{"title":"太赫兹波在砷化镓波导中光学诱导时间边界的频率下变频","authors":"Keisuke Takano, Satoko Uchiyama, Shintaro Nagase, Yuka Tsuchimoto, Toshihiro Nakanishi, Yosuke Nakata, Joel Pérez-Urquizo, Julien Madéo, Keshav M. Dani, Fumiaki Miyamaru","doi":"10.1515/nanoph-2024-0010","DOIUrl":null,"url":null,"abstract":"In this study, the frequency down-conversion of terahertz waves is analytically and experimentally demonstrated at the temporal boundaries within a GaAs waveguide. The temporal boundary is established by photoexciting the top surface of the waveguide, thereby instantaneously increasing its electrical conductivity. This photoexcited waveguide supports a transverse electromagnetic (TEM) mode with a frequency lower than those of the transverse magnetic (TM) modes present in the original waveguide. At the temporal boundary, the incident TM mode couples with the TEM mode, resulting in frequency down-conversion. Subtracting the propagation loss from the frequency-converted components indicates that the frequency conversion occurs with an efficiency consistent with the analytical predictions. The propagation loss is primarily due to ohmic loss, caused by the finite electrical conductivity of the photoexcited region. Given that the frequency of transverse electric modes is up-converted at the temporal boundary, our findings suggest that the direction of frequency conversion (upward or downward) can be controlled by manipulating the incident polarization. The polarization-dependent frequency conversion in waveguides holds significant potential for applications in devices designed for the interconversion of terahertz signals across various frequency channels. This capability is instrumental in the development of frequency-division-multiplexed terahertz wave communication systems, thereby enabling high data transfer rates.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":null,"pages":null},"PeriodicalIF":7.5000,"publicationDate":"2024-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Frequency down-conversion of terahertz waves at optically induced temporal boundaries in GaAs waveguides\",\"authors\":\"Keisuke Takano, Satoko Uchiyama, Shintaro Nagase, Yuka Tsuchimoto, Toshihiro Nakanishi, Yosuke Nakata, Joel Pérez-Urquizo, Julien Madéo, Keshav M. Dani, Fumiaki Miyamaru\",\"doi\":\"10.1515/nanoph-2024-0010\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"In this study, the frequency down-conversion of terahertz waves is analytically and experimentally demonstrated at the temporal boundaries within a GaAs waveguide. 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Given that the frequency of transverse electric modes is up-converted at the temporal boundary, our findings suggest that the direction of frequency conversion (upward or downward) can be controlled by manipulating the incident polarization. The polarization-dependent frequency conversion in waveguides holds significant potential for applications in devices designed for the interconversion of terahertz signals across various frequency channels. 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引用次数: 0
摘要
本研究通过分析和实验证明了太赫兹波在砷化镓波导内时间边界的频率下变频。时间边界是通过光激发波导的顶面而建立的,从而瞬间提高了波导的导电性。这种光激发波导支持一种横向电磁(TEM)模式,其频率低于原始波导中的横向磁(TM)模式。在时间边界,入射的 TM 模式与 TEM 模式耦合,导致频率下变频。从频率转换成分中减去传播损耗表明,频率转换的效率与分析预测一致。传播损耗主要是由于光激发区域的有限导电性造成的欧姆损耗。鉴于横向电模式的频率在时间边界处向上转换,我们的研究结果表明,频率转换的方向(向上或向下)可以通过操纵入射极化来控制。波导中与偏振相关的频率转换具有巨大的应用潜力,可应用于设计用于在不同频率通道间相互转换太赫兹信号的设备中。这种能力有助于开发频分复用太赫兹波通信系统,从而实现高数据传输速率。
Frequency down-conversion of terahertz waves at optically induced temporal boundaries in GaAs waveguides
In this study, the frequency down-conversion of terahertz waves is analytically and experimentally demonstrated at the temporal boundaries within a GaAs waveguide. The temporal boundary is established by photoexciting the top surface of the waveguide, thereby instantaneously increasing its electrical conductivity. This photoexcited waveguide supports a transverse electromagnetic (TEM) mode with a frequency lower than those of the transverse magnetic (TM) modes present in the original waveguide. At the temporal boundary, the incident TM mode couples with the TEM mode, resulting in frequency down-conversion. Subtracting the propagation loss from the frequency-converted components indicates that the frequency conversion occurs with an efficiency consistent with the analytical predictions. The propagation loss is primarily due to ohmic loss, caused by the finite electrical conductivity of the photoexcited region. Given that the frequency of transverse electric modes is up-converted at the temporal boundary, our findings suggest that the direction of frequency conversion (upward or downward) can be controlled by manipulating the incident polarization. The polarization-dependent frequency conversion in waveguides holds significant potential for applications in devices designed for the interconversion of terahertz signals across various frequency channels. This capability is instrumental in the development of frequency-division-multiplexed terahertz wave communication systems, thereby enabling high data transfer rates.
期刊介绍:
Nanophotonics, published in collaboration with Sciencewise, is a prestigious journal that showcases recent international research results, notable advancements in the field, and innovative applications. It is regarded as one of the leading publications in the realm of nanophotonics and encompasses a range of article types including research articles, selectively invited reviews, letters, and perspectives.
The journal specifically delves into the study of photon interaction with nano-structures, such as carbon nano-tubes, nano metal particles, nano crystals, semiconductor nano dots, photonic crystals, tissue, and DNA. It offers comprehensive coverage of the most up-to-date discoveries, making it an essential resource for physicists, engineers, and material scientists.