Optical multilayer disk, multiwavelength light source, and optical system using them

• US 20060193231A1
• Filed: 04/24/2006
• Published: 08/31/2006
• Est. Priority Date: 10/25/1999
• Status: Abandoned Application

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Yamada, Noboru, Mizuuchi, Kiminori, Kojima, Rie, Yamamoto, Kazuhisa
• Application Number:
  US11/409,762
• Publication Number:
  US 20060193231A1
• Time in Patent Office: Days
• US Class Current: 369/94
• CPC Class Codes: G02B 2006/12164 Multiplexing; Demultiplexing
• CPC Class Codes: G02B 6/126 using polarisation effects G02B6/1226 takes precedence
• CPC Class Codes: G02B 6/29362 Serial cascade of filters or filtering operations, e.g. for a large number of channels
• CPC Class Codes: G02F 1/3532 Arrangements of plural nonlinear devices for generating multi-colour light beams, e.g. arrangements of SHG, SFG, OPO devices for generating RGB light beams
• CPC Class Codes: G02F 1/3544 Particular phase matching techniques
• CPC Class Codes: G02F 1/3548 Quasi phase matching [QPM], e.g. using a periodic domain inverted structure
• CPC Class Codes: G02F 1/3775 with a periodic structure, e.g. domain inversion, for quasi-phase-matching [QPM] G02F1/383 takes precedence
• CPC Class Codes: G02F 2201/18 parallel
• CPC Class Codes: G02F 2203/58 Multi-wavelength, e.g. operation of the device at a plurality of wavelengths
• CPC Class Codes: G11B 2007/0013 for carriers having multiple discrete layers
• CPC Class Codes: G11B 2007/24312 group 14 elements (e.g. Si, Ge, Sn)
• CPC Class Codes: G11B 2007/24314 group 15 elements (e.g. Sb, Bi)
• CPC Class Codes: G11B 2007/24316 group 16 elements (i.e. chalcogenides, Se, Te)
• CPC Class Codes: G11B 7/00454 involving phase-change effects
• CPC Class Codes: G11B 7/005 Reproducing G11B7/0065 takes precedence
• CPC Class Codes: G11B 7/124 the integrated head arrangements including waveguides
• CPC Class Codes: G11B 7/1275 Two or more lasers having different wavelengths
• CPC Class Codes: G11B 7/1395 Beam splitters or combiners G11B7/1353, G11B7/1356 take precedence ; beam splitting or combining per se G02B27/10
• CPC Class Codes: G11B 7/24038 Multiple laminated recording layers
• CPC Class Codes: G11B 7/243 comprising inorganic materials only, e.g. ablative layers
• CPC Class Codes: G11B 7/259 : based on silver
• CPC Class Codes: G11B 7/26 : Apparatus or processes specially adapted for the manufacture of record carriers

Abstract

When a wavelength of a first laser beam with which a first recording medium including a first recording layer is recorded and reproduced is indicated as λ1 (nm), a wavelength of a second laser beam with which a second recording medium including a second recording layer is recorded and reproduced as λ2 (nm), the relationship between the wavelength λ1 and the wavelength λ2 is set to be expressed by 10≦|λ1−λ2|≦120. The first recording layer has a light absorptance ratio of at least 1.0 with respect to the wavelength λ1. The light transmittance of the first recording medium with respect to the wavelength λ2 is set to be at least 30 in both the cases where the recording layer is in a crystal state and in an amorphous state. In order to record and reproduce the optical multilayer disk with the above-mentioned characteristics, a multiwavelength light source with the following configuration is used. Wavelengths of fundamental waves with different wavelengths from injection parts formed at one end of a plurality of optical waveguides, which satisfy phase matching conditions different from one another and are formed in the vicinity of the surface of a substrate, are converted simultaneously, and the first and second laser beams are emitted from emission parts formed at substantially the same position at the other end of the optical waveguides. This enables an optimum optical system for high density recording and reproduction to be obtained.

Claims

1-11. -11. (canceled)

12. A method of recording and reproducing with respect to an optical information recording medium including at least two recording layers formed of a phase change material on a substrate from one side using laser beams,

wherein the recording layers include a first recording layer and a second recording layer from the side on which the laser beams are incident, the first recording layer is included in a first recording medium and the second recording layer is included in a second recording medium,

when a wavelength of a first laser beam with which recording and reproduction are performed with respect to the first recording medium is indicated as λ

1 (nm), and a wavelength of a second laser beam with which the second recording medium is recorded and reproduced as λ

2 (nm), the relationship between the wavelength λ

1 and the wavelength λ

2 is expressed by 10≦

|80 1−

λ

2|≦

120.

