Patent Publication Number: US-2010119194-A1

Title: Optical Waveguide With Reflector

Description:
BACKGROUND 
     Heat assisted magnetic recording (HAMR) requires that a thermal source be brought into close proximity to a magnetic writer. HAMR designs utilize an intense near field optical source to elevate the temperature of the storage media. When applying a heat or light source to the medium, it is desirable to confine the heat or light to the track where writing is taking place and to generate the write field in close proximity to where the medium is heated to accomplish high areal density recording. 
     A waveguide is an optical component that can provide for directing or guiding an electromagnetic wave. Data storage systems often incorporate optical components to assist in the recording of information. Such systems may include, for example, optical recording systems, magneto-optical recording systems or other thermal assisted type recording systems. There is an increased emphasis on improving the areal densities of data storage systems. Thus, all components of data storage systems are being improved and new components are being incorporated into data storage systems to achieve higher areal densities. 
     SUMMARY 
     An aspect of the present invention is to provide an optical waveguide that includes a core layer having a first core section and a second core section, wherein the first core section is non-axially aligned with the second core section. The optical waveguide also includes a cladding layer disposed about the core layer and a reflector in optical communication with the core layer for directing an electromagnetic wave from the first core section to the second core section. 
     Another aspect of the present invention is to provide an apparatus that includes a core layer for guiding an electromagnetic wave in a first propagation direction and a second propagation direction, a cladding layer disposed at least partially about the core layer, and a reflector in optical communication with the core layer for directing the electromagnetic wave from the first propagation direction to the second propagation direction. 
     A further aspect of the present invention is to provide an optical waveguide that includes a core layer for guiding an electromagnetic wave in a first direction and a second direction, a cladding layer disposed about the core layer, and means for directing the electromagnetic wave from the first direction to the second direction. 
     A further aspect of the present invention is to provide an apparatus that includes means for storing data, means for reading and/or writing data in association with the means for storing data, and an optical waveguide for guiding an electromagnetic wave to the means for reading and/or writing data, the optical waveguide including an internal reflector for changing the propagation direction of the electromagnetic wave. 
     These and various other features and advantages will be apparent from a reading of the following detailed description. 
    
    
     
