Liu, Ming-ChenMing-ChenLiuPhan, Mun-WeiMun-WeiPhanMohanty, SheetikantaSheetikantaMohantyTseng, Po-HsienPo-HsienTsengHsieh, Wei-ChiWei-ChiHsiehChen, Szu-HungSzu-HungChenLai, Yu-ShengYu-ShengLaiHSUEN-LI CHEN2026-04-212026-04-212026https://www.scopus.com/record/display.uri?eid=2-s2.0-105033276705&origin=resultslisthttps://scholars.lib.ntu.edu.tw/handle/123456789/737372Recent advancements in fiber-optic communication have established the conventional wavelength of 1550 nm. However, the next generation of telecommunications promises excellent prospects at 2 µm wavelengths via hollow-core photonic-bandgap fibers (HC-PBGFs). Nevertheless, many semiconductors struggle to operate effectively at their intrinsic bandgap due to wavelength redshift. In this work, the gallium arsenide (GaAs) operating band is successfully extended to the 2 µm optical communication band using the GaAs Trench Metal (GATM) structure, enhancing absorptance and overall performance. Notably, the GATM device exhibits a photovoltage responsivity of 5.48 V W−1 under zero bias operation. This remarkable performance is attributed to the surface plasmonic effect and resonant cavity mode, resulting in approximately 3.8 times current gain and about 3 times voltage gain compared to flat film devices. Furthermore, the GATM devices demonstrate exceptional temperature stability, ranging from −195°C to 195°C, highlighting their potential for applications in harsh environments. These devices showcase stable and improved performance wiin the 2 µm optical communication band, ensuring reliable operation across a broad temperature range. Such characteristics make them well-suited for advanced telecommunications technologies.false2 µm optical windowharsh environmenthot carriersoptical communication bandphotodetectionSchottky junctionsurface plasmon resonancejournal article10.1002/adom.2025037322-s2.0-105033276705