Abstract

We describe the application of partial-response (PR) signaling in rewritable phase-change optical data storage. No electronic filter is necessary to shape the readout signal to a certain PR target. A PR-like waveform at the output of the read channel is directly achieved by optical recording. A genetic algorithm is used to optimize the parameters for writing and therefore to minimize the difference between the actual readout signal and the ideal PR waveform. With a laser wavelength of 0.66 µm and an objective lens with a numerical aperture of 0.6, four linear densities were examined: 0.4, 0.3, 0.25, and 0.2 µm/bit (without modulation). Results showed that the linear density of 0.25 µm/bit can be realized on a rewritable digital-versatile disk.

© 2002 Optical Society of America

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References

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  1. J. Feinleib, J. de Nuerville, S. C. Moss, S. R. Ovshinsky, “Rapid reversible light-induced crystallization of amorphous semiconductors,” Appl. Phys. Lett. 18, 254–257 (1971).
    [CrossRef]
  2. T. Ohta, K. Inoue, M. Uchida, K. Yoshioka, T. Akiyama, S. Furukawa, K. Nagata, S. Nakamura, “Phase-change disk media having rapid cooling structure,” Jpn. J. Appl. Phys. 28, Suppl. 28-3, 123–128 (1989).
  3. M. Libera, M. Chen, “Multilayered thin-film materials for phase-change erasable storage,” MRS Bull., April, 40–45 (1990).
  4. T. Ohta, N. Akahira, S. Ohara, I. Satoh, “High density phase-change optical recording,” Optoelectron. Devices Technol. 10, 361–380 (1995).
  5. C. Peng, L. Cheng, M. Mansuripur, “Experimental and theoretical investigation of laser-inducedcrystallization and amorphization in phase-change optical recording media,” J. Appl. Phys. 82, 4183–4191 (1997).
    [CrossRef]
  6. K. A. S. Immink, “Coding methods for high-density optical recording,” Philips J. Res. 41, 410–430 (1986).
  7. P. H. Siegel, J. K. Wolf, “Modulation and coding for information storage,” IEEE Trans. Commun. 39, 68–86 (1991).
  8. M. Yamaguchi, T. Togashi, S. Jinno, H. Kudo, E. Muramatsu, S. Taniguchi, A. Inoue, “4.7 GB phase-change optical disc with in-groove recording,” Jpn. J. Appl. 38, 1806–1810 (1999).
    [CrossRef]
  9. P. Kabal, S. Pasupathy, “Partial-response signaling,” IEEE Trans. Commun. COM-23, 921–934 (1975).
    [CrossRef]
  10. H. Kobayashi, “Correlative level coding and maximum likelihood decoding,” IEEE Trans. Inf. Theory IT-17, 586–594 (1971).
    [CrossRef]
  11. H. Kobayashi, D. T. Tang, “Application of partial-response channel coding to magnetic recording system,” IBM J. Res. Dev. 15, 65–74 (1971).
    [CrossRef]
  12. R. D. Cideciyan, F. Dolivo, R. Hermann, W. Hirt, W. Schott, “A PRML system for digital magnetic recording,” IEEE J. Sel. Areas Commun. 10, 38–56 (1992).
    [CrossRef]
  13. R. T. Lynch, “Channels and codes for magnetooptical recording,” IEEE J. Sel. Areas Commun. 10, 57–72 (1992).
    [CrossRef]
  14. T. Narahara, K. Aratani, A. Fukumoto, S. Masuhara, “Partial-response maximum-likelihoodmethod for magneto-optical recording,” Jpn. J. Appl. Phys. Part I 36, 549–566 (1997).
    [CrossRef]
  15. Chubing Peng, M. Mansuripur, “Evaluation of partial-response maximum-likelihood detection for phase-change optical data storage,” Appl. Opt. 38, 4394–4405 (1999).
    [CrossRef]
  16. J. H. Holland, Adaptation in Natural and Artificial Systems (University of Michigan Press, Ann Arbor, Mich., 1975).
  17. D. E. Goldberg, Genetic Algorithms in Search, Optimization and Machine Learning (Addison-Wesley, Reading, Mass., 1989).

