JP2007094213A - Optical transmitting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical transmitting system for stably transmitting data regardless of a relative position of an optical fiber and a light receiving element even when the optical fiber has a fluctuating curved state and a short optical path length. <P>SOLUTION: The optical transmitting system couples the light to the optical fiber by previously uniforming a far field pattern of light from a light emitting element. The optical transmitting system comprises the light emitting element and a pipe type waveguide in which a cross section shape is polygonal in a direction normal to the propagation direction of light of an optical waveguide region propagating light from the light emitting element incident on an incident end to an emission end by mirror face reflection or the total reflection. The pipe type waveguide guides light to the emission end by mirror-face-reflecting or totally reflecting light from the light emitting element coupled to the incident end by a reflection face surrounding the optical waveguide region. ("Vertical cross section shape in a propagation direction of light" is hereafter abbreviated to "cross section shape".) When the cross section shape is circular, light from the light emitting element tends to generate a stationary wave (mode) passing the center of a circle by being mirror-face reflected or totally reflected by light from the light emitting element, and the FFP tends to have lange intensity in the vicinity of the center. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical transmission apparatus that performs optical data transmission between modules.

  In recent years, as mobile phones that have become widespread, folding type, slide type, and rotary type mobile phones have come to be frequently used for convenience and other reasons during use and carrying. In the case of a foldable, slide-type, or rotary-type mobile phone, modules such as a communication function unit, an amplifier circuit unit, and a display circuit unit are distributed and arranged in a plurality of cases. Wiring connecting the arranged modules is required to be flexible and strong enough to withstand driving.

  In addition, wiring between each module requires high-speed data transmission due to the multi-functionality of mobile phones such as music playback function, video playback function, and photography function, countermeasures against electromagnetic interference with external devices, and demands for long-term use. Therefore, low power consumption is required.

An attempt has been made to use an optical fiber as a wiring that satisfies these requirements (for example, see Patent Document 1). In the following description, a module that performs optical data transmission by connecting each module with an optical fiber is referred to as an optical communication module.
JP2003-244295A.

  When an optical fiber is used for wiring between modules, the module is equipped with a light emitting element that enters light into the optical fiber and a light receiving element that receives light emitted from the optical fiber, and the light receiving element emits light that propagates through the optical fiber. Data transmission is performed by receiving light from the element. Further, in order to perform smooth data transmission, it is necessary to align the optical axes between the light emitting element and the optical fiber and between the optical fiber and the light receiving element. In the following description, “arrange the optical axes” is abbreviated as “alignment”.

In order to facilitate alignment, it is desirable to increase the diameter of the optical fiber core. However, if the optical fiber core diameter is large, the center axis of the optical fiber is Light may enter from different positions.
When the optical path length of the optical fiber is long, even if light is incident from a position different from the central axis of the optical fiber, the light is disturbed during propagation through the optical fiber. “Near field pattern” is abbreviated as “NFP”).

  However, in the case of an optical fiber that is as short as several centimeters as between mobile phone modules and has a sharp bend with a curvature radius of about 5 mm, if light enters from a position different from the central axis of the optical fiber, Since the light is not sufficiently disturbed during propagation, the NFP at the other end of the optical fiber is non-uniform.

  On the other hand, the diameter of the light receiving surface of the light receiving element is required to be small in order to perform high-speed data communication. When the diameter of the light receiving surface of the light receiving element is small, the light receiving element cannot receive all of the light emitted from the other end of the optical fiber, and can only receive light from a part of the other end of the optical fiber. become.

  Therefore, when the core diameter of the optical fiber is large and the diameter of the light receiving surface of the light receiving element is small, the light receiving element cannot receive a sufficient amount of light due to the non-uniform NFP depending on the relative position between the optical fiber and the light receiving element. Sometimes.

Further, since the bending state of the optical fiber varies depending on the operation such as folding and rotation of the mobile phone, the NFP also varies depending on the bending state.
Therefore, even if the assembly accuracy of the optical fiber and the light receiving element is improved and alignment is performed according to the NFP, the light receiving element may not receive a sufficient amount of light and may not be able to transmit data stably.

  The present invention has been made to solve the above-described problems, and even with an optical fiber having a short optical path length and a variable bending state, stable data transmission can be performed regardless of the relative position between the optical fiber and the light receiving element. An object is to provide an optical transmitter.

