Simulation Study of Pulse Laser Quality Effects on Recording Performances of Heat-Assisted Magnetic Recording by Short-Pulse Laser Heating

In heat-assisted magnetic recording (HAMR), a higher recording density is pursued. Short-pulse laser heating is a good way to improve the thermal distribution in the media and to reach the full potential of recording density for the HAMR technology. In this paper, the effects of short-pulse laser qualities, such as pulse frequency deviation, pulse power deviation, and pulsewidth deviation, on recording performances for the HAMR with 100 ps pulse laser heating have been analyzed by simulation. The results indicated that the frequency jitter has the most significant effect on the recording performance among these three parameters. The decreases of signal-to-noise ratio (SNR) for 6% deviations of pulse frequency, pulse power, and pulsewidth are 5, 2, and 1.5 dB, respectively. A certain degree phase delay of pulse laser related to magnetic field switching time is beneficial to reducing the effect of pulse frequency deviation on SNR. When the phase delay changes from 0° to 180°, an SNR improvement of ~2 dB is obtained. The measurement result of a real laser diode output (pulsewidth of 97 ps and pulse frequency of 2 GHz) by gain-switching technology presents a very low frequency deviation (<;0.5%). It indicates that the gain-switching technology is a suitable approach for a short-pulse laser generation for the HAMR application.