Surface plasmon lens for heat assisted magnetic recording

Abstract

An apparatus for focusing plasmon waves to a spot. The plasmon waves are there converted to light. In one application, the light is used for heat induced magnetic recording. In another application, the light is used as a part of near field scanning microscope. The plasmon waves may be induced on a converging rectangular cone having an aperture. The plasmon waves may also be focused on a flat surface by a curved dielectric lens. In the heat induced magnetic recording embodiment, a magnetic pole structure is integrated into the focusing apparatus, either as one surface of the rectangular cone, or as a layer upon which the curved dielectric lens is formed.

I claim:  
     
         1 . Apparatus for focusing plasmon waves comprising: 
 a metallic layer;    a first dielectric layer having a first index of refraction;    a second dielectric layer having a second index of refraction higher than the first index of refraction; and    the metallic layer and the first and second dielectric layers arranged to focus to a spot plasmon waves induced at the interface between the metallic and first dielectric layers in response to light incident on the second dielectric layer.    
     
     
         2 . Apparatus according to  claim 1  wherein said metallic layer has a structure that converges to an aperture and wherein said spot is co-located with said aperture.  
     
     
         3 . Apparatus according to  claim 2  wherein said metallic layer and said first and second dielectric layers form a rectangular cone.  
     
     
         4 . Apparatus according to  claim 3  wherein one side of said rectangular cone further comprises a magnetic recording pole.  
     
     
         5 . Apparatus according to  claim 1  wherein said metallic layer is selected from a group comprising gold or silver or aluminum or copper.  
     
     
         6 . Apparatus according to  claim 1  wherein said first dielectric layer is selected from a group consisting of air, MgF 2 , SiO 2 , SiN or Al 2 O 3 .  
     
     
         7 . Apparatus according to  claim 1  wherein said second dielectric layer is selected from a group consisting of SiO 2 , Al 2 O 3 , silicon, SiN, Ta 2 O 5 , TiO 2 , GaP or ZnS.  
     
     
         8 . Apparatus according to  claim 1  further including a protective layer affixed to said metallic layer opposite said first dielectric layer.  
     
     
         9 . Apparatus according to  claim 4  wherein said magnetic recording pole is composed of a magnetically permeable material.  
     
     
         10 . Apparatus according to  claim 1  wherein: 
 said metallic layer comprises a thin film;  
 said first dielectric layer is arranged on a first side of said metallic layer; and  
 said second dielectric layer is arranged on the opposite side of said metallic thin film from said first dielectric layer.  
 
     
     
         11 . Apparatus according to  claim 10  further comprising: 
 a third dielectric layer arranged on the same side of the metallic layer as the first dielectric layer, the third dielectric layer having a third index of refraction greater than said first index of refraction on the first dielectric layer, the third dielectric layer have a curved surface that is arranged to focus the plasmon waves on said spot.  
 
     
     
         12 . Apparatus according to  claim 11  further comprising a magnetic pole layer arranged in a layer perpendicular to said metallic layer; said magnetic pole layer running through said spot.  
     
     
         13 . Apparatus according to  claim 12  wherein said metallic layer, said third dielectric layer and said magnetic pole all terminate in a third, substantially flat surface running through said focal point spot.  
     
     
         14 . Apparatus according to  claim 13  wherein said metallic layer and said first, second and third dielectric layers are all arranged on only on side of said magnetic pole layer.  
     
     
         15 . Apparatus according to  claim 10  wherein the metallic layer has a region of different thickness arranged on the same side of the metallic layer as the first dielectric layer in the path of induced plasmon waves, the thinner metallic region having an index of refraction higher than the thicker metallic region, the interface between the two regions having a curvature that is arranged to focus the plasmon waves on said spot.  
     
     
         16 . Apparatus for focusing plasmon waves on a spot, comprising: 
 means for inducing plasmon waves on a metallic surface; and    means for focusing the plasmon waves to a spot.    
     
     
         17 . Apparatus according to  claim 16  further including, means for converting the plasmon waves at the spot into light.