1999 (2)

M. Yamaguchi, T. Togashi, S. Jinno, H. Kudo, E. Muramatsu, S. Taniguchi, A. Inoue, “4.7 GB phase-change optical disc with in-groove recording,” Jpn. J. Appl. 38, 1806–1810 (1999).
[CrossRef]

Chubing Peng, M. Mansuripur, “Evaluation of partial-response maximum-likelihood detection for phase-change optical data storage,” Appl. Opt. 38, 4394–4405 (1999).
[CrossRef]

1997 (2)

T. Narahara, K. Aratani, A. Fukumoto, S. Masuhara, “Partial-response maximum-likelihoodmethod for magneto-optical recording,” Jpn. J. Appl. Phys. Part I 36, 549–566 (1997).
[CrossRef]

C. Peng, L. Cheng, M. Mansuripur, “Experimental and theoretical investigation of laser-inducedcrystallization and amorphization in phase-change optical recording media,” J. Appl. Phys. 82, 4183–4191 (1997).
[CrossRef]

1995 (1)

T. Ohta, N. Akahira, S. Ohara, I. Satoh, “High density phase-change optical recording,” Optoelectron. Devices Technol. 10, 361–380 (1995).

1992 (2)

R. D. Cideciyan, F. Dolivo, R. Hermann, W. Hirt, W. Schott, “A PRML system for digital magnetic recording,” IEEE J. Sel. Areas Commun. 10, 38–56 (1992).
[CrossRef]

R. T. Lynch, “Channels and codes for magnetooptical recording,” IEEE J. Sel. Areas Commun. 10, 57–72 (1992).
[CrossRef]

1991 (1)

P. H. Siegel, J. K. Wolf, “Modulation and coding for information storage,” IEEE Trans. Commun. 39, 68–86 (1991).

1990 (1)

M. Libera, M. Chen, “Multilayered thin-film materials for phase-change erasable storage,” MRS Bull., April, 40–45 (1990).

1989 (1)

T. Ohta, K. Inoue, M. Uchida, K. Yoshioka, T. Akiyama, S. Furukawa, K. Nagata, S. Nakamura, “Phase-change disk media having rapid cooling structure,” Jpn. J. Appl. Phys. 28, Suppl. 28-3, 123–128 (1989).

1986 (1)

K. A. S. Immink, “Coding methods for high-density optical recording,” Philips J. Res. 41, 410–430 (1986).

1975 (1)

P. Kabal, S. Pasupathy, “Partial-response signaling,” IEEE Trans. Commun. COM-23, 921–934 (1975).
[CrossRef]

1971 (3)

H. Kobayashi, “Correlative level coding and maximum likelihood decoding,” IEEE Trans. Inf. Theory IT-17, 586–594 (1971).
[CrossRef]

H. Kobayashi, D. T. Tang, “Application of partial-response channel coding to magnetic recording system,” IBM J. Res. Dev. 15, 65–74 (1971).
[CrossRef]

J. Feinleib, J. de Nuerville, S. C. Moss, S. R. Ovshinsky, “Rapid reversible light-induced crystallization of amorphous semiconductors,” Appl. Phys. Lett. 18, 254–257 (1971).
[CrossRef]

Akahira, N.

T. Ohta, N. Akahira, S. Ohara, I. Satoh, “High density phase-change optical recording,” Optoelectron. Devices Technol. 10, 361–380 (1995).

Akiyama, T.

T. Ohta, K. Inoue, M. Uchida, K. Yoshioka, T. Akiyama, S. Furukawa, K. Nagata, S. Nakamura, “Phase-change disk media having rapid cooling structure,” Jpn. J. Appl. Phys. 28, Suppl. 28-3, 123–128 (1989).

Aratani, K.

T. Narahara, K. Aratani, A. Fukumoto, S. Masuhara, “Partial-response maximum-likelihoodmethod for magneto-optical recording,” Jpn. J. Appl. Phys. Part I 36, 549–566 (1997).
[CrossRef]

Chen, M.

M. Libera, M. Chen, “Multilayered thin-film materials for phase-change erasable storage,” MRS Bull., April, 40–45 (1990).

Cheng, L.

C. Peng, L. Cheng, M. Mansuripur, “Experimental and theoretical investigation of laser-inducedcrystallization and amorphization in phase-change optical recording media,” J. Appl. Phys. 82, 4183–4191 (1997).
[CrossRef]

Cideciyan, R. D.

R. D. Cideciyan, F. Dolivo, R. Hermann, W. Hirt, W. Schott, “A PRML system for digital magnetic recording,” IEEE J. Sel. Areas Commun. 10, 38–56 (1992).
[CrossRef]

de Nuerville, J.

