R&D: Enhancing Bottom-Layer Detection in Dual-Layer 3D Magnetic Recording via Top-Layer-Assisted Signal Rescaling

IEEE Transactions on Magnetics has published an article written by Ke Luo, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science & Technology, China, and Engineering Research Center of Data Storage Systems & Technology, Ministry of Education of China, Key Laboratory of Information Storage System, Huazhong University of Science & Technology, China, Yuqian Zhao, Ziqian Liu, Engineering Research Center of Data Storage Systems & Technology, Ministry of Education of China, Key Laboratory of Information Storage System, Huazhong University of Science & Technology, China, and School of Computer Science & Technology, Huazhong University of Science and Technology, China, Yugen Jian, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science & Technology, China, and Engineering Research Center of Data Storage Systems & Technology, Ministry of Education of China, Key Laboratory of Information Storage System, Huazhong University of Science & Technology, China, Simon Greaves, Research Institute of Electrical Communication (RIEC), Tohoku University, Sendai, Japan, Jincai Chen, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science & Technology, China, and Engineering Research Center of Data Storage Systems & Technology, Ministry of Education of China, Key Laboratory of Information Storage System, Huazhong University of Science & Technology, China, Ping Lu, Engineering Research Center of Data Storage Systems & Technology, Ministry of Education of China, Key Laboratory of Information Storage System, Huazhong University of Science & Technology, China, and School of Computer Science & Technology, Huazhong University of Science and Technology, China.

Abstract: “Three-dimensional magnetic recording (3DMR) technologies, such as three-dimensional heat-assisted magnetic recording (3D HAMR) and three-dimensional bit-patterned magnetic recording (3D BPMR), enhance areal density by stacking multiple recording layers and utilizing heat-assisted writing to encode multi-bit data through vertically combined magnetization states. Current 3DMR systems primarily employ dual-layer media (also referred to as dual-layer magnetic recording), where the readback signals from a single head consist of superimposed responses from both the top and bottom layers, leading to significant 3D interference, including inter-symbol interference (ISI), inter-track interference (ITI), and inter-layer interference (ILI). To improve bottom-layer detection reliability in 3DMR, this paper proposes a scaling-based signal extraction method that refines the bottom-layer signal using detected top-layer data. This approach enables efficient one-dimensional detection while significantly reducing the bottom-layer bit error rate (BER). Compared to the previously proposed dual-layer PRML detection, the method maintains the same top-layer BER while achieving an 80% reduction in the bottom-layer BER at the areal density of 3.3 Tb/in². Moreover, it demonstrates superior bottom-layer detection performance across areal densities ranging from 1 to 4.5 Tb/in² per layer (2–9 Tb/in² for dual-layer systems).“