[18p-B2-1~15] 4.6 Terahertz Photonics

15:45 〜 16:00奨励賞エントリー英語発表

[18p-B2-9] Terahertz micrometer-scale imaging based on spintronic emitters

〇(D)Ruochen Dai¹, Shinya Isosaki¹, Jiaming Zhang¹, Kosaku Kato¹, Verdad C. Agulto¹, Shojiro Nishitani¹, Mikihiko Nishitani¹, Masashi Yoshimura¹, Makoto Nakajima¹ (1.Osaka Univ. ILE)

キーワード：

terahertz time-domain system、terahertz imaging、spintronic terahertz emitter

In recent years, the terahertz (THz, 0.1–10 THz) region has attracted significant research attention, which can be exploited for nondestructive applications such as biomedical, materials inspection, and security. Therefore, high spatial resolution imaging at THz region of interest is a highly desirable capability in imaging applications. Due to the Abbe diffraction limit, the minimum spatial resolution of microscopy at a given wavelength is λ/2. For imaging in the THz band, this limit is on the order of hundreds of microns. To go beyond this limit, we propose in this study a THz imaging method in which the object is set directly on top of a spintronic THz emitter (STE) made of ferromagnetic/non-magnetic heterojunction, which emits a terahertz signal with a peak frequency of 1THz. A femtosecond laser beam to excite an STE can be focused into a spot size with a diameter of a few microns. Therefore, the excited THz radiation is confined in a few microns just above the STE, which enables the micrometer-scale imaging of an object on top of the STE. Our results demonstrate a spatial resolution of 2.5 μm, below λ/100 for 1 THz.