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5.4 Future Applications 207
110
V (non mark)
1
Reflectivity (%) 100

90

V 2 (mark)
80
1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
Laser power (mW)
Fig. 5.51. Initialization effect on as-depo medium of the scattered type super-
RENS disk with read power of 1 mW, medium velocity of 2 m s −1 , and mark length
of 3,000 nm

30
CNR (dB) 15 300 nm 400 nm

0
1 2 3 4 5 6 7 8 9
(mW)
Initialization power P i
Fig. 5.52. Relationship between CNR of super-RENS readout (P r = 4 mW)and
initialization laser power P i, with mark length as parameter

process in GeSbTe. The maximum positive of the laser power of 3.5 mW shows
that the AgO is fully decomposed to Agparticles and O 2 , both of which are
x
uniformly dispersed in the mask layer. On the other hand, the nonmark reflec-
tivity V 2 remains constant because thermal interference due to the succcessive
laser pulses does not occur for long(3,000 nm) marks.
Figure 5.52 shows the relationship between the CNR for the super-RENS
readout (P r = 4 mW) and the initialization laser power P i , mark length as
a parameter. We define P i =3.5 mW as the initialization laser power where
the CNR for the short mark (under diffraction limit) reaches maximum. The
maximum CNR corresponds to a reproduced signal maximum at P i =3.5mW
in Fig. 5.51, where fully decomposed Ag particles are dispersed in the mask
layer.
Figure 5.53 shows the effect of initialization on the CNR for the super-
RENS readout, with write power P w as a parameter. The CNR with initial-
ization (b) is higher and less dependent on P w than that without initialization
(a). Moreover, we can detect a mark length of 200 nm (duty ratio 50%) because
with initialization the resolution increases.