Abstract

A supersmall optically switched laser (OSL) head is proposed. A laser diode attached to an air bearing slider forms a complex cavity together with a recording medium, and its light output is detected by a photodetector placed at the other end of the laser facet. Data signals and track error signals read from the sampled servo marks are successfully detected. The signal amplitude variation caused by the flying height change is much reduced, and the SNR is increased to 36 dB (40 kHz to 20 MHz for a phase change medium) by decreasing the reflectivity of the laser facet facing the medium to <5%.

© 1989 Optical Society of America

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References

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  1. H. Ukita, Y. Katagiri, Y. Uenishi, “Readout Characteristics of Micro-Optical Head Operated in Bistable Mode,” Jpn. J. Appl. Phys. 26, Suppl. 26-4, 111–116 (1987).
  2. N. Fukushima, I. Sawaki, “Detection of Magneto-Optic Signal Using External Cavity Laser Diode,” in Technical Digest, Topical Meeting on Optical Data Storage (Optical Society of America, Washington, DC, 1989), pp. 55–58.
  3. Y. Uenishi, Y. Isomura, R. Sawada, H. Ukita, T. Toshima, “Beam Converging Laser Diode by Taper Ridged Waveguide,” Electron. Lett. 24, 623–624 (1988).
    [CrossRef]
  4. M. Ettenberg, H. S. Sommers, H. Kressel, H. F. Lockwood, “Control of Facet Damage in GaAs Laser Diodes,” Appl. Phys. Lett. 18, 571–573 (1971).
    [CrossRef]
  5. H. Ukita, K. Mise, Y. Katagiri, “Simple Measurement of the Reflectivity of Antireflection-Coated Laser Diode Facet,” Jpn. J. Appl. Phys. 27, L1128–L1130 (1988).
    [CrossRef]
  6. N. Tamaru, H. Hosaka, S. Hara, N. Funakoshi, K. Kogure, “A Study of a Flexible Optical Disk Drive,” in Technical Digest, Topical Meeting on Optical Data Storage (Optical Society of America, Washington, DC, 1989), pp. 59–62.
  7. S. Fujimori, S. Yagi, H. Yamazaki, N. Funakoshi, “Crystallization Process of Sb-Te Alloy Films for Optical Storage,” J. Appl. Phys. 64, 1000–1004 (1988).
    [CrossRef]
  8. B. I. Finkelstein, W. C. Williams, “Noise Sources in Magnetooptic Recording,” Appl. Opt. 27, 703–709 (1988).
    [CrossRef] [PubMed]

1988 (4)

Y. Uenishi, Y. Isomura, R. Sawada, H. Ukita, T. Toshima, “Beam Converging Laser Diode by Taper Ridged Waveguide,” Electron. Lett. 24, 623–624 (1988).
[CrossRef]

H. Ukita, K. Mise, Y. Katagiri, “Simple Measurement of the Reflectivity of Antireflection-Coated Laser Diode Facet,” Jpn. J. Appl. Phys. 27, L1128–L1130 (1988).
[CrossRef]

S. Fujimori, S. Yagi, H. Yamazaki, N. Funakoshi, “Crystallization Process of Sb-Te Alloy Films for Optical Storage,” J. Appl. Phys. 64, 1000–1004 (1988).
[CrossRef]

B. I. Finkelstein, W. C. Williams, “Noise Sources in Magnetooptic Recording,” Appl. Opt. 27, 703–709 (1988).
[CrossRef] [PubMed]

1987 (1)

H. Ukita, Y. Katagiri, Y. Uenishi, “Readout Characteristics of Micro-Optical Head Operated in Bistable Mode,” Jpn. J. Appl. Phys. 26, Suppl. 26-4, 111–116 (1987).

1971 (1)

M. Ettenberg, H. S. Sommers, H. Kressel, H. F. Lockwood, “Control of Facet Damage in GaAs Laser Diodes,” Appl. Phys. Lett. 18, 571–573 (1971).
[CrossRef]

Ettenberg, M.

