Plastic optical fiber with a lens portion, optical fiber connector, and connecting structures and methods between optical fibers and between optical and light emitting/receiving device

Abstract

A plastic optical fiber with a lens portion includes a plastic optical fiber with a concave portion formed on its end face, and a lens portion having a function of controlling light rays. The lens portion is formed of a refractive index adjusting material filled in the concave portion and having a refractive index different from a refractive index of the plastic optical fiber.

What is claimed is:  
     
         1 . A plastic optical fiber with a lens portion comprising: 
 a plastic optical fiber, a concave portion being formed on an end face of said plastic optical fiber; and    a lens portion having a function of controlling light rays, said lens portion being formed of a refractive index adjusting material filled in said concave portion and having a refractive index different from a refractive index of said plastic optical fiber.    
     
     
         2 . The plastic optical fiber with a lens portion according to  claim 1 , wherein said concave portion has a rotation-symmetrical shape about an optical axis of said plastic optical fiber.  
     
     
         3 . The plastic optical fiber with a lens portion according to  claim 2 , wherein said concave portion has a spherical shape about an optical axis of said plastic optical fiber.  
     
     
         4 . The plastic optical fiber with a lens portion according to  claim 1 , wherein said refractive index adjusting material has a refractive index larger than the refractive index of said plastic optical fiber so that said lens portion is a light-condensing lens portion.  
     
     
         5 . The plastic optical fiber with a lens portion according to  claim 1 , wherein said refractive index adjusting material comprises a curable material.  
     
     
         6 . The plastic optical fiber with a lens portion according to  claim 1 , wherein an outer surface of said refractive index adjusting material filled in said concave portion is substantially flat.  
     
     
         7 . The plastic optical fiber with a lens portion according to  claim 1 , wherein an outer surface of said refractive index adjusting material filled in said concave portion is substantially spherical.  
     
     
         8 . The plastic optical fiber with a lens portion according to  claim 1 , wherein a flat portion is formed around said concave portion on the end face of said plastic optical fiber.  
     
     
         9 . A plastic optical fiber with a lens portion comprising: 
 a plastic optical fiber;    a concave portion, said concave portion being formed on an end face of said plastic optical fiber and having a function of controlling light rays; and    a flat portion, said flat portion being formed around said concave portion on the end face of said plastic optical fiber.    
     
     
         10 . A plastic optical fiber with a lens portion comprising: 
 a plastic optical fiber, a concave portion being formed on an end face of said plastic optical fiber; and    a lens portion having a function of controlling light rays, said lens portion being formed of a refractive index adjusting material filled in said concave portion and having a refractive index larger than a refractive index of said plastic optical fiber.    
     
     
         11 . The plastic optical fiber with a lens portion according to  claim 10 , wherein said concave portion has a rotation-symmetrical shape about an optical axis of said plastic optical fiber.  
     
     
         12 . The plastic optical fiber with a lens portion according to  claim 11 , wherein said concave portion has a spherical shape about an optical axis of said plastic optical fiber.  
     
     
         13 . The plastic optical fiber with a lens portion according to  claim 10 , wherein said refractive index adjusting material comprises a curable material.  
     
     
         14 . The plastic optical fiber with a lens portion according to  claim 10 , wherein an outer surface of said refractive index adjusting material filled in said concave portion is substantially flat.  
     
     
         15 . The plastic optical fiber with a lens portion according to  claim 10 , wherein an outer surface of said refractive index adjusting material filled in said concave portion is substantially spherical.  
     
     
         16 . The plastic optical fiber with a lens portion according to  claim 10 , wherein a flat portion is formed around said concave portion on the end face of said plastic optical fiber.  
     
     
         17 . A connecting structure for connecting optical fibers comprising: 
 a plastic optical fiber with a concave portion formed on an end face of said plastic optical fiber, said plastic optical fiber including a core and a cladding; and    an optical fiber, said optical fiber including a core and a cladding, and said optical fiber being different from said plastic optical fiber in at least one of a numerical aperture and a diameter of said core;    wherein said plastic optical fiber and said optical fiber are arranged with their end faces opposed to each other, with a spacing interposed between their end faces, and optically coupled to each other.    
     
     
         18 . The connecting structure for connecting optical fibers according to  claim 17 , wherein said plastic optical fiber is larger than said optical fiber in at least one of the numerical aperture and a core diameter.  
     
     
         19 . The connecting structure for connecting optical fibers according to  claim 17 , wherein said concave portion of said plastic optical fiber is filled with a filler having a refractive index larger than a refractive index of said core of said optical fiber.  
     
