Simulation of a Thermally Efficient HAMR Ridge Waveguide NFT on an AIN Heat Sink

Heat-assisted magnetic recording (HAMR) promises to increase the areal data density in hard disk drives beyond 1 Tb/in 2 by raising the temperature of the media to its Curie temperature for writing. The metallic optical near-field transducer (NFT) is a key component of the HAMR system. It confines optical energy to a small region below the diffraction limit on the recording media. The challenge with HAMR is that the NFT can reach extreme temperatures due to self-heating. Therefore, thermal reliability of the NFT is of great importance. To help the NFT dissipate heat, AlN is a potential heat sink material with reported thermal conductivity higher than 100 W/m-K [1] . In this work, we proposed a thermally efficient HAMR light delivery system using a ridge waveguide on an AlN heat sink. The relatively large metallic waveguide structure can dissipate heat effectively even in the presence of finite interface thermal conductance while still producing a small thermal spot in the medium. The thermal efficiencies ( TE ), defined as the ratio of peak temperature rise in the medium versus in the NFT can be as high as 2.93 in our design.