M. Ettenberg, H. S. Sommers, H. Kressel, H. F. Lockwood, “Control of Facet Damage in GaAs Laser Diodes,” Appl. Phys. Lett. 18, 571–573 (1971).
[CrossRef]

Finkelstein, B. I.

Fujimori, S.

S. Fujimori, S. Yagi, H. Yamazaki, N. Funakoshi, “Crystallization Process of Sb-Te Alloy Films for Optical Storage,” J. Appl. Phys. 64, 1000–1004 (1988).
[CrossRef]

Fukushima, N.

N. Fukushima, I. Sawaki, “Detection of Magneto-Optic Signal Using External Cavity Laser Diode,” in Technical Digest, Topical Meeting on Optical Data Storage (Optical Society of America, Washington, DC, 1989), pp. 55–58.

Funakoshi, N.

S. Fujimori, S. Yagi, H. Yamazaki, N. Funakoshi, “Crystallization Process of Sb-Te Alloy Films for Optical Storage,” J. Appl. Phys. 64, 1000–1004 (1988).
[CrossRef]

N. Tamaru, H. Hosaka, S. Hara, N. Funakoshi, K. Kogure, “A Study of a Flexible Optical Disk Drive,” in Technical Digest, Topical Meeting on Optical Data Storage (Optical Society of America, Washington, DC, 1989), pp. 59–62.

Hara, S.

N. Tamaru, H. Hosaka, S. Hara, N. Funakoshi, K. Kogure, “A Study of a Flexible Optical Disk Drive,” in Technical Digest, Topical Meeting on Optical Data Storage (Optical Society of America, Washington, DC, 1989), pp. 59–62.

Hosaka, H.

N. Tamaru, H. Hosaka, S. Hara, N. Funakoshi, K. Kogure, “A Study of a Flexible Optical Disk Drive,” in Technical Digest, Topical Meeting on Optical Data Storage (Optical Society of America, Washington, DC, 1989), pp. 59–62.

Isomura, Y.

Y. Uenishi, Y. Isomura, R. Sawada, H. Ukita, T. Toshima, “Beam Converging Laser Diode by Taper Ridged Waveguide,” Electron. Lett. 24, 623–624 (1988).
[CrossRef]

Katagiri, Y.

H. Ukita, K. Mise, Y. Katagiri, “Simple Measurement of the Reflectivity of Antireflection-Coated Laser Diode Facet,” Jpn. J. Appl. Phys. 27, L1128–L1130 (1988).
[CrossRef]

H. Ukita, Y. Katagiri, Y. Uenishi, “Readout Characteristics of Micro-Optical Head Operated in Bistable Mode,” Jpn. J. Appl. Phys. 26, Suppl. 26-4, 111–116 (1987).

Kogure, K.

N. Tamaru, H. Hosaka, S. Hara, N. Funakoshi, K. Kogure, “A Study of a Flexible Optical Disk Drive,” in Technical Digest, Topical Meeting on Optical Data Storage (Optical Society of America, Washington, DC, 1989), pp. 59–62.

Kressel, H.

M. Ettenberg, H. S. Sommers, H. Kressel, H. F. Lockwood, “Control of Facet Damage in GaAs Laser Diodes,” Appl. Phys. Lett. 18, 571–573 (1971).
[CrossRef]

Lockwood, H. F.

M. Ettenberg, H. S. Sommers, H. Kressel, H. F. Lockwood, “Control of Facet Damage in GaAs Laser Diodes,” Appl. Phys. Lett. 18, 571–573 (1971).
[CrossRef]

Mise, K.

H. Ukita, K. Mise, Y. Katagiri, “Simple Measurement of the Reflectivity of Antireflection-Coated Laser Diode Facet,” Jpn. J. Appl. Phys. 27, L1128–L1130 (1988).
[CrossRef]

Sawada, R.

