Flying type optical head integrally formed with light source and photodetector and optical disk apparatus with the same

Abstract

The optical head is arranged such that a semiconductor laser and a photodetector are formed via a buffer layer on the same substrate; and an opening portion is formed in the substrate under the semiconductor laser and the photodetector. This optical head is further arranged by that the opening portion is filled with a first transparent layer; a diffraction grating is formed on a lower surface of the first transparent layer; a second transparent layer is stacked on a lower surface of the first transparent layer; and a condenser lens is formed on a lower surface of the transparent layer. In this optical head, laser light emitted from the semiconductor laser is penetrated through the substrate, the first transparent layer, the diffraction grating, and the second transparent layer, and condensed toward a place just under the condenser lens by the condenser lens, thereby forming a light spot on an optical storage medium positioned apart from the condenser lens, whereas reflection light reflected from the optical storage medium is penetrated through the condenser lens and the second transparent layer, diffracted by the diffraction grating toward a light receiving plane of the photodetector, and further penetrated through the first transparent layer to be received by the photodetector.

What is claimed is:  
     
         1 . An optical head: wherein 
 a semiconductor laser and a photodetector are formed via a buffer layer on the same substrate, and an opening portion is formed in the substrate under said semiconductor laser and said photodetector; wherein    said opening portion is filled with a first transparent layer; wherein    a diffraction grating is formed on a lower surface of said first transparent layer; wherein    a second transparent layer is stacked on a lower surface of said first transparent layer; and wherein    a condenser lens is formed on a lower surface of said transparent layer, in which laser light emitted from said semiconductor laser is penetrated through said substrate, said first transparent layer, and condensed toward a place just under the condenser lens by said condenser lens, thereby forming a light spot on an optical storage medium positioned apart from said condenser lens, a reflection light reflected from said optical storage medium is penetrated through said condenser lens and said second transparent layer, diffracted by said diffraction grating toward a light receiving plane of said photodetector, and further penetrated through said first transparent layer to be received by said photodetector.    
     
     
         2 . An optical head as claimed in    claim 1   , wherein said semiconductor laser is a surface emitting laser.  
     
     
         3 . An optical head as claimed in    claim 2   , wherein said semiconductor laser is a mesa type semiconductor laser.  
     
     
         4 . An optical head as claimed in    claim 1   , wherein two groups of photodetectors are formed, and wherein two polarizers positioned perpendicular to each other are provided between said first transparent layer and the substrate under the light receiving surface of the photodetector of the respective groups.  
     
     
         5 . An optical head as claimed in    claim 1   , wherein a ceramic film is formed on the lower portion of the transparent layer on which said condenser lens except for the portion of the condenser lens.  
     
     
         6 . An optical head as claimed in    claim 5   , wherein a thin film coil is provided at a portion of said ceramic film.  
     
     
         7 . An optical head as claimed in    claim 5   , wherein a shape of said optical head is processed to become a flying slider shape.  
     
     
         8 . An optical head as claimed in    claim 7   , wherein a flying amount is below than 20 micrometers.  
     
     
         9 . A method of manufacturing an optical head wherein a semiconductor laser and a photodetector are formed via a buffer layer on the same substrate in such a manner that a laser light emitting surface of the semiconductor laser and a light receiving surface of said photodetector are directed to the same direction, and an opening is fabricated under said laser emitting surface and said light receiving surface by an etching process, comprising the steps of: 
 stacking a first transparent layer used to fill said opening by way of the plasma CVD (chemical vapor deposition) and sputtering processes;    forming a diffraction grating on a lower surface of said first transparent layer by way of the photomask exposure process;    stacking a second transparent layer under said first transparent layer by way of the plasma CVD, and sputtering processes; and    forming either a grating lens on a lower surface of said second transparent layer by way of the photomask exposure process, or one of a distributed index lens and a convex lens on said lower surface of said second transparent layer by way of the disk apparatus.    
     
     
         10 . An optical disk apparatus comprising: 
 a flying type optical head whose flying amount is smaller than, or equal to 26 micrometers;    an optical disk having no transparent protection layer on the information reading side of the recording surface thereof, or having a transparent protection layer with a thickness less than a value obtained by subtracting said flying amount from a back focus distance of an object lens located within a medium whose refractive index is 1.0, and by multiplying the subtraction result by a refractive index of a protection layer;    a supporting mechanism for supporting said optical head; and    a dust-guard cartridge for containing at least said optical disk, said optical head, and said supporting mechanism.    
     
     
         11 . An optical disk apparatus comprising: 
 an optical disk having no transparent protection layer at the information reading side of the recording surface thereof, or having a transparent protection layer with a thickness less than 26 micrometers;    a supporting mechanism for supporting said optical head; and    a dust-guard cartridge for containing said optical disk, said flying type optical head, and said supporting mechanism.    
     
     
         12 . A method of manufacturing an optical head in which a surface emitting laser and a photodiode are manufactured at the same time in accordance with the following processing steps (a) to (f), comprising the steps wherein: 
 (a) an n type AlGaAs buffer layer is grown on an n type GaAs substrate, an n+ type GaAs layer is grown on said buffer layer, and a first reflection mirror layer constructed by alternately stacking n type AlAs layers and GaAlAs layers is formed on said n+ type GaAs layer;    (b) said first reflection mirror layer is removed by way of an etching process only from a portion where said photodiode is to be manufactured, and an n type AlGaAs layer is grown on the layer removed portion;    (c) an n type AlGaAs clad layer is formed on said first reflection mirror layer and said n type AlGaAs layer, a p type GaAlAs quantum well layer is grown on said clad layer as an activate layer, a p type GaAlAs clad layer is fabricated on said activate layer, and a second reflection mirror layer constructed by alternately sacking n type AlAs layers and GaAlAs layers is grown on said clad layer;    (d) said second reflection mirror layer is removed by way of the etching process only from the portion where the photodiode is to be formed, and a p type GaAs layer is formed on the removed portion;    (e) a p+ type GaAs layer is formed on said second reflection mirror layer and said p type GaAs layer, on which an Au electrode is formed; and    (f) a groove for separating said surface emitting laser from said photodiode is formed.    
     
