A DWDD disc of 27-Gbit/in²land groove-recording using a blue laser and side-wall-annealing technique

Abstract

We realized acceptable read/write performances at a track pitch of 320 nm and a bit length of 75 nm, even with an NA of 0.65 and a wavelength of 405 nm, using side-wall-annealing. In addition to this result, we suggested the possibility of a higher linear density; that is, a jitter value of less than 15% was obtained both on land and in groove at a bit length of 60 nm, which corresponds to an areal density of 34 Gbit/in 2 .

Anneal-Less Domain Wall Displacement Detection of 27 Gbit/in2 Land/Groove Recording Using a Deep Groove Substrate and a Blue Laser

“…Figure 1 shows a DWDD film stack. The magnetic films are very similar to those already reported 6) and have been adjusted to achieve high performance for an anneal-less type of DWDD. The material and thickness of the Al-alloy heat sink layer were adjusted to balance competing goals for a low jitter value and a high suppression of ghost signals.…”

“…4) Sumioka et al reported a sidewall-annealed DWDD disk that enabled a land/groove recording of 27 Gbit/in 2 with a wavelength of 405 nm and an NA of 0.65. 6) In this paper, using the same optics, we announce the development of an anneal-less DWDD on a deep land/groove substrate that achieves the same areal recording density as a sidewallannealed type.…”

“…Over the past few years, a considerable number of studies have been carried out on DWDD disks using a red laser diode (LD) [2][3][4] and a blue LD. 5,6) Tanaka et al reported two types of DWDD disks, an anneal-less type and a sidewall-annealed type, which enabled a land/groove recording of 15 Gbit/in 2 using a wavelength of 660 nm and a numerical aperture (NA) of 0.6. 4) Sumioka et al reported a sidewall-annealed DWDD disk that enabled a land/groove recording of 27 Gbit/in 2 with a wavelength of 405 nm and an NA of 0.65.…”