J. Feinleib, J. de Nuerville, S. C. Moss, S. R. Ovshinsky, “Rapid reversible light-induced crystallization of amorphous semiconductors,” Appl. Phys. Lett. 18, 254–257 (1971).
[CrossRef]

Dolivo, F.

R. D. Cideciyan, F. Dolivo, R. Hermann, W. Hirt, W. Schott, “A PRML system for digital magnetic recording,” IEEE J. Sel. Areas Commun. 10, 38–56 (1992).
[CrossRef]

Feinleib, J.

J. Feinleib, J. de Nuerville, S. C. Moss, S. R. Ovshinsky, “Rapid reversible light-induced crystallization of amorphous semiconductors,” Appl. Phys. Lett. 18, 254–257 (1971).
[CrossRef]

Fukumoto, A.

T. Narahara, K. Aratani, A. Fukumoto, S. Masuhara, “Partial-response maximum-likelihoodmethod for magneto-optical recording,” Jpn. J. Appl. Phys. Part I 36, 549–566 (1997).
[CrossRef]

Furukawa, S.

T. Ohta, K. Inoue, M. Uchida, K. Yoshioka, T. Akiyama, S. Furukawa, K. Nagata, S. Nakamura, “Phase-change disk media having rapid cooling structure,” Jpn. J. Appl. Phys. 28, Suppl. 28-3, 123–128 (1989).

Goldberg, D. E.

D. E. Goldberg, Genetic Algorithms in Search, Optimization and Machine Learning (Addison-Wesley, Reading, Mass., 1989).

Hermann, R.

R. D. Cideciyan, F. Dolivo, R. Hermann, W. Hirt, W. Schott, “A PRML system for digital magnetic recording,” IEEE J. Sel. Areas Commun. 10, 38–56 (1992).
[CrossRef]

Hirt, W.

R. D. Cideciyan, F. Dolivo, R. Hermann, W. Hirt, W. Schott, “A PRML system for digital magnetic recording,” IEEE J. Sel. Areas Commun. 10, 38–56 (1992).
[CrossRef]

Holland, J. H.

J. H. Holland, Adaptation in Natural and Artificial Systems (University of Michigan Press, Ann Arbor, Mich., 1975).

Immink, K. A. S.

K. A. S. Immink, “Coding methods for high-density optical recording,” Philips J. Res. 41, 410–430 (1986).

Inoue, A.

M. Yamaguchi, T. Togashi, S. Jinno, H. Kudo, E. Muramatsu, S. Taniguchi, A. Inoue, “4.7 GB phase-change optical disc with in-groove recording,” Jpn. J. Appl. 38, 1806–1810 (1999).
[CrossRef]

Inoue, K.

T. Ohta, K. Inoue, M. Uchida, K. Yoshioka, T. Akiyama, S. Furukawa, K. Nagata, S. Nakamura, “Phase-change disk media having rapid cooling structure,” Jpn. J. Appl. Phys. 28, Suppl. 28-3, 123–128 (1989).

Jinno, S.

M. Yamaguchi, T. Togashi, S. Jinno, H. Kudo, E. Muramatsu, S. Taniguchi, A. Inoue, “4.7 GB phase-change optical disc with in-groove recording,” Jpn. J. Appl. 38, 1806–1810 (1999).
[CrossRef]

Kabal, P.

P. Kabal, S. Pasupathy, “Partial-response signaling,” IEEE Trans. Commun. COM-23, 921–934 (1975).
[CrossRef]

Kobayashi, H.

H. Kobayashi, “Correlative level coding and maximum likelihood decoding,” IEEE Trans. Inf. Theory IT-17, 586–594 (1971).
[CrossRef]

H. Kobayashi, D. T. Tang, “Application of partial-response channel coding to magnetic recording system,” IBM J. Res. Dev. 15, 65–74 (1971).
[CrossRef]

Kudo, H.

M. Yamaguchi, T. Togashi, S. Jinno, H. Kudo, E. Muramatsu, S. Taniguchi, A. Inoue, “4.7 GB phase-change optical disc with in-groove recording,” Jpn. J. Appl. 38, 1806–1810 (1999).
[CrossRef]

Libera, M.

M. Libera, M. Chen, “Multilayered thin-film materials for phase-change erasable storage,” MRS Bull., April, 40–45 (1990).

Lynch, R. T.

R. T. Lynch, “Channels and codes for magnetooptical recording,” IEEE J. Sel. Areas Commun. 10, 57–72 (1992).
[CrossRef]

Mansuripur, M.