     
         20 . The connecting structure for connecting optical fibers according to  claim 19 , wherein said filler is curable.  
     
     
         21 . The connecting structure for connecting optical fibers according to  claim 17 , wherein said concave portion of said plastic optical fiber and its surroundings are filled with a filler having a refractive index larger than a refractive index of said core of said optical fiber.  
     
     
         22 . The connecting structure for connecting optical fibers according to  claim 21 , wherein said filler is non-curable.  
     
     
         23 . The connecting structure for connecting optical fibers according to  claim 17 , wherein said concave portion and its surroundings are filled with air or gas whose refractive index is smaller than a refractive index of said core of said plastic optical fiber, and said plastic optical fiber and said optical fiber are optically coupled to transmit light from said optical fiber to said plastic optical fiber.  
     
     
         24 . The connecting structure for connecting optical fibers according to  claim 17 , wherein a flat portion is formed around said concave portion on the end face of said plastic optical fiber.  
     
     
         25 . The connecting structure for connecting optical fibers according to  claim 24 , wherein said flat portion is caused to abut a spacer such that said plastic optical fiber is aligned in an optical-axial direction.  
     
     
         26 . An optical fiber connector comprising: 
 a plastic optical fiber with a concave portion formed on an end face of said plastic optical fiber, said plastic optical fiber including a core and a cladding;    an optical fiber with a core and a cladding, said optical fiber being different from said plastic optical fiber in at least one of a numerical aperture and a diameter of said core;    a first ferrule for holding said plastic optical fiber;    a second ferrule for holding said optical fiber; and    a housing member for housing said first ferrule and said second ferrule to arrange said plastic optical fiber and said optical fiber with their inner end faces opposed to each other and a spacing formed between their inner end faces, and optically couple said plastic optical fiber and said optical fiber.    
     
     
         27 . The optical fiber connector according to  claim 26 , wherein said housing member comprises a pair of semicylindrical split sleeves.  
     
     
         28 . The optical fiber connector according to  claim 26 , wherein said housing member comprises an integral cylindrical member.  
     
     
         29 . The optical fiber connector according to  claim 26 , wherein outer end faces of said plastic optical fiber and said optical fiber are formed to lie in said housing member.  
     
     
         30 . The optical fiber connector according to  claim 26 , wherein outer end faces of said plastic optical fiber and said optical fiber are formed to lie on a plane which contains an end face of said housing member.  
     
     
         31 . The optical fiber connector according to  claim 26 , wherein outer end faces of said plastic optical fiber and said optical fiber are formed non-parallel with an end face of said housing member.  
     
     
         32 . The optical fiber connector according to  claim 26 , wherein outer end faces of said plastic optical fiber and said optical fiber are formed uneven.  
     
     
         33 . The optical fiber connector according to  claim 26  further comprising connecting means for optically connecting an optical device to said optical fiber, said connecting means being provided on at least one of opposite end faces of said housing member.  
     
     
         34 . The optical fiber connector according to  claim 26 , wherein outer end faces of said plastic optical fiber and said optical fiber are formed to lie outside an end face of said housing member.  
     
     
         35 . The optical fiber connector according to  claim 26  further comprising a filler filled in the spacing.  
     
     
         36 . The optical fiber connector according to  claim 26  further comprising a spacer contained in said housing member and inserted between inner end faces of said plastic optical fiber and said optical fiber.  
     
     
         37 . A method of connecting optical fibers comprising: 
 preparing a plastic optical fiber with a concave portion formed on its end face, and a second optical fiber;    filling the concave portion of the plastic optical fiber with a refractive index adjusting material;    positioning end faces of the plastic optical fiber and the second optical fiber in opposition to each other; and    bonding the end faces of the plastic optical fiber and the second optical fiber to each other to optically couple the plastic optical fiber and the second optical fiber.    
     
     
         38 . The connecting method according to  claim 37 , wherein the second optical fiber prepared in said preparing step is also a plastic optical fiber with a concave portion formed on its end face, which is filled with the refractive index adjusting material.  
     
     
         39 . The connecting method according to  claim 37 , wherein in said filling step the concave portion is filled with refractive index adjusting material comprising a resin adhesive.  
     
     
         40 . The connecting method according to  claim 37 , further comprising a step of hardening the refractive index adjusting material.  
     
