Kyoto University · Physics and Astronomy
Professor Tomoki Hiraoka's research lab specializes in terahertz science and nanophotonics, focusing on the generation, manipulation, and application of terahertz radiation using novel semiconductor devices and nanostructured materials. Key research directions include terahertz frequency combs, ultrafast optical control in 2D materials, and the interaction of structured light—such as vortex beams with orbital angular momentum—with metamaterials and plasmonic systems. The lab develops compact, low-power, and room-temperature-compatible terahertz sources for applications in high-speed communications, molecular spectroscopy, and ultrafast electronics.
Figures are computed from collected data and may differ slightly.
The emergence of the vortex beam with orbital angular momentum (OAM) has provided intriguing possibilities to induce optical transitions beyond the framework of the electric dipole interaction. The uniqueness stems from the OAM transfer from light to material, as demonstrated in electronic transitions in atomic systems. In this study, we report on the OAM transfer to electrons in solid-state systems, which has been elusive to date. Using metamaterials (periodically textured metallic disks), we s
Optical frequency combs in the terahertz frequency range are long-awaited frequency standards for spectroscopy of molecules and high-speed wireless communications. However, a terahertz frequency comb based on a low-cost, energy-efficient, and room-temperature-operating device remains unavailable especially in the frequency range of 0.1 to 3 THz. In this paper, we show that the resonant-tunneling-diode (RTD) oscillator can be passively mode-locked by optical feedback and generate a terahertz freq
Layered two-dimensional (2D) materials offer many promising avenues for advancing modern electronics, thanks to their tunable optical, electronic, and magnetic properties. Applying a strong electric field perpendicular to the layers, typically at the MV/cm level, is a highly effective way to control these properties. However, conventional methods to induce such fields employ electric circuit - based gating techniques, which are restricted to microwave response rates and face challenges in achiev
A resonant tunneling diode oscillator has been successfully injection-locked to a continuous terahertz wave. The locking range is about 50 MHz when the RTD emission power and the injection power are set to 10 μW and 4 μW, respectively. The dependence of the locking range to the injection power is consistent with the Adler's theory.
All the raw data and processed data used in the figures in the main text and Supplementary Information in the article "Passive mode-locking and terahertz frequency comb generation in resonant-tunneling-diode oscillator."
All the raw data and processed data used in the figures in the main text and Supplementary Information in the article "Passive mode-locking and terahertz frequency comb generation in resonant-tunneling-diode oscillator."
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