Optical head and apparatus for recording and reproducing optical information through the use of the optical head

• US 6,272,097 B1
• Filed: 05/18/1999
• Issued: 08/07/2001
• Est. Priority Date: 05/19/1998
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Shimano, Takeshi, Tanaka, Toshiaki, Nakamura, Shigeru, Nakao, Takeshi
• Primary Examiner(s): Young, W. R.
• Application Number:
  US09/313,211
• Time in Patent Office: 812 Days
• Field of Search: 369/44.12, 369/44.23, 369/112.02, 369/112.05, 369/112.08, 369/112.09, 369/112.13, 369/112.14, 369/112.2, 369/112.21, 369/112.23, 369/112.25, 369/112.27, 369/120-122
• US Class Current: 369/112.08
• CPC Class Codes: G11B 11/1058 Flying heads
• CPC Class Codes: G11B 7/122 Flying-type heads, e.g. analogous to Winchester type in magnetic recording
• CPC Class Codes: G11B 7/124 the integrated head arrangements including waveguides
• CPC Class Codes: G11B 7/1365 Separate or integrated refractive elements, e.g. wave plates
• CPC Class Codes: G11B 7/1372 Lenses
• CPC Class Codes: G11B 7/22 Apparatus or processes for the manufacture of optical heads, e.g. assembly

Abstract

A minute optical head is provided so that a light source and one or more photo detector elements are integrated on the same substrate by a simple manufacturing process and may be applied to an apparatus for recording and reproducing recordable optical information. An apparatus for recording and reproducing optical information is arranged to have a minute optical head. A light waveguide layer composed of column semiconductor crystal is formed on a monocrystalline transparent substrate and an active layer is formed on the side of the light waveguide layer. The light beam source is a semiconductor having a vertical resonator formed of a high-reflection film before and after an emitting surface of the active layer so that a light beam is vertically radiated to the substrate. The photo detector element is integrated on the closer portion of the substrate to the light beam source of the semiconductor laser. Further, on the opposed surface of the substrate to the light beam source are sequentially integrated a first transparent layer, a diffraction grating, a second transparent layer, a phase difference generating element, a third transparent layer, a light beam focusing element, a fourth transparent layer, and a slide-resisting protective layer. The slide-resisting protective layer is located closer to and as opposed to the information recording medium.

Claims

1. An optical head comprising:

a light beam source;

a light beam focusing element for focusing and applying a light beam radiated from said light beam source onto an information recording medium;

a phase difference generating element for generating a predetermined phase difference to a light beam from said light beam source and the light beam reflected on said information recording medium;

a light beam separating element for separating the light beam reflected on said information recording medium into fluxes of light;

one or more photo detector elements for detecting an information signal recorded on said information recording medium in response to said reflected light; and

wherein said light beam source is integrated on the same substrate as said photo detector element and said light beam source is a semiconductor laser having a vertical resonator formed against a light waveguide structure having an active layer on the side of semiconductor crystal vertically formed on said substrate.

2. The optical head as claimed in claim 1, wherein said photo detector element is integrated on the same side of said substrate as said light beam source.

3. The optical head as claimed in claim 2, wherein the light beam radiated from said light beam source is passed through said substrate and then is applied and focused onto said information recording medium.

4. The optical head as claimed in claim 1, wherein said photo detector element is integrated on the opposed side of said substrate to said light source.

5. The optical head as claimed in claim 4, wherein the light beam radiated from said light beam source is passed through said substrate and then is applied and focused onto said information recording medium.

6. The optical head as claimed in claim 1, wherein said light beam separating element and said phase difference generating element and said focusing element are integrated on the opposed surface of said substrate to said light source.

7. The optical head as claimed in claim 6, wherein said light beam separating element is a diffraction grating.

8. The optical head as claimed in claim 6, wherein the phase difference generated by said phase difference generating element is a quarter of a wavelength and an optical axis of said phase difference generating element is set about 45 degrees with respect to an active layer of said semiconductor laser.

9. The optical head as claimed in claim 6, wherein said focusing element is a grating lens, a index-distributed type lens, or a convex lens.

10. The optical head as claimed in claim 6, wherein said focusing element is a grating lens, the optical path from said grating lens to a focused spot of a light beam is made of a solid material, said focused spot of the light beam is formed near the surface of said solid material located close to and as opposed to said information recording medium, and the effective numeric aperture given by said grating lens is one or more.

11. The optical head as claimed in claim 6, wherein said light focusing element is composed of a grating lens and a semispheric lens, said semispheric lens is located to be convex on the side of said light source, and a synthesized numeric aperture of said grating lens and said semispheric lens is one or more.

12. The optical head as claimed in claim 1, wherein said substrate is a sapphire (a-Al₂O₃) substrate or silicon carbide (a-SiC) substrate.

13. The optical head as claimed in claim 1, wherein a slide-resisting protective film having a slide-resisting function is formed on the opposed side of said light focusing element to said information recording medium, excepting the portion where a light beam is focused.

14. The optical head as claimed in claim 13, wherein said slide-resisting protective film is made of ceramics.

15. The optical head as claimed in claim 13, wherein a filmy electromagnetic coil is formed on said slide-resisting protective film.

16. The optical head as claimed in claim 1, wherein said optical head is mounted on a flying slider.

17. The optical head as claimed in claim 16, wherein the flying amount is 1 μ

m or less.

18. The optical head as claimed in claim 1, wherein said light beam separating element and said phase difference generating element are integrated at a given interval and on the opposed side of said substrate to said light source and the integrated matter is located separately from said focusing element.

19. The optical head as claimed in claim 18, wherein said light focusing element is a grating lens, a index-distributed type lens, or a convex lens.

20. The optical head as claimed in claim 1, wherein said light beam separating element, said phase difference generating element and said focusing element are located on the opposed side of said substrate to said light source and separately from said substrate.

21. The optical head as claimed in claim 20, wherein said focusing element is a grating lens, a index-distributed type lens, or a convex lens.

22. An apparatus for recording and reproducing optical information comprising:

an optical head having a light beam source, a light beam focusing element for focusing and applying a light beam radiated from said light source onto an information recording medium, a phase difference generating element for generating a predetermined phase difference to a ray of light from said beam source and the light reflected on said information recording medium, a light beam separating element for separating the light beam reflected on said information recording medium into light beams, one or more photo detector elements for detecting an information signal recorded on said information recording medium in response to said reflected light, said light beam source being integrated on the same substrate as said photo detector element and said light beam source being a semiconductor laser having a vertical resonator formed against a light waveguide structure having an active layer on the side of semiconductor crystal vertically formed on said substrate;

a mechanism for supporting said optical head;

a disk-like information recording medium;

a mechanism for rotating and supporting said information recording medium; and

a dust-proof case for accommodating said supporting mechanism, said information recording medium, and said rotating mechanism.

23. The apparatus as claimed in claim 22, wherein said optical head is located on the opposed side of an information recording film formed on said information recording medium to a substrate of said information recording medium and a light beam radiated from said light beam source is applied and focused onto said information recording film without passing through the substrate of said information recording medium.

24. The apparatus as claimed in claim 22, wherein said optical head is arranged so that said light beam separating element and said phase difference generating element are integrated at a given interval and on the opposed side of said optical head to said light beam source with respect to said substrate and the integrated matter is located separately from said focusing element.

25. The apparatus as claimed in claim 22, wherein said optical head is arranged so that said light beam separating element and said phase difference generating element and said focusing element are located on the opposed side of said substrate to said light beam source and separately from said substrate.