Chubing Peng, M. Mansuripur, “Evaluation of partial-response maximum-likelihood detection for phase-change optical data storage,” Appl. Opt. 38, 4394–4405 (1999).
[CrossRef]

C. Peng, L. Cheng, M. Mansuripur, “Experimental and theoretical investigation of laser-inducedcrystallization and amorphization in phase-change optical recording media,” J. Appl. Phys. 82, 4183–4191 (1997).
[CrossRef]

Masuhara, S.

T. Narahara, K. Aratani, A. Fukumoto, S. Masuhara, “Partial-response maximum-likelihoodmethod for magneto-optical recording,” Jpn. J. Appl. Phys. Part I 36, 549–566 (1997).
[CrossRef]

Moss, S. C.

J. Feinleib, J. de Nuerville, S. C. Moss, S. R. Ovshinsky, “Rapid reversible light-induced crystallization of amorphous semiconductors,” Appl. Phys. Lett. 18, 254–257 (1971).
[CrossRef]

Muramatsu, E.

M. Yamaguchi, T. Togashi, S. Jinno, H. Kudo, E. Muramatsu, S. Taniguchi, A. Inoue, “4.7 GB phase-change optical disc with in-groove recording,” Jpn. J. Appl. 38, 1806–1810 (1999).
[CrossRef]

Nagata, K.

T. Ohta, K. Inoue, M. Uchida, K. Yoshioka, T. Akiyama, S. Furukawa, K. Nagata, S. Nakamura, “Phase-change disk media having rapid cooling structure,” Jpn. J. Appl. Phys. 28, Suppl. 28-3, 123–128 (1989).

Nakamura, S.

T. Ohta, K. Inoue, M. Uchida, K. Yoshioka, T. Akiyama, S. Furukawa, K. Nagata, S. Nakamura, “Phase-change disk media having rapid cooling structure,” Jpn. J. Appl. Phys. 28, Suppl. 28-3, 123–128 (1989).

Narahara, T.

T. Narahara, K. Aratani, A. Fukumoto, S. Masuhara, “Partial-response maximum-likelihoodmethod for magneto-optical recording,” Jpn. J. Appl. Phys. Part I 36, 549–566 (1997).
[CrossRef]

Ohara, S.

T. Ohta, N. Akahira, S. Ohara, I. Satoh, “High density phase-change optical recording,” Optoelectron. Devices Technol. 10, 361–380 (1995).

Ohta, T.

T. Ohta, N. Akahira, S. Ohara, I. Satoh, “High density phase-change optical recording,” Optoelectron. Devices Technol. 10, 361–380 (1995).

T. Ohta, K. Inoue, M. Uchida, K. Yoshioka, T. Akiyama, S. Furukawa, K. Nagata, S. Nakamura, “Phase-change disk media having rapid cooling structure,” Jpn. J. Appl. Phys. 28, Suppl. 28-3, 123–128 (1989).

Ovshinsky, S. R.

J. Feinleib, J. de Nuerville, S. C. Moss, S. R. Ovshinsky, “Rapid reversible light-induced crystallization of amorphous semiconductors,” Appl. Phys. Lett. 18, 254–257 (1971).
[CrossRef]

Pasupathy, S.

P. Kabal, S. Pasupathy, “Partial-response signaling,” IEEE Trans. Commun. COM-23, 921–934 (1975).
[CrossRef]

Peng, C.

C. Peng, L. Cheng, M. Mansuripur, “Experimental and theoretical investigation of laser-inducedcrystallization and amorphization in phase-change optical recording media,” J. Appl. Phys. 82, 4183–4191 (1997).
[CrossRef]

Peng, Chubing

Satoh, I.

T. Ohta, N. Akahira, S. Ohara, I. Satoh, “High density phase-change optical recording,” Optoelectron. Devices Technol. 10, 361–380 (1995).

Schott, W.

R. D. Cideciyan, F. Dolivo, R. Hermann, W. Hirt, W. Schott, “A PRML system for digital magnetic recording,” IEEE J. Sel. Areas Commun. 10, 38–56 (1992).
[CrossRef]

Siegel, P. H.

P. H. Siegel, J. K. Wolf, “Modulation and coding for information storage,” IEEE Trans. Commun. 39, 68–86 (1991).

Tang, D. T.

H. Kobayashi, D. T. Tang, “Application of partial-response channel coding to magnetic recording system,” IBM J. Res. Dev. 15, 65–74 (1971).
[CrossRef]

Taniguchi, S.

