birefringence. The prism uses the birefringence induced in a sub-wavelength layered plastic-air structure that produces refraction in different directions for different polarizations. The component was simulated using the finite-difference-time-domain method, fabricated by 3D printing and subsequently tested by terahertz time-domain spectroscopy showing a polarization separation around of 23° for frequencies below 400 GHz, exhibiting cross polarization power extinction ratios better than 1.6 × 10−3 at 200 GHz.

Abstract-F Electromagnetic and thermal properties of three-dimensional printed multilayered nano-carbon/poly(lactic) acid structures

A. Paddubskaya1,2, N. Valynets1, P. Kuzhir1,3,a), K. Batrakov1, S. Maksimenko1,3, R. Kotsilkova4, H. Velichkova4, I. Petrova4, I. Biró5,b),K. Kertész6,c), G. I. Márk6,c), Z. E. Horváth6,c) and L. P. Biró6,c)


a) Author to whom correspondence should be addressed. Electronic mail: polina.kuzhir@gmail.com. Tel.: +375 17 200 7410.
b) URL: http://3dkivansag.blog.hu/
c) URL: http://www.nanotechnology.h
http://scitation.aip.org/content/aip/journal/jap/119/13/10.1063/1.4945576?TRACK=RSS

A new type of light-weight material produced by 3D printing consisting of nano-carbon doped polymer layer followed by a dielectric polymer layer is proposed. We performed temperature dependent characterization and measured the electromagnetic (EM) response of the samples in the GHz and THz range. The temperature dependent structuralcharacteristics, crystallization, and melting were observed to be strongly affected by the presence and the number of nano-carbon doped layers in the sandwich structure. The electromagnetic measurements show a great potential of such a type of periodic materialfor electromagnetic compatibility applications in microwave frequency range. Sandwich structurescontaining only two nano-carbon layers already become not transparent to the microwaves, giving an electromagnetic interference shielding efficiency at the level of 8–15 dB. A sandwich consisting of one nano-carbon doped and one polymer layer is opaque for THz radiation, because of 80% of absorption. These studies serve as a basis for design and realization of specific optimal geometries of meta-surface type with the 3D printing technique, in order to reach a high level of electromagnetic interference shielding performance for real world EM cloaking and EM ecology applications.