• 전자통신동향분석
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• 제34권3호
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• pp.75-85
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• 2019

The bandwidth of wireless communication is expected to grow exponentially due to the expansion of mobile devices and the increase of real-time and realistic multimedia services. Recently, the studies on terahertz band wireless communication have been actively conducted for the next generation communication after 5G wireless communication. The terahertz band, which is the unallocated frequency band, has been applied to the non-contact, non-destructive quality inspection industry such as the terahertz imaging and spectral systems through the development of terahertz generating and detecting components. This article briefly describes recent research trends on terahertz wireless communication technologies and introduces the details of photonics-based terahertz devices and systems that have been focused on the Terahertz Basic Research Section of Electronics and Telecommunication Research Institute.

• Journal of electromagnetic engineering and science
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• 제10권3호
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• pp.158-165
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• 2010

This study reviewed terahertz technologies of time domain spectroscopy, T-ray imaging, and high rate wireless data transfer. The main topics of the terahertz research area were investigation of materials and package modules for terahertz wave generation and detection, and setup of the terahertz system for time domain spectroscopy(TDS), T-ray imaging and sub-THz wireless communication. In addition to Poly-GaAs film as a photoconductive switching antenna material, a table-top scale for the THz-TDS/imaging system and terahertz continuous wave(CW) generation systems for sub-THz data transfer and narrow band T-ray imaging were designed. Dielectric properties of ferroelectric BSTO($Ba_xSr_{1-x}TiO_3$) films and chalcogenide glass systems were characterized with the THz-TDS system at the THz frequency range. Package modules for terahertz wave transmitter/receiver(Tx/Rx) photoconductive antenna were developed.

• Current Optics and Photonics
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• 제4권6호
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• pp.461-465
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• 2020

A dual-mode laser terahertz source consisting of two in-line distributed Bragg reflector (DBR) laser diodes (LD) is proposed. It is less susceptible to residual reflections from facets than an in-line dual-mode distributed feedback (DFB) LD. The characteristics of the proposed terahertz source are theoretically investigated using a split-step time-domain simulation. It is shown that terahertz waves of frequencies from 385 GHz to 1725 GHz can be generated by appropriate thermal tuning of two DBR LDs. The dual-mode DBR LD terahertz source exhibits good spectral quality for residual facet reflectivity below 0.02, but facet reflectivity of the in-line dual-mode DFB LD terahertz source should be below 0.002 to provide similar spectral quality.

• 한국정보기술학회 영문논문지
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• 제9권1호
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• pp.11-24
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• 2019

This paper investigates the performance comparison of a Terahertz (THz) communications for a single-carrier and a multi-carrier single antenna point-to-point communication system. The multi-carrier system and single carrier system consider the orthogonal frequency division multiplexing (OFDM) and the minimum mean square error linear equalizer (MMSE-LE), respectively. We compare the frame-error-rate (FER) and throughput performance of both the systems for a THz communication environment with the carrier frequency of 300GHz and the tapped delay line (TDL) channel models described in 3GPP. It is observed from the simulation results that the OFDM systems outperform the MMSE-LE for various configurations.

• Journal of the Optical Society of Korea
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• 제20권2호
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• pp.263-268
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• 2016

Broadband metal-dielectric-metal terahertz filters composed of complementary rings are designed and demonstrated. Four samples with different parameters were fabricated. Results measured using THz time-domain spectroscopy system show excellent agreement with simulations. Compared with the broadband filters reported before, the complementary ring structure in our design is insensitive to any polarization at normal incidence due to symmetry of the ring. Furthermore, the influence of structure parameters (such as period, radius, slot width, thickness and incidence angles) on the transmission characteristics has been investigated theoretically. The encouraging results afforded by designing of the filters could find applications in broadband sensors, terahertz communication systems, and other emerging terahertz technologies.

• Current Optics and Photonics
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• 제2권6호
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• pp.629-634
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• 2018

A broad dual-band terahertz metamaterial filter with sharp out-of-band rejections is designed and demonstrated. The center frequencies of the first and the second bands occur at 0.35 THz and 0.96 THz with 3 dB relative bandwidth of 31% and 17%, respectively. Results are measured using a THz time-domain spectroscopy system that shows agreement with simulations. Physical mechanisms of the broad dual-band resonance are clarified based on transmissions of different structures and surface current density distributions. Influence of structure parameters on the transmission characteristics are discussed. Symmetry of the structure ensures the filter polarization independence at normal incidence. These results supported by the design of the filter could find applications in broad multi-band sensors, terahertz communication systems, and other emerging terahertz technologies.

