Magneto-optical recording and reproducing apparatus and method

A magneto-optical recording medium reproduction device for reproducing a signal from a magneto-optical recording medium with a recording layer and a reproducing layer comprising:

• laser means for oscillating a laser beam;
• optical means having an end surface adjacent to said magneto-optical recording medium, for irradiating said magneto-optical recording medium with the laser beam from said laser means via said end surface and receiving a laser beam reflected from said magneto-optical recording medium via said end surface;
• detection means for detecting the laser beam received by said optical means:;
• and
• magnetic field application means for applying an alternating field having a pulse width that ranges from 20 to 500 nsec to said magneto-optical recording medium to expand and shrink a domain created in said reproducing layer,
• wherein said optical means includes:
• a first optical fiber including a first core having a first diameter and a first refractive index, and a first clad formed around said first core and having a second refractive index smaller than said first refractive index;
• and
• a second optical fiber including a second core having a second diameter larger than said first diameter and a third refractive index, and a second clad formed around said second core and having a fourth refractive index smaller than said third refractive index.

A magneto-optical recording medium reproduction device for reproducing a signal from a magneto-optical recording medium with a recording layer and a reproducing layer, comprising:

• laser means for oscillating a laser beam;
• optical means having an end surface adjacent to said magneto-optical recording medium, for irradiating said magneto-optical recording medium with the laser beam from said laser means via said end surface and receiving a laser beam reflected from said magneto-optical recording medium via said end surface;
• detection means for detecting the laser beam received by said optical means;
• and
• magnetic field application means for applying an alternating field having a pulse width that ranges from 20 to 500 nsec to said magneto-optical recording medium to expand and shrink a domain created in said reproducing layer,
• wherein said optical means includes:
• a solid immersion lens having said end surface and a curved surface opposite to said end surface;
• an objective lens arranged on a said curved surface side of said solid immersion lens, coaxial with said solid immersion lens;
• and
• an optical system forming first laser beam with a first diameter and a second laser beam with a second diameter larger than said first diameter and allowing said first and second laser beams coaxially incident on said objective lens.

A magneto-optical recording medium reproduction device for reproducing a signal from a magneto-optic recording medium with a recording layer and a reproducing layer comprising:

• an optical fiber having one end surface adjacent to said magneto-optical recording medium and the other end surface;
• a laser arranged on the other end surface side of said optical fiber for providing a laser beam to the other end surface of said optical fiber;
• a photodetector arranged on the other end surface side of said optical fiber and receiving a laser beam from the other end surface of said optical fiber;
• and
• a magnetic head arranged for applying an alternating field having a pulse width that ranges from 20 to 500 nsec to said magneto-optical recording medium to expand and shrink a domain created in said reproducing layer,
• wherein said optical fiber includes:
• a core having a first refractive index;
• a first clad formed around said core and having a second refractive index smaller than said first refractive index;
• and
• a second clad formed around said first clad and having a third refractive index smaller than said second refractive index.

A magneto-optical recording medium reproduction device for reproducing a signal from a magneto-optical recording medium with a recording layer and a reproducing layer, comprising:

• a first optical fiber having one end surface adjacent to said magneto-optical recording medium and the other end surface;
• a laser arranged on the other end surface side of said first optical fiber for providing a laser beam to the other end surface of said first optical fiber;
• a second optical fiber having one end surface adjacent to said magneto-optical recording medium and the other end surface;
• a photodetector arranged on the other end surface side of said second optical fiber and receiving a laser beam from the other end surface of said second optical fiber;
• and
• a magnetic head arranged for applying an alternating field to said magneto-optical recording medium to expand and shrink a domain created in said reproducing layer.

A magneto-optical recording medium reproduction device for reproducing a signal from a magneto-optical recording medium with a recording layer and a reproducing layer, comprising:

• a solid immersion lens having a plane adjacent to said magneto-optical recording medium and a curved surface opposite to said plane;
• an objective lens arranged on the curved surface side of said solid immersion lens, coaxial with said solid immersion lens;
• a laser;
• an optical system for forming from a laser beam from said laser a first laser beam with a first diameter and a second laser beam with a second diameter larger than said first diameter and allowing said first and second laser beams coaxially incident on said objective lens;
• a photodetector receiving a laser beam reflected from said magneto-optical recording medium and transmitted through said solid immersion lens and said objective lens;
• and
• a magnetic head arranged for applying an alternating field to said magneto-optical recording medium to expand and shrink a domain created in said reproducing layer.

A magneto-optical recording medium reproduction device for reproducing a signal from a magneto-optical recording medium with a recording layer and a reproducing layer, comprising:

• a solid immersion lens having a plane adjacent to said magneto-optical recording medium and a curved surface opposite to said plane;
• an objective lens arranged on the curved surface side of said solid immersion lens, coaxial with said solid immersion lens;
• a first laser;
• a first lens forming a first laser beam with a first diameter, based on a laser beam from said first laser;
• a second laser;
• a second lens forming a second laser beam with a second diameter larger than said first diameter, based on a laser beam from said second laser;
• an optical system for allowing said first and second laser beams coaxially incident on said objective lens;
• a photodetector receiving a laser beam reflected from said magneto-optical recording medium and transmitted through said solid immersion lens and said objective lens;
• and
• a magnetic head arranged for applying an alternating field to said magneto-optical recording medium to expand and shrink a domain created in said reproducing layer.