M. Yamaguchi, T. Togashi, S. Jinno, H. Kudo, E. Muramatsu, S. Taniguchi, A. Inoue, “4.7 GB phase-change optical disc with in-groove recording,” Jpn. J. Appl. 38, 1806–1810 (1999).
[CrossRef]

Togashi, T.

M. Yamaguchi, T. Togashi, S. Jinno, H. Kudo, E. Muramatsu, S. Taniguchi, A. Inoue, “4.7 GB phase-change optical disc with in-groove recording,” Jpn. J. Appl. 38, 1806–1810 (1999).
[CrossRef]

Uchida, M.

T. Ohta, K. Inoue, M. Uchida, K. Yoshioka, T. Akiyama, S. Furukawa, K. Nagata, S. Nakamura, “Phase-change disk media having rapid cooling structure,” Jpn. J. Appl. Phys. 28, Suppl. 28-3, 123–128 (1989).

Wolf, J. K.

P. H. Siegel, J. K. Wolf, “Modulation and coding for information storage,” IEEE Trans. Commun. 39, 68–86 (1991).

Yamaguchi, M.

M. Yamaguchi, T. Togashi, S. Jinno, H. Kudo, E. Muramatsu, S. Taniguchi, A. Inoue, “4.7 GB phase-change optical disc with in-groove recording,” Jpn. J. Appl. 38, 1806–1810 (1999).
[CrossRef]

Yoshioka, K.

T. Ohta, K. Inoue, M. Uchida, K. Yoshioka, T. Akiyama, S. Furukawa, K. Nagata, S. Nakamura, “Phase-change disk media having rapid cooling structure,” Jpn. J. Appl. Phys. 28, Suppl. 28-3, 123–128 (1989).

Appl. Opt. (1)

Appl. Phys. Lett. (1)

J. Feinleib, J. de Nuerville, S. C. Moss, S. R. Ovshinsky, “Rapid reversible light-induced crystallization of amorphous semiconductors,” Appl. Phys. Lett. 18, 254–257 (1971).
[CrossRef]

IBM J. Res. Dev. (1)

H. Kobayashi, D. T. Tang, “Application of partial-response channel coding to magnetic recording system,” IBM J. Res. Dev. 15, 65–74 (1971).
[CrossRef]

IEEE J. Sel. Areas Commun. (2)

R. D. Cideciyan, F. Dolivo, R. Hermann, W. Hirt, W. Schott, “A PRML system for digital magnetic recording,” IEEE J. Sel. Areas Commun. 10, 38–56 (1992).
[CrossRef]

R. T. Lynch, “Channels and codes for magnetooptical recording,” IEEE J. Sel. Areas Commun. 10, 57–72 (1992).
[CrossRef]

IEEE Trans. Commun. (2)

P. Kabal, S. Pasupathy, “Partial-response signaling,” IEEE Trans. Commun. COM-23, 921–934 (1975).
[CrossRef]

P. H. Siegel, J. K. Wolf, “Modulation and coding for information storage,” IEEE Trans. Commun. 39, 68–86 (1991).

IEEE Trans. Inf. Theory (1)

H. Kobayashi, “Correlative level coding and maximum likelihood decoding,” IEEE Trans. Inf. Theory IT-17, 586–594 (1971).
[CrossRef]

J. Appl. Phys. (1)

C. Peng, L. Cheng, M. Mansuripur, “Experimental and theoretical investigation of laser-inducedcrystallization and amorphization in phase-change optical recording media,” J. Appl. Phys. 82, 4183–4191 (1997).
[CrossRef]

Jpn. J. Appl. (1)

M. Yamaguchi, T. Togashi, S. Jinno, H. Kudo, E. Muramatsu, S. Taniguchi, A. Inoue, “4.7 GB phase-change optical disc with in-groove recording,” Jpn. J. Appl. 38, 1806–1810 (1999).
[CrossRef]

Jpn. J. Appl. Phys. (1)

T. Ohta, K. Inoue, M. Uchida, K. Yoshioka, T. Akiyama, S. Furukawa, K. Nagata, S. Nakamura, “Phase-change disk media having rapid cooling structure,” Jpn. J. Appl. Phys. 28, Suppl. 28-3, 123–128 (1989).

