{"title":"Switchable-coupling terahertz directional coupler operating at 100 GHz.","authors":"Zhen Zhang, Sen Qiu, Jikun Zhang, Xiongbin Liu, Wu Pan, Yandong Xiao, Xin Chen, Chaoyi Huang, Dandan Wen, Renpu Li, Xiaoyu Ma","doi":"10.1364/AO.570552","DOIUrl":null,"url":null,"abstract":"<p><p>In the frequency range of 90-110 GHz, we show a dynamically tunable terahertz directional coupler based on the phase transition properties of vanadium dioxide, allowing for a continuous coupling ration adjustment from -3 to -5<i>d</i><i>B</i>. To validate the concept experimentally, we created two metallic-dielectric hybrid counterparts that mimic the coupling effects of the <i>V</i><i>O</i><sub>2</sub> film in both its metallic (shielded branches) and extremely insulating (fully conductive branches) phase states. For -3 and -5<i>d</i><i>B</i> coupler configurations, respectively, simulation results in the 90-110 GHz range show a coupling degree of -2.1 (0.7 dB imbalance) and -3.8<i>d</i><i>B</i> (1.0 dB imbalance). The mode coupling dynamics in terahertz directional couplers were investigated through the branch-line waveguide theory, revealing the underlying transmission mechanism. The experimental results for the coupler's S-parameters were in relatively good agreement with the theoretical predictions. The switchable directional coupler proposed in this paper has applications in dynamic terahertz power allocation, terahertz imaging, and electromagnetic stealth.</p>","PeriodicalId":101299,"journal":{"name":"Applied optics","volume":"64 26","pages":"7677-7684"},"PeriodicalIF":0.0000,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Applied optics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1364/AO.570552","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
In the frequency range of 90-110 GHz, we show a dynamically tunable terahertz directional coupler based on the phase transition properties of vanadium dioxide, allowing for a continuous coupling ration adjustment from -3 to -5dB. To validate the concept experimentally, we created two metallic-dielectric hybrid counterparts that mimic the coupling effects of the VO2 film in both its metallic (shielded branches) and extremely insulating (fully conductive branches) phase states. For -3 and -5dB coupler configurations, respectively, simulation results in the 90-110 GHz range show a coupling degree of -2.1 (0.7 dB imbalance) and -3.8dB (1.0 dB imbalance). The mode coupling dynamics in terahertz directional couplers were investigated through the branch-line waveguide theory, revealing the underlying transmission mechanism. The experimental results for the coupler's S-parameters were in relatively good agreement with the theoretical predictions. The switchable directional coupler proposed in this paper has applications in dynamic terahertz power allocation, terahertz imaging, and electromagnetic stealth.