Optical waveguide board and optical module

1. An optical waveguide board comprising:

a substrate;

an optical path changing unit being formed on said substrate used to change a direction of an optical path of incident light from a direction being vertical to a surface of said substrate to a direction being horizontal to said surface of said substrate and to condense a luminous flux;

an optical waveguide being formed on said substrate used to carry out multi-mode transmission of said luminous flux fed from said optical path changing unit; and

wherein, based on a spread angle of said luminous flux formed by said optical path changing unit, mainly light components to be transmitted in a zero-order mode to a three-order mode only, out of various kinds of modes for said multi-mode transmission, is transmitted through said optical waveguide.

2. The optical waveguide board according to claim 1 , wherein said optical path changing unit is constructed of an insulator having a surface of a spheroid and on said surface of said spheroid is formed a concave mirror made up of a metal film.

3. The optical waveguide board according to claim 1 or claim 2 , wherein an adhesive is filled between said optical path changing unit and said optical waveguide.

4. The optical waveguide board according to claim 3 , wherein said adhesive has almost a same refractive index as that of a core layer making up said optical waveguide.

5. The optical waveguide board according to claim 1 , wherein

said optical path changing unit is made up of an insulator and

on a surface of said insulator on a side of said optical waveguide is formed a plurality of spherical surfaces corresponding to a plurality of said optical waveguides being placed in parallel to one another.

6. The optical waveguide board according to claim 1 , wherein

said optical path changing unit is made up of an insulator and

on an upper surface of said insulator is formed a plurality of spherical surfaces corresponding to a plurality of said optical waveguides being placed in parallel to one another.

7. The optical waveguide board according to claim 1 , wherein

said optical path changing unit is made up of an insulator and

an upper surface of said insulator is arranged in a manner so as to be inclined relative to said substrate and wherein a spherical surface is formed on a light outgoing surface of said insulator.

8. The optical waveguide board according to claim 1 , wherein

said optical path changing unit is made up of an insulator and

on a side of said light source of said insulator is formed a first curved surface on which light is incident from said light source and on a side of said optical waveguide of said insulator is formed a second curved surface used to output light reflected on a plane mirror existing under a lower surface of said insulator, so that the output light enters into said optical waveguide.

9. An optical waveguide board comprising:

a multi-mode optical waveguide formed on a substrate used to receive and transmit light

wherein, when an angle of deviation of an optical path entering into said multi-mode optical waveguide is a spread half angle of light to be transmitted in a zero-order mode,

a luminous flux fed from said optical path is formed by a light condensing unit so as to have a spread half angle being about two times or more larger than said angle of deviation of said optical path and

said spread half angle of said luminous flux is set to be less than about 2.4 degrees.

10. An optical waveguide board comprising:

a plurality of light sources which emit a plurality of luminous fluxes in a first direction;

a light condensing unit; and

an optical waveguide, disposed within a surface of a substrate, comprising a plurality of optical waveguide components and defining an optical path;

wherein said optical waveguide further comprises an incident surface inclined with respect to said optical path defined by said optical waveguide; and

wherein the plurality of luminous fluxes emitted by said plurality of light sources

are incident on said incident on said light condensing unit,

are reflected and condensed by said light condensing unit,

are emitted from said light condensing unit in a second direction substantially perpendicular to said first direction, and

are incident on said incident surface of said optical waveguide.

11. The optical waveguide board according to claim 10 , wherein said light condensing unit comprises:

an insulator having an upper surface, a lower surface, and a convex surface; and

a mirror, disposed under said lower surface of said insulator;

wherein light incident on the upper surface

is refracted at said upper surface of said insulator and directed to said mirror,

is reflected off said mirror and redirected to said upper surface of said insulator,

is reflected at said upper surface of said insulator and directed to the convex surface, and

is condensed and transmitted through said convex surface of said insulator.

12. The optical waveguide board according to claim 10 , wherein said light condensing unit has a function of having a light beam in said optical path travel toward a direction of an optical axis of said optical waveguide.

13. An optical module comprising:

a light source and

an optical waveguide board comprising:

a substrate;

an optical path changing unit being formed on said substrate used to change a direction of an optical path of incident light from a direction being vertical to a surface of said substrate to a direction being horizontal to said surface of said substrate and to condense a luminous flux;

an optical waveguide being formed on said substrate to carry out multi-mode transmission of said luminous flux fed from said optical path changing unit; and

wherein, based on a spread angle of said luminous flux formed by said optical path changing unit, mainly light components to be transmitted in a zero-order mode to a three-order mode only, out of various kinds of modes for said multi-mode transmission, is transmitted through said optical waveguide.

14. An optical module comprising:

a light source made up of a surface light emitting device used to deflect a luminous flux in a specified direction, and

an optical waveguide board

wherein a multi-mode optical waveguide used to receive and transmit light fed from said light source is formed on a substrate and,

when an angle of deviation of an optical path entering into said optical waveguide is a spread half angle of light to be transmitted in a zero-order mode,

a luminous flux fed from said optical path is formed by a light condensing unit so as to have a spread half angle being about two times or more larger than said angle of deviation of said optical path and

said spread half angle of said luminous flux is set to be less than about 2.4 degrees and

wherein calibration is made by said light condensing unit so that an angular deviation in said optical path of a luminous flux entering into said optical waveguide relative to a direction in which light is transmitted in a zero-order mode in said optical waveguide is made smaller.

15. An optical module comprising:

a light source and

an optical waveguide board

wherein a multi-mode optical waveguide used to receive and transmit light fed from said light source is formed on a substrate and,

when an angle of deviation of an optical path entering into said optical waveguide is a spread half angle of light to be transmitted in a zero mode,

a luminous flux fed from said optical path is formed by a light condensing unit so as to have a spread half angle being about two times or more larger than said angle of deviation of said optical path and

said spread half angle of said luminous flux is set to be less than 2.4 degrees and

wherein

an optical path calibrating unit having a focusing distance being larger than that being used when an optical path is made smaller by said light condensing unit is placed between said light source and said light condensing unit and

said optical path calibrating unit is so configured as to be movable in parallel to a surface of said optical waveguide board and

wherein calibration is made by said light condensing unit so that an angular deviation in said optical path of a luminous flux entering into said optical waveguide relative to a direction in which light is transmitted in a zero-order mode in said optical waveguide is made smaller.

16. An optical module comprising:

a plurality of light sources;

an optical waveguide board on which the plurality of light sources is mounted;

an optical waveguide, disposed within a surface of a substrate, comprising a plurality of optical waveguide components and defining an optical path

a light condensing unit comprising an incident surface inclined with respect to said optical path defined by said optical waveguide;

wherein a plurality of luminous fluxes incident from said plurality of light sources in a first direction

are incident on said incident surface of said light condensing unit,

are reflected and condensed by said light condensing unit,

are emitted from said light condensing unit in a second direction substantially perpendicular to said first direction, and

are incident on the optical waveguide.