Jpn. J. Appl. Phys. Part I (1)

T. Narahara, K. Aratani, A. Fukumoto, S. Masuhara, “Partial-response maximum-likelihoodmethod for magneto-optical recording,” Jpn. J. Appl. Phys. Part I 36, 549–566 (1997).
[CrossRef]

MRS Bull. (1)

M. Libera, M. Chen, “Multilayered thin-film materials for phase-change erasable storage,” MRS Bull., April, 40–45 (1990).

Optoelectron. Devices Technol. (1)

T. Ohta, N. Akahira, S. Ohara, I. Satoh, “High density phase-change optical recording,” Optoelectron. Devices Technol. 10, 361–380 (1995).

Philips J. Res. (1)

K. A. S. Immink, “Coding methods for high-density optical recording,” Philips J. Res. 41, 410–430 (1986).

Other (2)

J. H. Holland, Adaptation in Natural and Artificial Systems (University of Michigan Press, Ann Arbor, Mich., 1975).

D. E. Goldberg, Genetic Algorithms in Search, Optimization and Machine Learning (Addison-Wesley, Reading, Mass., 1989).

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Figures (12)

Fig. 1
Fig. 1

Schematic diagram showing the definition of pulse width and position in a zone.

Fig. 2
Fig. 2

Diagram of the dynamic tester used in our experiments. PBS: polarizing beam splitter; QWP: quarter-wave plate; HWP: half-wave plate.

Fig. 3
Fig. 3

Two normalized signal waveforms representing a 20-bits block at a linear density of 0.4 µm/bit. The solid line denotes the experimentally obtained read waveform, optimized using the genetic algorithm, while the dashed line stands for the waveform constructed from the (1+D) partial-response target.

Fig. 4
Fig. 4

Evolution of the minimum objective function χ as a function of generation. Note that convergence is achieved after approximately 60 generations.

Fig. 5
Fig. 5

Two normalized signal waveforms representing a 20-bits block at a linear density of 0.3 µm/bit. The solid line denotes the experimentally obtained read waveform, optimized using the genetic algorithm, while the dashed line stands for the waveform constructed from the (1+D) partial-response target. T w = 90 ns. In optimization, N z = 3, pulse width = 0, 7.5, 15, 22.5, or 30 ns, write power of each pulse = 3, 18, or 21 mW, and population size = 76.

Fig. 6
Fig. 6

Impulse response (a) and its Fourier transform (b) for five partial-response targets. A: (1+D); b: (1+D)2; c: (1+D)(1+D+D2); d: (1+D)2(1+D+D2); e: (1+D)4. The time (t) scale of the horizontal axis in (a) is normalized by the time window T w while the frequency (f) scale in (b) is normalized by 1/T w .

Fig. 7
Fig. 7

Experimentally optimized read waveforms (solid lines) and ideally constructed waveforms from (1+D)2 PR (dashed lines) for two 20-bits data sequences. The linear density is 0.3 µm/bit. T w = 90 ns. In optimization, N z = 3, pulse width = 0, 7.5, 15, 22.5, or 30 ns, write power of each pulse = 3, 18, or 21 mW, and population size = 76.

Fig. 8
Fig. 8

Same as Fig. 7, but the partial-response target is (1+D)(1+D+D2).

Fig. 9
Fig. 9

Evolution of the minimum objective function χ as a function of generation. As generation < 100, the write power of each pulse is fixed at 18 mW; after 100 generations, the write power can be 3 mW, 18 mW, or 21 mW.

Fig. 10
Fig. 10

Experimentally optimized read waveforms (solid lines) and ideally constructed waveforms from (1+D)(1+D+D2) PR (dashed lines) for two 23-bits data sequences. The linear density is 0.25 µm/bit. T w = 72 ns. In optimization, N z = 2, pulse width = 0, 7.2, 14.4, 21.6, 28.8, or 36 ns, write power of each pulse = 4, 17, or 21 mW, population size = 76.

Fig. 11
Fig. 11

Experimentally optimized read waveforms (solid lines) and ideally constructed waveforms from (1+D)2(1+D+D2) PR (dashed lines) for three data sequences. The linear density is 0.20 µm/bit. T w = 64 ns. In optimization, N z = 2, pulse width = 0, 8, 16, 24, or 32 ns, write power of each pulse = 5, 15, or 20 mW, and population size = 80.

Fig. 12
Fig. 12

Same as Fig. 11 but the partial-response target is (1+D)4.

Equations (2)

Equations on this page are rendered with MathJax. Learn more.

χ=1Nbi=1i=NbSitarget-gRc-Ri2.
Pi=χi-χNg+1i=1Ngχi-χNg+1.

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