Relationship Between Near Field Optical Transducer Laser Absorption and Its Efficiency

Heat-assisted magnetic recording (HAMR) has shown its promising application for recording density beyond 1 Tb/in² . However, the reliability/lifetime of the near field optical transducer is a big challenge. The temperature rise of the transducer is one of the reasons that lead to its failure. In this paper, the laser absorption of the transducer is investigated compared with the transducer efficiency (high efficiency is one of the main targets in the transducer design). The results show that with a fix medium and fix transducer material, high efficiency is always accompanied by high laser absorption which could be 10-25%. High efficiency and low absorption can be obtained by optimizing the medium properties and using transducer material with low refractive index. With the built HAMR head model, the transducer temperature rise is evaluated. The results show that the transducer temperature increase depends on the absorbed power, its size, and the space between the transducer and magnetic pole. The space affects the transducer temperature rise more seriously in large transducer size. Big size is preferable for the transducer to reduce its temperature increase.