• ETRI Journal
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• 제35권3호
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• pp.386-396
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• 2013

A 10-Gbit/s wireless communication system operating at a carrier frequency of 300 GHz is presented. The modulation scheme is amplitude shift keying in incoherent mode with a high intermediate frequency (IF) of 30 GHz and a bandwidth of 20 GHz for transmitting a 10-Gbit/s baseband (BB) data signal. A single sideband transmission is implemented using a waveguide-tapered 270-GHz high-pass filter with a lower sideband rejection of around 60 dB. This paper presents an all-electronic design of a terahertz communication system, including the major modules of the BB and IF band as well as the RF modules. The wireless link shows that, aided by a clock and data recovery circuit, it can receive $2^7$-1 pseudorandom binary sequence data without error at up to 10 Gbit/s for over 1.2 m using collimating lenses, where the transmitted power is 10 ${\mu}W$.

• ETRI Journal
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• 제45권2호
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• pp.193-202
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• 2023

We demonstrate the transmission of uncompressed 4K videos over the photonics-based terahertz (THz) wireless link using a directly modulated distributed feedback laser diode (DFB-LD). For optical heterodyne mixing and data modulation, a DFB-LD was employed and directly modulated with a 5.94-Gb/s non-return-to-zero signal, which is related to a 6G-serial digital interface standard to support ultra-high-definition video resolution. We derived the optimal frequency of the THz carrier by varying the wavelength difference between DFB-LD output and Tunable LD output in the THz signal transmitter to obtain the best transmission performances of the uncompressed 4K video signals. Furthermore, we exploited the negative laser-to-filter detuning for the adiabatic chirp management of the DFB-LD by the intentional discrepancy between the center wavelength of the optical band-pass filter and the output wavelength of the DFB-LD. With the help of the abovementioned methods, we successfully transmitted uncompressed 4K video signals over the 2.3-m wireless transmission distance without black frames induced by time synchronization error.

• 전기전자학회논문지
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• 제27권4호
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• pp.411-417
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• 2023

무인 항공기(UAV) 지원 중계는 분포가 쉽고 통신 채널이 양호하며, 이동성이 뛰어나 기존 지상 중계에 비해 높은 무선 연결성을 가질 수 있다. 본 논문에서는 무선 주파수(RF) 대역을 활용하여 소스로부터 에너지를 수확하고 테라헤르츠(THz) 대역을 활용하여 2차 송신기와 해당 수신기 간에 정보를 전송할 수 있는 UAV 지원 중계 네트워크를 설계한다. 그 후, 릴레이 채널 용량을 최대화하는 UAV의 최적 위치를 결정하기 위한 최적화 문제의 해를 유도하고, 유도된 해를 활용하여 두 가지 UAV 궤적(직선 궤적과 타원 궤적)을 설계하는 알고리즘을 제안한다. 시뮬레이션 결과, 제안된 알고리즘은 UAV 직선 궤도가 수확된 에너지 및 채널 용량 측면에서 더 나은 시스템 성능을 제공할 수 있음을 보여준다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권1호
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• pp.102-122
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• 2017

Nanotechnology has provided a set of tools that the engineers can use to design and manufacture integrated nano devices, which are capable of performing sensing, computing, data storing and actuation. One of the main hurdles for nano devices has been the amount of power that it can generate for transmission of data. In this paper, we proposed cooperative nano communication in the Terahertz (THz) Gap frequency band to increase the range of transmission. Outage probability (OP) performances for the proposed cooperative nano communication networks in the THz band (0.1 - 10THz) have been evaluated for the following scenarios; A) A single decode-and-forward (DF) relay over independent identically distributed (i.i.d.) Rayleigh fading channels, B) DF multi-relay network with best relay selection (BRS) over i.i.d. Rayleigh fading channels, and C) DF multi-relay network with multiple hops with BRS over i.i.d. Rayleigh fading channels. The results show that the transmission distance can be improved significantly by employing DF relays. Also, it is shown that by increasing the number of hops in a relay the OP performance is marginally degraded. The analytical results have been verified by Monte-Carlo simulation.