  In order to achieve the above object, an optical transmission apparatus according to the present invention makes a far field pattern of light from a light emitting element (hereinafter, “far field pattern” abbreviated as “FFP”) uniform in advance. It was decided to combine with.

  Specifically, the present invention relates to a light emitting element and a shape of a cross section perpendicular to the light propagation direction of an optical waveguide region that propagates light from the light emitting element incident on the incident end to the exit end by specular reflection or total reflection. Is a polygonal tube-shaped waveguide.

  The tubular waveguide guides light from the light emitting element coupled to the incident end with a reflecting surface surrounding the optical waveguide region to the exit end by specular reflection or total reflection. When the shape of the cross section perpendicular to the light propagation direction in the optical waveguide region of the tubular waveguide (hereinafter, “the shape of the cross section perpendicular to the light propagation direction” is abbreviated as “cross section shape”) is described above. Light from the light-emitting element is likely to be specularly reflected or totally reflected to generate a standing wave (mode) that passes through the center of the circle, and tends to be FFP with strong light intensity near the center.

  On the other hand, the cross-sectional shape of the optical waveguide region of the tubular waveguide in the optical transmission device according to the present invention is a polygon, and the light path is complicated, so that the guided light is disturbed for each specular reflection or total reflection. Therefore, the tubular waveguide can make the FFP of the light from the light emitting element uniform even if the optical path length is short (hereinafter, “the tubular waveguide in which the cross-sectional shape of the optical waveguide region is a polygon). "Is abbreviated as" polygonal tube waveguide "). Therefore, the optical transmitter can emit light having a uniform light intensity distribution at the exit end of the polygonal tube waveguide.

  If the emitting end and one end of the optical fiber are connected, the optical transmitter uniformly distributes the light intensity distribution in advance in the optical coupling range that is the size of the optical waveguide region at the emitting end in the plane of one end of the optical fiber. The combined light can be combined.

  Therefore, even if the optical path length of the optical fiber is short, the optical transmission device can make the NFP uniform at the other end of the optical fiber. Further, even if the optical fiber is bent, the optical transmission device can alleviate the NFP bias at the other end of the optical fiber. Therefore, the light receiving element connected to the other end of the optical fiber can receive a sufficient amount of light even if the light receiving surface is small.

  Therefore, the present invention can provide an optical transmitter capable of stably transmitting data regardless of the relative position between the optical fiber and the light receiving element, even if the optical path length is short and the bending state is changed. .

  In the present invention, the shape of a cross section perpendicular to the light propagation direction of a light-emitting element and an optical waveguide region that propagates light from the light-emitting element incident on the incident end to the output end by specular reflection or total reflection is a rounded polygon. And a tube-type waveguide.

  A rounded polygon is a shape obtained by rounding at least one of vertices of a polygon. In the optical transmission device, since the cross-sectional shape of the optical waveguide region of the tubular waveguide is a rounded polygon, the same effect as that of the optical transmission device including the polygonal tubular waveguide can be obtained.

  Therefore, the present invention can provide an optical transmitter capable of stably transmitting data regardless of the relative position between the optical fiber and the light receiving element, even if the optical path length is short and the bending state is changed. .

  According to the present invention, the shape of the cross section perpendicular to the light propagation direction of the light emitting element and the light guiding region in which light from the light emitting element incident on the incident end propagates to the emission end by specular reflection or total reflection has a plurality of curvatures. And a tubular waveguide having a shape surrounded by a single closed curve.

  The cross-sectional shape of the tube-type waveguide of the optical transmitter is a shape surrounded by a single closed curve having a plurality of curvatures (hereinafter referred to as “a shape surrounded by a single closed curve having a plurality of curvatures”). Is abbreviated as “single closed curve shape”), the same effects as those of the optical transmission device including the polygonal tube waveguide can be obtained.

  Therefore, the present invention can provide an optical transmitter capable of stably transmitting data regardless of the relative position between the optical fiber and the light receiving element, even if the optical path length is short and the bending state is changed. .

  In the present invention, the shape of a cross section perpendicular to the light propagation direction of a light emitting element and an optical waveguide region that propagates light from the light emitting element incident on the incident end to the exit end by specular reflection or total reflection has a plurality of curves. An optical transmission device comprising: a tubular waveguide having a shape surrounded by connecting ends and a shape having a singular point at a connection point of the plurality of curves.