13. The method of recording and reproducing with respect to an optical information recording medium according to claim 12, wherein the relationship between the wavelength λ

1 and the wavelength λ

2 is expressed by 10≦

|λ

1−

λ

2|≦

50.

14. The method of recording and reproducing with respect to an optical information recording medium according to claim 12, wherein with respect to an optical information recording medium in which the second recording medium, the first recording medium, and a protective layer are formed on the substrate sequentially and the protective layer has a thickness d1 (μ

m) in a range of 30≦

d1≦

200, recording and reproduction are performed with the first and second laser beams from a side of the protective layer.

15. The method of recording and reproducing with respect to an optical information recording medium according to claim 12, wherein recording and reproduction are performed with respect to an optical information recording medium in which the first recording medium formed on a first substrate and the second recording medium formed on a second substrate are bonded to each other.

16. The method of recording and reproducing with respect to an optical information recording medium according to claim 12, wherein recording and reproduction are performed with a first laser beam and a second laser beam emitted from a multiwavelength light source in which a part of an optical waveguide of a second harmonic generation element and an optical waveguide of a semiconductor laser are optically coupled.

17. The method of recording and reproducing with respect to an optical information recording medium according to claim 12, wherein the wavelength λ

1 (nm) of the first laser beam is in a range of 390≦

λ

1≦

520.

18. An optical waveguide device, comprising:

a substrate;

a plurality of optical waveguides formed in the vicinity of a surface of the substrate;

injection parts formed at one end of the optical waveguides; and

emission parts formed on the other end of the optical waveguides,

wherein the plurality of optical waveguides satisfy phase matching conditions different from one another, and

the emission parts of the plurality of optical waveguides are provided at substantially the same position.

19. The optical waveguide device according to claim 18, wherein the optical waveguides have periodical polarization inversion structures.

20. The optical waveguide device according to claim 19, wherein the optical waveguides are provided with the polarization inversion structures with different periods, respectively.

21. The optical waveguide device according to claim 18, further comprising reflectors at parts of the optical waveguides.

22. The optical waveguide device according to claim 18, wherein a line normal to a surface opposing the substrate in the emission parts of the optical waveguides and the surface of the substrate form an angle of about 45 degrees.

23. The optical waveguide device according to claim 18, wherein the phase matching conditions are those with respect to second harmonics.

24. The optical waveguide device according to claim 18, wherein the phase matching conditions are those with respect to a sum frequency.

25. The optical waveguide device according to claim 18, wherein the optical waveguides are optically coupled partially to one another.

26. An multiwavelength light source, comprising;

a plurality of coherent light sources with different wavelengths; and

an optical waveguide device, including a substrate, a plurality of optical waveguides formed in the vicinity of a surface of the substrate, injection parts formed at one end of the optical waveguides, and emission parts formed on the other end of the optical waveguides, the plurality of optical waveguides satisfying phase matching conditions different from one another, and the emission parts of the plurality of optical waveguides being provided at substantially the same position,

wherein the wavelengths of beams emitted from the coherent light sources are converted by the optical waveguide device.

27. The multiwavelength light source according to claim 26, wherein the coherent light sources are semiconductor lasers and the injection parts of the optical waveguide device and the semiconductor lasers are coupled directly.

28. The multiwavelength light source according to claim 26, wherein the coherent light sources with different wavelengths are multi-stripe semiconductor lasers formed on one substrate.

29. The multiwavelength light source according to claim 26, wherein the coherent light sources have a function for varying wavelengths.

30. The multiwavelength light source according to claim 26, wherein the optical waveguide device includes an electrode structure including electrodes and outputs are modulated by means of the electrodes.

31. An optical system, comprising:

a multiwavelength light source, including a plurality of coherent light sources with different wavelengths and an optical waveguide device, the optical waveguide device including a substrate, a plurality of optical waveguides formed in the vicinity of a surface of the substrate, injection parts formed at one end of the optical waveguides, and emission parts formed on the other end of the optical waveguides, the plurality of optical waveguides satisfying phase matching conditions different from one another, the emission parts of the plurality of optical waveguides being provided at substantially the same position, and wavelengths of beams from the coherent light sources being converted by the optical waveguide device; and

a focusing optical system.

32. The optical system according to claim 31, further comprising a wavelength filter,

wherein the wavelength filter separates beams from the multiwavelength light source.

33. The optical system according to claim 32, wherein the wavelength filter separates detected lights.

34. The optical system according to claim 31, wherein beams emitted from the multiwavelength light source are subjected to intensity modulations that are different according to their wavelengths.

35-50. -50. (canceled)