Ultrabroadband electrically controllable terahertz modulation based on GaAs Schottky diode structure

We demonstrate an ultrabroadband electrically controllable terahertz modulator based on a Schottky diode structure formed with periodic metal microslits on an n-doped GaAs substrate. The mechanism of our design is different from that of the traditional Schottky diode-based THz electrical modulator,...

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Autores principales:	Xudong Liu, Hao Chen, Shixiong Liang, Meng Zhang, Zhendong Jiang, Shuting Fan, Yiwen Sun
Formato:	article
Lenguaje:	EN
Publicado:	AIP Publishing LLC 2021
Materias:	Applied optics. Photonics TA1501-1820
Acceso en línea:	https://doaj.org/article/fde505c042bf462fb348f8be20165474
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spelling	oai:doaj.org-article:fde505c042bf462fb348f8be201654742021-12-01T18:51:31ZUltrabroadband electrically controllable terahertz modulation based on GaAs Schottky diode structure2378-096710.1063/5.0064643https://doaj.org/article/fde505c042bf462fb348f8be201654742021-11-01T00:00:00Zhttp://dx.doi.org/10.1063/5.0064643https://doaj.org/toc/2378-0967We demonstrate an ultrabroadband electrically controllable terahertz modulator based on a Schottky diode structure formed with periodic metal microslits on an n-doped GaAs substrate. The mechanism of our design is different from that of the traditional Schottky diode-based THz electrical modulator, which uses free charge carriers in a substrate to control the resonant behavior of metamaterials. In our device, the modulation is based on free-carrier absorption on the THz wave and therefore broadband. The charge carrier concentration between the metal microslits is actively modified by applying a reverse bias voltage to generate a direct modulation of THz waves. The modulation performance is enhanced by the THz non-resonant electric field enhancement effect from the metal microslits. The experimental results indicate that the modulation depth is positively correlated with the electric field enhancement ratio at the depletion region in the gap and the number of microslits in the THz light spot-covered area. An averaged modulation depth of ∼40% in the measurable frequency range from 0.4 to 1.4 THz was achieved by the device with a metal microslits gap width of 2 µm and a period of 20 µm. A maximum modulation depth of ∼75% was achieved by stacking two devices back-to-back with a 3-dB down bandwidth modulation speed of ∼100 kHz. Further improvements of the device can be achieved by optimizing the parameters such as the free-carrier density in the doping layer, the active area size, and the specifications of the metal microslits.Xudong LiuHao ChenShixiong LiangMeng ZhangZhendong JiangShuting FanYiwen SunAIP Publishing LLCarticleApplied optics. PhotonicsTA1501-1820ENAPL Photonics, Vol 6, Iss 11, Pp 111301-111301-6 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Applied optics. Photonics TA1501-1820
spellingShingle	Applied optics. Photonics TA1501-1820 Xudong Liu Hao Chen Shixiong Liang Meng Zhang Zhendong Jiang Shuting Fan Yiwen Sun Ultrabroadband electrically controllable terahertz modulation based on GaAs Schottky diode structure
description	We demonstrate an ultrabroadband electrically controllable terahertz modulator based on a Schottky diode structure formed with periodic metal microslits on an n-doped GaAs substrate. The mechanism of our design is different from that of the traditional Schottky diode-based THz electrical modulator, which uses free charge carriers in a substrate to control the resonant behavior of metamaterials. In our device, the modulation is based on free-carrier absorption on the THz wave and therefore broadband. The charge carrier concentration between the metal microslits is actively modified by applying a reverse bias voltage to generate a direct modulation of THz waves. The modulation performance is enhanced by the THz non-resonant electric field enhancement effect from the metal microslits. The experimental results indicate that the modulation depth is positively correlated with the electric field enhancement ratio at the depletion region in the gap and the number of microslits in the THz light spot-covered area. An averaged modulation depth of ∼40% in the measurable frequency range from 0.4 to 1.4 THz was achieved by the device with a metal microslits gap width of 2 µm and a period of 20 µm. A maximum modulation depth of ∼75% was achieved by stacking two devices back-to-back with a 3-dB down bandwidth modulation speed of ∼100 kHz. Further improvements of the device can be achieved by optimizing the parameters such as the free-carrier density in the doping layer, the active area size, and the specifications of the metal microslits.
format	article
author	Xudong Liu Hao Chen Shixiong Liang Meng Zhang Zhendong Jiang Shuting Fan Yiwen Sun
author_facet	Xudong Liu Hao Chen Shixiong Liang Meng Zhang Zhendong Jiang Shuting Fan Yiwen Sun
author_sort	Xudong Liu
title	Ultrabroadband electrically controllable terahertz modulation based on GaAs Schottky diode structure
title_short	Ultrabroadband electrically controllable terahertz modulation based on GaAs Schottky diode structure
title_full	Ultrabroadband electrically controllable terahertz modulation based on GaAs Schottky diode structure
title_fullStr	Ultrabroadband electrically controllable terahertz modulation based on GaAs Schottky diode structure
title_full_unstemmed	Ultrabroadband electrically controllable terahertz modulation based on GaAs Schottky diode structure
title_sort	ultrabroadband electrically controllable terahertz modulation based on gaas schottky diode structure
publisher	AIP Publishing LLC
publishDate	2021
url	https://doaj.org/article/fde505c042bf462fb348f8be20165474
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Ultrabroadband electrically controllable terahertz modulation based on GaAs Schottky diode structure

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