Manufacturing method of a polymer GRIN lens using sulfonation

• US 5,567,363 A
• Filed: 11/30/1994
• Issued: 10/22/1996
• Est. Priority Date: 10/14/1994
• Status: Expired due to Term

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: Song, Seok-Ho, Jung, Sang-Don
• Primary Examiner(s): Vargot, Mathieu D.
• Application Number:
  US08/352,044
• Time in Patent Office: 692 Days
• Field of Search: 264/1.36, 264/1.37, 264/1.38, 264/2.6, 264/1.1
• US Class Current: 264/2.6
• CPC Class Codes: B29D 11/00355 with a refractive index gradient
• CPC Class Codes: C08F 212/02 Monomers containing only one unsaturated aliphatic radical
• CPC Class Codes: C08F 8/36 Sulfonation; Sulfation
• CPC Class Codes: G02B 3/0087 with index gradient

Abstract

The present invention relates to a manufacturing method of a polymer GRIN lens which is used for focusing light in connections for example between two or more optical fibers and between an optical fiber and a light source in the optical communication field. The manufacturing method of a GRIN lens according to the present invention utilizes a characteristic of polystyrene that its refractive-index is decreased by sulfonation. The method includes polymerizing a sphere or rod made of a directional monomer that is capable of sulfonating like a styrene, together with a cross-linking agent, and a polymerization initiator; swelling the polymerized cross-linked polymer by using a predetermined solvent; and sulfonating the swollen cross-linked polymer using a sulfuric acid. Accordingly, the present method can be easily controlled to obtain the desired refractive-index distribution since the refractive-index distribution is determined by the diffusion of the sulfuric acid as a sulfonation.

Claims

1. Manufacturing method for making a sphere shaped polymer GRIN lens comprising the steps of:

forming a sphere shaped cross-linked polymer by suspension polymerization, after an aromatic monomer capable of sulfonating and having hydrophobicity is mixed with a polymerization initiator and cross-linked to form said cross-linked polymer;

swelling said cross-linked polymer by using a predetermined solvent; and

sulfonating said swelled cross-linked polymer so as to have the highest refractive-index distribution at a center portion of said sphere and a gradually decreasing refractive-index distribution outwardly from said center of said sphere by using a sulfuric acid which is heated at a predetermined temperature.

2. Manufacturing method of a rod shaped polymer GRIN lens comprising steps of:

forming a rod shaped cross-linked polymer by putting a mixture material into a tube and polymerizing it, said mixture material comprising an aromatic monomer capable of sulfonating and having hydrophobicity and hydrophilicity and a polymerization initiator;

swelling said cross-linked polymer by using a predetermined solvent, after said tube is removed; and

sulfonating said swelled cross-linked polymer so as to have the highest refractive-index distribution at a center portion of said rod and a gradually decreasing refractive-index distribution outwardly from said center of said rod by using a sulfuric acid which is heated at a predetermined temperature.

3. A method for making a polymer GRIN lens comprising the steps of:

providing an aromatic monomer capable of sulfonating and having hydrophobicity;

mixing a polymerization initiator with said monomer to form a polymerization suspension and to form a cross-linked polymer having a geometrical shape with a center portion and a surface in said suspension;

swelling said cross-linked polymer by using a predetermined solvent; and

sulfonating said swelled cross-linked polymer so as to have the highest refractive-index distribution at said center portion and a gradually decreasing refractive-index distribution outwardly from said center portion by using a sulfuric acid which is heated at a predetermined temperature.

4. A method for making a polymer GRIN lens as claimed in claim 3 wherein said geometrical shape is a sphere.

5. A method for making a polymer GRIN lens as claimed in claim 3 wherein said geometrical shape is a rod.

6. A method for making a polymer GRIN lens as claimed in claim 3 wherein said provided monomer is a directional monomer.

7. A method for making a polymer GRIN lens as claimed in claim 6 wherein said monomer is selected from the group consisting of styrene and naphthalene.

8. A method for making a polymer GRIN lens as claimed in claim 3 wherein said monomer is styrene.

9. A method for making a polymer GRIN lens as claimed in claim 8 wherein said sulfonating temperature is approximately 70 to 100 degrees.

10. A method for making a polymer GRIN lens as claimed in claim 3 wherein said sulfonating temperature is approximately 70 to 100 degrees.

11. A method for making a polymer GRIN lens as claimed in claim 3 wherein the surface of said cross-linked polymer is directly contacted with sulfuric acid so as to heavily sulfonate said surface.

12. A method for making a polymer GRIN lens as claimed in claim 3 wherein said polymerization initiator is a divinylbenzene.

13. A method for making a polymer GRIN lens as claimed in claim 12 wherein said provided monomer is a directional monomer and is selected from the group consisting of styrene and naphthalene;

wherein said sulfonating temperature is approximately 70 to 100 degrees; and

wherein the surface of said cross-linked polymer is directly contacted with sulfuric acid so as to heavily sulfonate said surface.