Abstract-Terahertz atmospheric propagation studies in support of wireless remote sensing

John F. O'Hara, Daniel R. Grischkowsky,

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10657/106570W/Terahertz-atmospheric-propagation-studies-in-support-of-wireless-remote-sensing/10.1117/12.2305019.short?SSO=1

Next generation sensors will all share in common the requirement to move increasingly massive amounts of data. As such, an infrastructure problem becomes apparent. Even if instruments can produce quality data, it is not necessarily feasible to collect and move it. With the rapidly growing number of sensors, basic data movement becomes an integral system-engineering problem. Wireless networks are being increasingly employed as part of that infrastructure, but may be rapidly overwhelmed, particularly in currently regulated frequency bands. These facts compel the development of terahertz wireless systems, which if implemented correctly could support the massive flow of `cloud', IoT, and distributed data. While such terahertz systems are continually growing closer to practical reality, they are still very immature. From a system-engineering perspective, it is apparent that there are even many fundamental gaps in knowledge that prevent reliable operations. Indeed, terahertz absorption through the atmosphere is still not fully understood, nor even correctly tabulated in some cases. We present new studies on terahertz propagation using comparisons to previous data and the international standards that commonly underpin system-level engineering of wireless systems. In particular, we examine the role of continuum absorption and high frequency absorption wings, and the method by which they are accounted for in engineering standards between 0-1 THz. These studies reveal a need for greater accuracy in atmospheric measurements.

Abstract-All-Dielectric Meta-lens Designed for Photoconductive Terahertz Antennas

 Qing Yu,  Jianqiang Gu, Quanlong Yang,  Ying Zhang,   Yanfeng Li, Zhen Tian, Chunmei Ouyang,   Jiaguang Han, John F. O'Hara, Weili Zhang

Impact Statement:

In this numerical study, we present a metasurface based lens directly integrated to a terahertz PCA transmitter which is rarely reported. Because its all-dielectric nature, the meta-lens not only offers an excellent collimation function, but also has a better transmittance efficiency than the traditional Si hyper-semispheric lens and most metal based terahertz meta-lenses. The meta-lens proposed here have promising applications in next-generation terahertz imaging and spectroscopy techniques.

Abstract:

We present an all-dielectric meta-lens designed to collimate terahertz waves emitted from a terahertz antenna. The meta-lens is not only thinner than a conventional bulk silicon lens, but also promises to eliminate the use of parabolic mirrors in a terahertz time-domain spectroscopy system. A systematic numerical study reveals that the meta-lens exhibits excellent performance in both the emitter and detector modules, converting between the spherical wave of the antennas and the collimated beam. The frequency and alignment dependences of the meta-lens are also investigated to comprehensively map its response characteristics. The all-dielectric meta-lens presented here may pave a way in developing high-performance integrated photoconductive terahertz antenna components.

Abstract-Tailoring terahertz plasmons with silver nanorod arrays

Wei Cao, Chunyuan Song, Thomas E. Lanier, Ranjan Singh, John F. O'Hara, William M. Dennis, Yiping Zhao & Weili Zhang

• http://www.nature.com/srep/2013/130503/srep01766/full/srep01766.html

Plasmonic materials that strongly interact with light are ideal candidates for designing subwavelength photonic devices. We report on direct coupling of terahertz waves in metallic nanorods by observing the resonant transmission of surface plasmon polariton waves through lithographically patterned films of silver nanorod (100 nm in diameter) micro-hole arrays. The best enhancement in surface plasmon resonant transmission is obtained when the nanorods are perfectly aligned with the electric field direction of the linearly polarized terahertz wave. This unique polarization-dependent propagation of surface plasmons in structures fabricated from nanorod films offers promising device applications. We conclude that the anisotropy of nanoscale metallic rod arrays imparts a material anisotropy relevant at the microscale that may be utilized for the fabrication of plasmonic and metamaterial based devices for operation at terahertz frequencies.