Optical module

1. An optical module comprising:

first and second optical parts each having an optimum path extending in a longitudinal direction and an end face intersecting the optical path, wherein the end face of the first optical part faces the end face of the second optical part, and wherein light enters the end face of the second optical part from the end face of the first optical part;

an adhesive that forms a joint for connecting the faces of the parts to each other substantially only in peripheral portions about the optical paths of the parts; and

wherein the joint is reinforced with an adhesive that is different from the adhesive forming the joint.

2. The optical module according to claim 1 , wherein the adhesive is an ultraviolet curing adhesive or a visible light curing adhesive, and the viscosity of the adhesive is sufficiently high such that the adhesive does not penetrate toward the optical paths from the peripheral portion about the optical paths.

3. The optical module according to claim 1 , wherein an antireflection film is formed on each of the end faces of the first and second optical parts, and wherein the reflectivity of each antireflection film to a predetermined wavelength in a usable wavelength region is equal to or less than predetermined value.

4. The optical module according to claim 1 , wherein both of the first and second optical parts are lenses.

5. The optical module according to claim 1 , wherein the first optical part is a lens, and wherein the second optical lens is an optical fiber chip.

6. The optical module according to claim 1 , wherein the optical module is a three-port filter module, the filter module comprising:

first and second lenses;

a first optical fiber chip for holding two optical fibers, wherein the first optical fiber chip has an end face intersecting the optical fibers;

a second optical fiber chip for holding an optical fiber, wherein the second optical fiber chip has an end face intersecting the optical fiber; and

a filter coaxially provided between the first and second lenses,

wherein the end face of the first lens faces the end face of the first optical fiber chip, and peripheral portions of the end faces are fixed with the adhesive, and wherein the end face of the second lens faces the end face of the second optical fiber chip, and peripheral portions of the end faces are fixed with the adhesive.

7. A three-port module comprising:

A three-port module comprising:

first and second gradient index rod lenses;

a first optical fiber chip holding two optical fibers;

a second optical fiber chip holding an optical fiber; and

a Filter coaxially provided between the first and second rod lenses,

wherein the first and second rod lenses are adhered to each other to form a center piece; wherein the first and second rod lenses each have an endface that is perpendicular to an optical axis, the endfaces facing each other;

wherein the filter is formed on the end face of the first rod lens, and the end face of the second rod lens and the filter are fixed with the adhesive substantially only in peripheral portions about the optical axis located between the end faces of the first rod lens and the second rod lens; and

wherein the first and second rod lenses are fixed with reinforcing adhesive covering the adhesive.

8. The optical module according to claim 6 , wherein the first and second lenses are gradient index rod lenses each having two endfaces, wherein one of the two endfaces is perpendicular to an optical axis, and the other endface is inclined relative to the optical axis, and

wherein the endfaces of the two rod lenses face each other with the filter in between, and wherein the first and second lenses are fixed in a cylindrical lens holder while being coaxially aligned.

9. The optical module according to claim 8 , wherein the filter is formed on the endface of the first rod lens.

10. The optical module according to claim 7 , further comprising a housing for accommodating the optical module.

11. The optical module according to claim 10 , wherein the housing has a first through hole for guiding the two optical fibers of the first optical fiber chip from the housing to the outside, and a second through hole for guiding the optical fiber of the second optical fiber chip to the outside.

12. The optical module according to claim 11 , wherein the housing has first and second heat-shrinkable tubes for protecting the optical fibers guided to the outside through the first and second through holes.

13. The optical module according to claim 10 , wherein the housing is formed of an upper half and a lower half, which are formed by separating the housing along the optical axis of the optical module.

14. The optical module according to claim 13 , wherein the center piece is adhered to the lower half.

15. The optical module according to claim 12 , wherein the housing includes an upper half and a lower half which are formed by separating the housing along the optical axis of the optical module, and wherein the center piece is adhered to the lower half of the housing.

16. The optical module according to claim 12 , wherein the joint is reinforced with an adhesive that is different from the adhesive forming the joint.

17. The optical module according to claim 12 , wherein the adhesive is an ultraviolet or visible light curing adhesive.