Optical Design Challenges of Thermally Assisted Magnetic Recording Heads

Abstract

We developed three home-made modeling programs to design thermally assisted magnetic recording heads: optical beam propagation method for waveguides, optical finite difference time domain method for plasmon generators, and thermal/micromagnetic finite difference method for the recording media. These models lead to the following results. To get higher throughput efficiency of the waveguide, the periodic wavy thickness of the inlet can provide better inlet coupling with laser diode light, and the wavy taper shape can improve the propagation efficiency. As for plasmon generators, the model requires waveguide, recording media and main-pole to estimate the correct performance, because the optimized design depends on all of these parts. Our proposed sharp pointed plasmon generator can provide tiny near field spot, and it must have good scalability for narrow track recording. In addition to these optics models, we performed recording process simulation. As a result, depending on the condition of the thermal spot and head field alignment, either thermal or magnetic field can be dominant in creating the final magnetic transition in the media. The signal to noise ratio and the transition curvature are greatly affected by the recording process.

Tip-based plasmonics: squeezing light with metallic nanoprobes

“…(a) A rectangular waveguide that tapers and channels light towards the NFT. Reprinted with permission from Takano et al Copyright (2010), IEEE. (b) SEM of the E‐antenna with a 10 nm notch to help focus the light.…”

“…Figure a shows a device where light is coupled into a rectangular waveguide through the slider and to the tip. In some designs this waveguide can also be tapered to help more efficiently couple light to the waveguide and deliver it to the tip . The NFT in these devices can be a variety of shapes to efficiently nanofocus the light.…”