Alfredo Sam Chu

HAMR Drive Performance and Integration Challenges

The commercialization of heat-assisted magnetic recording (HAMR) presents some significant technical challenges that need to be resolved before the widespread adoption of the technology can begin. In this paper, we present some HAMR data from prototype drives and discuss some of the challenges related to protrusion management, recording performance optimization, and drive power requirements within the drive.

Recording Performance of a Pulsed HAMR Architecture

In most heat-assisted magnetic recording (HAMR) systems, the laser is ON and kept constant during the entire sector. In this architecture, the transitions are defined whenever the magnetic writer changes polarity. In a pulsed HAMR system, the laser pulses once per bit. In this architecture, the transition is defined by the rising edge of the first laser pulse after a magnetic writer current transition. In this paper, we compare the bit error rate (BER) and areal density capability (ADC) of both continuous wave (CW) HAMR and pulsed HAMR. For our testing conditions, we find that there is no penalty for using a pulsed HAMR system over a CW HAMR system in terms of BER and ADC capability.

Radius and Skew Effects in an HAMR Hard Disk Drive

Over the past year, heat-assisted magnetic recording (HAMR) has continued to make significant progress toward production and remains the most promising technology to enable areal density growth beyond 1 Tb/in2. In this paper, we present an experimental study on the effects of disk radius and head skew angle in a HAMR hard disk drive. We demonstrate the dependence of laser power on disk radius and the sensitivities to several additional factors that can potentially change that characteristic. We also contrast adjacent track interference and areal density capability performance in drive to conventional perpendicular recording and their respective sensitivities to radius and skew angle.

Characterization of HAMR using pulsed laser light

Pulsed Heat Assisted Magnetic Recording (HAMR) is being developed to improve HAMR reliability. In conventional HAMR systems the laser is on and at a fixed power during the writing of the entire sector. In a pulsed HAMR implementation, the laser is turned on and off during the bit cell. For example, for a 50% duty cycle, the laser is on for half the bit cell and off for the remainder of the bit cell. Unlike traditional HAMR where the transitions are formed when the magnetic writer switches, in a pulsed implementation the transitions are formed during the pulsing of the laser. In this paper we show spin stand and drive recording performance of pulsed HAMR systems and compare the outcome to conventional recording. In particular, we show the importance and sensitivity of having proper alignment between the phase of the optical and magnetic signals and their effect on bit error rate (BER).