Simulation on near-field light on recording medium generated by semiconductor ring resonator with metal nano-antenna for
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SPECIAL SECTION: REGULAR PAPER International Symposium on Imaging, Sensing, and Optical Memory (ISOM ’19), Niigata, Japan
Simulation on near‑field light on recording medium generated by semiconductor ring resonator with metal nano‑antenna for heat‑assisted magnetic recording Ryuichi Katayama1 · Satoshi Sugiura2 Received: 25 February 2020 / Accepted: 30 July 2020 © The Optical Society of Japan 2020
Abstract Heat-assisted magnetic recording (HAMR) is a promising technology for achieving more than 10 Tbit/inch2 recording density. A near-field transducer (NFT), which forms a small light spot on a recording medium, is necessary in HAMR. However, the heat generated by the NFT would melt the NFT itself. To solve this problem, the authors have proposed a novel device, in which a metal nano-antenna is attached to a semiconductor ring resonator. In this paper, the near-field light generated by this device was analyzed through a numerical simulation based on a 3-dimensional model including the recording medium to optimize the structure of the device. It was found that how to excite a desired eigenmode selectively among some eigenmodes is important to make the device effective. A light spot with a diameter of about 25 nm, which corresponds to the recording density of 1 Tb/inch2, was obtained on the surface of the recording medium. It was also found that the design parameters of the device must be optimized considering the recording medium. Keywords Heat-assisted magnetic recording · Near-field light · Ring resonator · Nano-antenna · Recording medium · Numerical simulation
1 Introduction In the present information explosion era, there is a prediction that the amount of the data produced all over the world will reach 40 ZB in 2025. Therefore, in hard disk drives, which play an important role in online storage systems, the demand for higher recording density is growing daily. The recording density of hard disk drives is increasing by 30%/year and has reached 816 Gbit/inch2 in 2016. However, to further increase the recording density, the “trilemma” among signalto-noise ratio, thermal stability, and recordability needs to be solved [1]. To secure the signal-to-noise ratio for a smaller * Ryuichi Katayama r‑[email protected] 1
Department of Information Electronics, Faculty of Engineering, Fukuoka Institute of Technology, 3‑30‑1, Wajiro‑higashi, Higashi‑ku, Fukuoka 811‑0295, Japan
InnovaStella, Inc., 465 Ohsato‑cho, Kofu, Yamanashi 400‑0053, Japan
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recorded mark, it is necessary to make the magnetic grain size of the recording medium smaller, thereby increasing the thermal fluctuation and making the recorded mark unstable. To record a smaller mark stably, the recording medium must have a higher coercivity, thereby requiring a higher magnetic field intensity for recording, which is difficult to obtain using a conventional magnetic recording head. To overcome this difficulty and to achieve a recording density of more than 10 Tbit/inch2, a novel technology must be introduced. Heat-assisted magnetic recording (HAMR) [2–
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