Ultrafast acousto-optic modulation at the near-infrared spectral range by interlayer vibrations

• Published in: Nanophotonics (Berlin, Germany) Vol. 13; no. 7; pp. 1059 - 1068
• Main Authors: Park, Tae Gwan, Kim, Chaeyoon, Oh, Eon-Taek, Na, Hong Ryeol, Chun, Seung-Hyun, Lee, Sunghun, Rotermund, Fabian
• Format: Journal Article
• Language: English
• Published: Berlin De Gruyter 27.03.2024; Walter de Gruyter GmbH
• Subjects: Acoustics; acousto-optic modulation; Acousto-optics; Bismuth; coherent acoustic phonons; Energy; Infrared spectra; Interlayers; Light modulation; Line shape; Measurement techniques; Near infrared radiation; Optical communication; Optical properties; Optical transition; Optics; Optoelectronic devices; photoelastic effect; Physics; Spectrum analysis; Thin films; two-dimensional materials; ultrafast optics
• ISSN: 2192-8614; 2192-8606; 2192-8614
• DOI: 10.1515/nanoph-2023-0769

The acousto-optic modulation over a broad near-infrared (NIR) spectrum with high speed, excellent integrability, and relatively simple scheme is crucial for the application of next-generation opto-electronic and photonic devices. This study aims to experimentally demonstrate ultrafast acousto-optic phenomena in the broad NIR spectral range of 0.77–1.1 eV (1130–1610 nm). Hundreds of GHz of light modulation are revealed in an all-optical configuration by combining ultrafast optical spectroscopy and light–sound conversion in 10–20 nm-thick bismuth selenide (Bi Se ) van der Waals thin films. The modified optical transition energy and the line shape in the NIR band indicate phonon–photon interactions, resulting in a modulation of optical characteristics by the photoexcited interlayer vibrations in Bi Se . This all-optical, ultrafast acousto-optic modulation approach may open avenues for next-generation nanophotonic applications, including optical communications and processing, due to the synergistic combination of large-area capability, high photo-responsivity, and frequency tunability in the NIR spectral range.