Y. Uenishi, Y. Isomura, R. Sawada, H. Ukita, T. Toshima, “Beam Converging Laser Diode by Taper Ridged Waveguide,” Electron. Lett. 24, 623–624 (1988).
[CrossRef]

Sawaki, I.

N. Fukushima, I. Sawaki, “Detection of Magneto-Optic Signal Using External Cavity Laser Diode,” in Technical Digest, Topical Meeting on Optical Data Storage (Optical Society of America, Washington, DC, 1989), pp. 55–58.

Sommers, H. S.

M. Ettenberg, H. S. Sommers, H. Kressel, H. F. Lockwood, “Control of Facet Damage in GaAs Laser Diodes,” Appl. Phys. Lett. 18, 571–573 (1971).
[CrossRef]

Tamaru, N.

N. Tamaru, H. Hosaka, S. Hara, N. Funakoshi, K. Kogure, “A Study of a Flexible Optical Disk Drive,” in Technical Digest, Topical Meeting on Optical Data Storage (Optical Society of America, Washington, DC, 1989), pp. 59–62.

Toshima, T.

Y. Uenishi, Y. Isomura, R. Sawada, H. Ukita, T. Toshima, “Beam Converging Laser Diode by Taper Ridged Waveguide,” Electron. Lett. 24, 623–624 (1988).
[CrossRef]

Uenishi, Y.

Y. Uenishi, Y. Isomura, R. Sawada, H. Ukita, T. Toshima, “Beam Converging Laser Diode by Taper Ridged Waveguide,” Electron. Lett. 24, 623–624 (1988).
[CrossRef]

H. Ukita, Y. Katagiri, Y. Uenishi, “Readout Characteristics of Micro-Optical Head Operated in Bistable Mode,” Jpn. J. Appl. Phys. 26, Suppl. 26-4, 111–116 (1987).

Ukita, H.

Y. Uenishi, Y. Isomura, R. Sawada, H. Ukita, T. Toshima, “Beam Converging Laser Diode by Taper Ridged Waveguide,” Electron. Lett. 24, 623–624 (1988).
[CrossRef]

H. Ukita, K. Mise, Y. Katagiri, “Simple Measurement of the Reflectivity of Antireflection-Coated Laser Diode Facet,” Jpn. J. Appl. Phys. 27, L1128–L1130 (1988).
[CrossRef]

H. Ukita, Y. Katagiri, Y. Uenishi, “Readout Characteristics of Micro-Optical Head Operated in Bistable Mode,” Jpn. J. Appl. Phys. 26, Suppl. 26-4, 111–116 (1987).

Williams, W. C.

Yagi, S.

S. Fujimori, S. Yagi, H. Yamazaki, N. Funakoshi, “Crystallization Process of Sb-Te Alloy Films for Optical Storage,” J. Appl. Phys. 64, 1000–1004 (1988).
[CrossRef]

Yamazaki, H.

S. Fujimori, S. Yagi, H. Yamazaki, N. Funakoshi, “Crystallization Process of Sb-Te Alloy Films for Optical Storage,” J. Appl. Phys. 64, 1000–1004 (1988).
[CrossRef]

Appl. Opt. (1)

Appl. Phys. Lett. (1)

M. Ettenberg, H. S. Sommers, H. Kressel, H. F. Lockwood, “Control of Facet Damage in GaAs Laser Diodes,” Appl. Phys. Lett. 18, 571–573 (1971).
[CrossRef]

Electron. Lett. (1)

Y. Uenishi, Y. Isomura, R. Sawada, H. Ukita, T. Toshima, “Beam Converging Laser Diode by Taper Ridged Waveguide,” Electron. Lett. 24, 623–624 (1988).
[CrossRef]

J. Appl. Phys. (1)

S. Fujimori, S. Yagi, H. Yamazaki, N. Funakoshi, “Crystallization Process of Sb-Te Alloy Films for Optical Storage,” J. Appl. Phys. 64, 1000–1004 (1988).
[CrossRef]

Jpn. J. Appl. Phys. (2)

H. Ukita, K. Mise, Y. Katagiri, “Simple Measurement of the Reflectivity of Antireflection-Coated Laser Diode Facet,” Jpn. J. Appl. Phys. 27, L1128–L1130 (1988).
[CrossRef]

H. Ukita, Y. Katagiri, Y. Uenishi, “Readout Characteristics of Micro-Optical Head Operated in Bistable Mode,” Jpn. J. Appl. Phys. 26, Suppl. 26-4, 111–116 (1987).

