The Study of Near Field Transducer Performance through Light Behavior Over the Recording Medium

The exceeding temperature at Near Field Transducer (NFT) is a mandatory issue in Heat Assist Magnetic Recording (HAMR). It significantly affects both system performance and lifetime. We believe that light reflection off the recording medium could contribute to the temperature rise in the NFT. In this paper, we study light behavior from the NFT output to the media in terms of powers, using 3-D simulation. We found that the light reflection off the recording layer has certain effects on media absorption rate and NFT coupling efficiency. An increase in the NFT temperature is partly induced by the reflected light. When the surface roughness is included, the reflected power to the NFT obviously decreases. The average absorption rate is reduced more than 50%. The maximum absorption rate and smallest coupling efficiency occurs at the roughness Ra = 0.55 nm.