     
         13 . An optical head: wherein 
 a semiconductor laser is formed via a buffer layer on a substrate, and an opening portion is fabricated in the substrate at a lower portion of a laser emitting surface; wherein    said opening portion is furthermore filled with a transparent layer; and wherein    one of a grating lens, a distributed index lens, and a condenser lens made of a convex lens having a diameter less than 1 mm is formed on a lower surface of said transparent layer.    
     
     
         14 . An optical disk high-density storage apparatus including a means for reading and writing information, comprising: 
 an air-flying head equipped with a very small mirror facing to an optical disk, and capable of flying on a surface of the optical disk; and    an optical system including a laser light irradiating means and a photodetecting means, whereby the laser light is irradiated from a rear surface of said optical disk to a region containing at least a region overlapped with said very small mirror of said optical disk, thereby reading the information stored in said optical disk.    
     
     
         15 . An optical disk high-density storage apparatus as claimed in    claim 14   , wherein a width of said very small mirror is smaller than a spot diameter of said laser light irradiated onto said optical disk.  
     
     
         16 . An optical disk high-density storage apparatus as claimed in    claim 15   , wherein a magnetic domain which is located just under said very small mirror and is present in a portion limited to the region onto which the laser light is irradiated, is detect by said photodetecting means arranged at a rear side of the optical disk by utilizing either the Faraday effect, or the Kerr effect.  
     
     
         17 . An optical disk high-density storage apparatus as claimed in    claim 14   , wherein said air-flaying head owns an information writing magnetic pole; and wherein 
 said very small mirror is a mirror of said magnetic pole.    
     
     
         18 . An optical disk high-density storage apparatus as claimed in    claim 14   , wherein said head owns an information writing magnetic pole; and wherein 
 said magnetic domain is written by inverting a polarity of said information writing magnetic pole.    
     
     
         19 . An optical disk high-density storage apparatus as claimed in    claim 14   , wherein information is written into a region containing at least a region overlapped with said very small mirror of the optical disk, while the laser light is irradiated onto said region from a rear surface of said optical disk.  
     
     
         20 . An optical disk high-density storage apparatus as claimed in    claim 14   , wherein said head has an information writing magnetic pole; and wherein 
 said magnetic domain is written into a region of said optical disk onto which the laser light is irradiated to increase a temperature of said region, and which is located just under said magnetic pole due to the thermomagnetic phenomenon.    
     
     
         21 . An optical disk high-density storage apparatus as claimed in    claim 14   , wherein said head owns an information writing magnetic pole; and wherein 
 said magnetic pole is used as a mirror for reflecting the laser light from the rear surface of said optical head, and also a magnetizing polarity of said magnetic pole is inverted in response to an information stream, whereby a magnetic domain corresponding to information of “1” and “0” is written into a region of said optical disk which is located just under said magnetic pole and onto which the laser light is irradiated.    
     
     
         22 . An optical disk high-density storage apparatus as claimed in    claim 14   , wherein a plurality of information writing magnetic poles are arranged within a single head along a direction substantially normal to a relative moving direction between said optical disk and said head; and wherein 
 a plurality of information is written by inverting magnetizing polarities of said plural magnetic poles in correspondence with an arbitrary information stream, while said plural information is converted into parallel presence of the magnetic poles.    
     
     
         23 . An optical disk high-density storage apparatus as claimed in    claim 14   , wherein a plurality of information writing magnetic poles are arranged within a single head along a direction substantially normal to a relative moving direction between said optical disk and said head; and wherein 
 under such a condition that common laser light which is partially overlapped with all of said plural magnetic poles, is irradiated from a rear surface of the optical disk onto the optical disk, a plurality of information is written by inverting magnetizing polarities of said plural magnetic poles in correspondence with an arbitrary information stream, while said plural information is converted into parallel presence of the magnetic poles.    
     
     
         24 . An optical disk high-density storage apparatus as claimed in    claim 14   , wherein a plurality of said very small mirrors are positionally shifted along the relative moving direction between said optical disk and said head; and wherein 
 a plurality of information which has been written into a region located just under said plurality of very small mirrors and onto which the laser light is irradiated, is detected by the photodetecting means, while common laser light which is partially overlapped with at least all of said plurality of very small mirrors, is irradiated from the rear surface to the optical disk.    
     
     
         25 . An optical disk high-density storage apparatus as claimed in    claim 14   , wherein said plurality of information is separated from each other and detected based on both of an output from said photodetecting means and change timings of said output.  
     
     
         26 . An optical disk high-density storage apparatus as claimed in    claim 14   , wherein said head is equipped with a reading very small mirror and either a writing magnetic pole, or a writing very small mirror; and wherein 
 said reading very small mirror and either said writing magnetic pole, or said writing very small mirror are positioned apart from each other by an equal radial distance with respect to a rotation center of said optical disk.    
     
     
         27 . An optical disk high-density storage apparatus as claimed in    claim 14   , wherein either said very small mirror, or said magnetic pole having the function of said very small mirror is constructed by a sectional plane of a metal film laminated on a plane substrate.