       DRAWINGS 
         FIG. 1  is a pictorial representation of a system, in accordance with an aspect of the invention. 
         FIG. 2  is a plan view of an actuator arm, in accordance with an aspect of the invention. 
         FIG. 3  is an enlarged partial sectional view illustrating a waveguide of  FIG. 2 , in accordance with an aspect of the invention. 
         FIG. 4  is an enlarged partial sectional view illustrating a waveguide, in accordance with another aspect of the invention. 
         FIG. 5  is an enlarged partial sectional view illustrating a waveguide, in accordance with yet another aspect of the invention. 
         FIG. 6  is a schematic representation of a system, in accordance with an aspect of the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a pictorial representation of a system  10  that can include aspects of this invention. The system  10  includes a housing  12  (with the upper portion removed and the lower portion visible in this view) sized and configured to contain the various components of the system  10 . The system  10  includes a spindle motor  14  for rotating at least one disc  16  within the housing  12 . At least one actuator arm  18  is contained within the housing  12 , with each arm  18  having a first end  20  with a slider  22 , and a second end  24  pivotally mounted on a shaft by a bearing  26 . An actuator motor  28  is located at the arm&#39;s second end  24  for pivoting the arm  18  to position the slider  22  over a desired sector  27  of the disc  16 . The actuator motor  28  is regulated by a controller, which is not shown in this view and is well known in the art. 
       FIG. 2  is a plan view of an actuator arm  118  having a laser module  132  mounted thereon, in accordance with an aspect of the invention. The laser module  132  directs an electromagnetic wave  133  to an optical waveguide  140 . An optical component such as, for example, a lens  134 , may be positioned between the laser module  132  and the waveguide  140  to focus the wave  133 . The waveguide  140  is used to conduct, i.e. guide or direct, the electromagnetic wave  133  from the laser module  132  to a slider  122 . From the waveguide  140 , the electromagnetic wave  133  can be coupled into the slider  122  and directed onto an adjacent data storage medium for heating an area of the data storage medium (not shown in  FIG. 2 ). 
     As illustrated in  FIGS. 2 and 3 , the waveguide  140  includes at least one bend or turn, generally indicated by reference number  150 . The ability to bend or turn the waveguide  140  is desirable for when at least of a portion of the waveguide  140  needs to extend in more than one direction, i.e. at least a portion of the waveguide may extend non-linearly and/or from one plane to another plane. In one aspect, the waveguide  140  may be a flexible optical waveguide. 
     Referring to  FIG. 3 , the waveguide  140  includes a core layer  136  through which the electromagnetic wave  133  propagates. The core layer  136  may be formed of, for example, polymethylmethacrylate, polystyrene, polycarbonate, SU8 or silicone polymers such as polysiloxanes or siloxanes. High index of refraction particles may be added to the waveguide material to adjust the index of refraction of the material. The waveguide  140  also includes a cladding layer  138  that is at least partially disposed about the core layer  136 . The cladding layer  138  may be formed of, for example, polymethylmethacrylate, polystyrene, polycarbonate, SU8 or silicone polymers such as polysiloxanes or siloxanes. 
     As illustrated in  FIG. 3 , the waveguide  140  includes a reflector  160  that is positioned in optical communication with the with the core layer  136  for directing the electromagnetic wave  133  from a first core section  136   a  of the core layer  136  to a second core section  136   b  of the core layer  136 . In one aspect, the core layer  136  is continuous from the first core section  136   a  to the second core section  136   b.  In one aspect, the first core section  136   a  is non-axially aligned with the second core section  136   b  and, thus, the reflector is positioned for redirecting the electromagnetic wave  133 . For example, the electromagnetic wave  133  may have a first segment, generally identified as  133   a , which propagates in a first direction within the first core section  136   a  that is redirected by the reflector  160  to propagate in a second direction, as generally indicated by a second segment  133   b  of the wave  133 , within the second core section  136   b.    
     The reflector  160  can be, for example, a trench  162  that is formed by etching a trench  162  into the waveguide  140 , stamping a trench  162  into the waveguide  140  or molding the waveguide  140  with a trench  162  in the mold. In one aspect, the reflector  160  may be an empty trench  162 , i.e. filled with only air, such that it will reflect the electromagnetic wave  133  with a waveguide-air interface and, thus, the trench  162  does not need to be filled in order to function as a reflector for redirecting or guiding the wave  133 . 
     In another aspect, the trench  162  may be filled to keep it from collecting particles and reducing the reflectivity over the life-time of the waveguide  140 . For example, the reflector  160  can be formed using metals (e.g., Au, Ag, Al, Cu, Cr), metal oxide dielectrics (e.g., SiO2, Ta2O5, Al2O3, Si3N4, SiON, AlON, TiO2), dielectric polymers (e.g., polymethylmethacrylate, polystyrene, polycarbonate, SU8 or silicone polymers such as polysiloxanes or siloxanes) porous materials (e.g., any of the waveguide materials can be fabricated with voids to adjust the index of refraction of the material), metal colloid polymers (e.g., particles may be added to any of the waveguide materials to adjust the index of refraction of the material), or any combinations of these materials. An advantage of the polymer option would be its physical flexibility. In one aspect, metal or dielectric particles could be mixed with the polymer to form a colloid to achieve the appropriate optical properties. 
     In one aspect of the invention as shown, for example, in  FIG. 3 , the reflector  160  may be positioned at least partially in the core layer  136 . In another aspect of the invention, the reflector  160  may be positioned at least partially in the cladding layer  138 . The positioning of the reflector  160  within the waveguide  140  is chosen to provide the desired optimum redirecting of the electromagnetic wave  133 . 
       FIG. 4  illustrates a waveguide  240  that includes at least one bend or turn, generally indicated by reference number  250 , in accordance with another aspect of the invention. The waveguide  240  includes a core layer  236  through which the electromagnetic wave  333  propagates. The waveguide  240  also includes a cladding layer  238  that is at least partially disposed about the core layer  236 . The waveguide  240  further includes a diffraction grating  260  which serves as a reflector. Specifically, the grating  260  is positioned in optical communication with the with the core layer  236  for directing the electromagnetic wave  233  from a first core section  236   a  of the core layer  236  to a second core section  236   b  of the core layer  236 . In one aspect, the core layer  236  is continuous from the first core section  236   a  to the second core section  236   b.  In one aspect, the first core section  236   a  is non-axially aligned with the second core section  236   b  and, thus, the grating  260  is positioned for redirecting the electromagnetic wave  233 . For example, the electromagnetic wave  233  may have a first segment, generally identified as  233   a , which propagates in a first direction within the first core section  236   a  that is redirected by the grating  260  to propagate in a second direction, as generally indicated by a second segment  233   b  of the wave  233 , within the second core section  236   b.    
       FIG. 5  illustrates a waveguide  340  that includes at least one bend or turn, generally indicated by reference number  350 , in accordance with another aspect of the invention. The waveguide  340  includes a core layer  336  through which the electromagnetic wave  333  propagates. The waveguide  340  also includes a cladding layer  338  that is at least partially disposed about the core layer  336 . The waveguide  340  further includes a photonic crystal reflector  360 . Specifically, the photonic crystal reflector  360  is positioned in optical communication with the with the core layer  336  for directing the electromagnetic wave  333  from a first core section  336   a  of the core layer  336  to a second core section  336   b  of the core layer  336 . In one aspect, the core layer  336  is continuous from the first core section  336   a  to the second core section  336   b.  In one aspect, the first core section  336   a  is non-axially aligned with the second core section  336   b  and, thus, the photonic crystal reflector  360  is positioned for redirecting the electromagnetic wave  333 . For example, the electromagnetic wave  333  may have a first segment, generally identified as  333   a , which propagates in a first direction within the first core section  336   a  that is redirected by the photonic crystal reflector  360  to propagate in a second direction, as generally indicated by a second segment  333   b  of the wave  333 , within the second core section  336   b.    
       FIG. 6  is a schematic representation of a system, in accordance with an aspect of the invention. Specifically, a slider  122  (such as shown, for example, in  FIG. 2 ) includes a waveguide transducer  170  formed on an end thereof. The waveguide transducer  170  includes a core layer  172  through which an electromagnetic wave propagates. The waveguide  170  also includes a cladding layer  174  that is at least partially disposed about the core layer  172 . The waveguide  170  further includes a diffraction grating  176  for coupling the electromagnetic wave  133  into the core layer  172 . 
     Still referring to  FIG. 6 , the system also includes the waveguide  140  that includes the core layer  336  through which the electromagnetic wave  333  propagates and the cladding layer  138  that is at least partially disposed about the core layer  136 . The waveguide  140  also includes a first reflector  160   a  and a second reflector  160   b  that are positioned in optical communication with the core layer  136  for directing the electromagnetic wave  133  toward the grating  176 . It will be appreciated that additional reflectors can be provided in the waveguide  140  for directing or guiding the wave  133  in more than one direction, i.e. non-linearly and/or from one plane to another plane, as desired. 
     The implementation described above and other implementations are within the scope of the following claims.