     
         41 . A connecting structure for connecting optical fibers comprising: 
 a plastic optical fiber with a concave portion formed on its end face;    a second optical fiber; and    a refractive index adjusting material filled in the concave portion of the plastic optical fiber;    wherein end faces of said plastic optical fiber and said second optical fiber are opposed and bonded to each other to optically couple said plastic optical fiber and said second optical fiber to each other.    
     
     
         42 . The connecting structure according to  claim 41 , wherein said second optical fiber is also a plastic optical fiber with a concave portion formed on its end face, which is filled with the refractive index adjusting material.  
     
     
         43 . The connecting structure according to  claim 41 , wherein the refractive index adjusting material is a resin adhesive.  
     
     
         44 . The connecting structure according to  claim 41 , wherein the refractive index adjusting material is hardened.  
     
     
         45 . A connecting structure of a plastic optical fiber and a light-emitting/receiving device comprising: 
 a plastic optical fiber with a lens portion having a function of controlling light rays, said lens portion being formed of a refractive index adjusting material filled in a concave portion at an end face of said plastic optical fiber and having a refractive index different from a refractive index of said plastic optical fiber;    a light-emitting/receiving device; and    a substrate with a holding structure for holding said plastic optical fiber and an arranging portion for arranging said light-emitting/receiving device thereon;    wherein said plastic optical fiber is held in the holding structure to align said lens portion to said light-emitting/receiving device arranged on said arranging portion and optically couple said plastic optical fiber and said light-emitting/receiving device.    
     
     
         46 . The connecting structure according to  claim 45 , wherein the holding structure comprises a recess with a diameter larger than a diameter of said plastic optical fiber, said arranging portion comprises a bottom face of said recess, and a distance between said plastic optical fiber and said light-emitting/receiving device is adjusted by controlling an insertion depth of said plastic optical fiber into said recess.  
     
     
         47 . The connecting structure according to  claim 45 , wherein said holding structure comprises a stepped recess with an upper opening portion having a diameter slightly larger than a diameter of said plastic optical fiber and a lower opening portion having a diameter smaller than the diameter of said plastic optical fiber and a predetermined depth, said arranging portion comprises a bottom face of said stepped recess, and a distance between said plastic optical fiber and said light-emitting/receiving device is adjusted by causing the end face of said plastic optical fiber to abut a stepped face formed between said upper opening portion and said lower opening portion.  
     
     
         48 . The connecting structure according to  claim 45 , wherein said refractive index adjusting material is non-curable, and said non-curable refractive index adjusting material is filled in the surroundings of the light-emitting/receiving device.  
     
     
         49 . A method of optically connecting a plastic optical fiber to a light-emitting/receiving device comprising: 
 preparing a substrate with a holding structure for holding a plastic optical fiber with a lens portion formed at its end face and an arranging portion for arranging a light-emitting/receiving device thereon;    positioning the light-emitting/receiving device on the arranging portion; and    holding the plastic optical fiber in the holding structure so that the lens portion opposes the light-emitting/receiving device and optically couples the plastic optical fiber and the light-emitting/receiving device.    
     
     
         50 . The method of optically connecting a plastic optical fiber to a light-emitting/receiving device according to  claim 49 , wherein in said preparing step the holding structure is prepared so as to comprise a recess with a diameter slightly larger than a diameter of the plastic optical fiber, the arranging portion is prepared so as to comprise a bottom face of the recess, and a distance between the plastic optical fiber and the light-emitting/receiving device is adjusted by controlling an insertion depth of the plastic optical fiber into the recess.  
     
     
         51 . The method of optically connecting a plastic optical fiber to a light-emitting/receiving device according to  claim 49 , wherein in said preparing step the holding structure is prepared so as to comprise a stepped recess with an upper opening portion with a diameter slightly larger than a diameter of the plastic optical fiber and a lower opening portion with a diameter smaller than the diameter of the plastic optical fiber and a predetermined depth, the arranging portion is prepared so as to comprise a bottom face of the stepped recess, and a distance between the plastic optical fiber and the light-emitting/receiving device is adjusted by causing the end face of the plastic optical fiber to abut on a stepped face formed between the upper opening portion and the lower opening portion.  
     
     
         52 . The method of optically connecting a plastic optical fiber to a light-emitting/receiving device according to  claim 49 , further comprising steps of providing a non-curable refractive index adjusting material in a concave portion of the plastic optical fiber defining the lens portion, and then inserting the plastic optical fiber into the holding structure to fill the surroundings of the light-emitting/receiving device with the non-curable refractive index adjusting material.