Other (2)

N. Fukushima, I. Sawaki, “Detection of Magneto-Optic Signal Using External Cavity Laser Diode,” in Technical Digest, Topical Meeting on Optical Data Storage (Optical Society of America, Washington, DC, 1989), pp. 55–58.

N. Tamaru, H. Hosaka, S. Hara, N. Funakoshi, K. Kogure, “A Study of a Flexible Optical Disk Drive,” in Technical Digest, Topical Meeting on Optical Data Storage (Optical Society of America, Washington, DC, 1989), pp. 59–62.

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Figures (18)

Fig. 1
Fig. 1

(a) Schematic representation of a new type optical disk, (b) OSL head on a slider, and (c) a beam-converging laser diode with a taper ridged waveguide.

Fig. 2
Fig. 2

Experimental setup consisting of an OSL head on a slider and a 130-mm diam rotating optical disk.

Fig. 3
Fig. 3

Configuration of OSL head.

Fig. 4
Fig. 4

Relation between the light output of an OSL head and bias current. The medium reflectivities in the two states are R 3 h = 0.35 and R 3 l = 0.04 . Data signals are detected as light output difference between the two states under proper bias current.

Fig. 5
Fig. 5

Signal amplitude and leading edge response to bias current. The white circles are Spp (measured from base to peak), and the black circles are Tr (measured from 10 to 90% of the leading edge).

Fig. 6
Fig. 6

Threshold current ratio vs power ratio for CSP laser diodes with various facet reflectivities.

Fig. 7
Fig. 7

Calculated power ratio of a complex cavity laser for an external cavity length h = 1 μm with external medium reflectivity R3 as a parameter. The threshold currents of an AR coated and an uncoated laser are Ith and I th 0 , respectively.

Fig. 8
Fig. 8

Sampled servo marks consisting of clock marks and wobbling marks.

Fig. 9
Fig. 9

Examples of sampled servo signal waveforms. Track error signals are detected as the light output difference between the two wobbling signals at sampled times t1 and t2

Fig. 10
Fig. 10

Cross marks (×) formed by the envelope of wobbling signals. The marks are found to be linearly dependent on the light beam deviation from the track center.

Fig. 11
Fig. 11

Relationship between flying heights of two kinds of Whitney type slider (A and B) and disk velocity. The circles indicate experimental measurements, while the solid lines indicate numerical results.

Fig. 12
Fig. 12

Variation of the readout OSL head signal amplitude against slider flying height. The optical disk consists of a SbTe phase-change medium sandwiched between dielectric films.

Fig. 13
Fig. 13

Flying height dependence on complex cavity laser light output with laser facet reflectivity R2 facing the medium as a parameter.

Fig. 14
Fig. 14

Relationship between the decrease in complex cavity laser light output amplitude modulation and the reflectivity of the laser facet facing the medium, where flying height h = 1.25 μm and the medium reflectivity R3 = 0.30.

Fig. 15
Fig. 15

Frequency spectrum example of intensity noise for an OSL head.

Fig. 16
Fig. 16

Effective noise levels for an OSL head.

Fig. 17
Fig. 17

Dependence of effective noise Nrms on flying height.

Fig. 18
Fig. 18

SNR vs flying height for an OSL head whose laser facet reflectivity facing the medium is 0.06. The flying height between an OSL head and recording medium surface varies with disk velocity.

Equations (2)

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S p p = S p p ( I ) / S p p ( 60 mA ) , T r = T r ( I ) V / d ,
SNR = 20 log S p p / 2 2 N rms ,

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