  The cross-sectional shape of the tube-type waveguide of the optical transmission device is a shape surrounded by connecting ends of a plurality of curves and a shape having a singular point at a connection point of the plurality of curves (hereinafter, “a plurality of curves”). For example, a shape surrounded by connecting ends of each other and a shape having a singular point at a connection point of the plurality of curves is abbreviated as “a plurality of curve shapes”). The same effect as that of the optical transmitter can be obtained.

  Therefore, the present invention can provide an optical transmitter capable of stably transmitting data regardless of the relative position between the optical fiber and the light receiving element, even if the optical path length is short and the bending state is changed. .

  The present invention relates to a light emitting element and a line having at least one line in a shape perpendicular to the light propagation direction of an optical waveguide region in which light from the light emitting element incident on the incident end propagates to the exit end by specular reflection or total reflection. An optical transmission device comprising: a tubular waveguide having a shape surrounded by connecting an end of a minute and an end of at least one curve.

  The cross-sectional shape of the tubular waveguide of the optical transmission device is a shape surrounded by connecting at least one line segment end and at least one curve end (hereinafter referred to as “at least one line segment end”). The shape surrounded by connecting at least one end of the curve is abbreviated as “line segment curve shape”). Therefore, the same effect as that of the optical transmission device including the polygonal tube waveguide is obtained. be able to.

  Therefore, the present invention can provide an optical transmitter capable of stably transmitting data regardless of the relative position between the optical fiber and the light receiving element, even if the optical path length is short and the bending state is changed. .

  The optical transmission device according to the present invention further includes a multimode optical fiber having one end connected to the emission end of the tube-type waveguide, and light from the tube-type waveguide entering the core, and the tube-type The optical waveguide region on the exit end face of the waveguide has a size contained in the cross section of the core on the one end face of the optical fiber.

  The optical transmission device connects a multimode type optical fiber to the emission end of the tubular waveguide. The cross-sectional size perpendicular to the light propagation direction of the core of the optical fiber is larger than the cross-sectional size perpendicular to the light propagation direction of the optical waveguide region at the emission end.

  As a result of providing the optical fiber, the tube-type waveguide can couple light having a uniform light intensity distribution in advance to the optical coupling range at one end of the optical fiber. Therefore, even if the optical path length of the optical fiber is short, the optical transmitter can make the NFP at the other end of the optical fiber uniform and emit light with a uniform light intensity distribution. Further, even if the optical fiber is bent, the optical transmission device can emit light in which the NFP bias at the other end of the optical fiber is reduced. Therefore, the light receiving element connected to the other end of the optical fiber of the optical transmitter can receive a sufficient amount of light even if the light receiving surface is small.

  Therefore, the present invention can provide an optical transmitter capable of stably transmitting data regardless of the relative position between the optical fiber and the light receiving element, even if the optical path length is short and the bending state is changed. .

In the optical transmission device according to the present invention, it is preferable that an area of a cross section perpendicular to the light propagation direction of the optical waveguide region of the tubular waveguide monotonously decreases from the incident end to the emission end.
The tube-type waveguide of the optical transmitter has the same effect as that of the polygonal tube-type waveguide.

  Furthermore, since the shape of the tubular waveguide is such that the area of the cross section perpendicular to the light propagation direction of the optical waveguide region decreases from the incident end to the exit end, the tube waveguide extends from the exit end to the exit end. The light can be concentrated. Therefore, the light intensity at the emission end becomes strong, and the optical transmitter can further alleviate the bias of NFP at the other end of the optical fiber due to bending.

  In the following description, “a tubular waveguide in which the area of the cross section perpendicular to the light propagation direction in the optical waveguide region monotonously decreases from the incident end to the exit end” is abbreviated as “tapered waveguide”.

  Therefore, the present invention can provide an optical transmitter capable of stably transmitting data regardless of the relative position between the optical fiber and the light receiving element, even if the optical path length is short and the bending state is changed. .

  In the optical transmission device according to the present invention, the rate of decrease of the area of the optical waveguide region of the tubular waveguide in the cross section perpendicular to the optical propagation direction with respect to the distance in the optical propagation direction is from the incident end toward the output end. It is preferable to be smaller.

  In the tapered waveguide, since the incident angle with respect to the reflecting surface of the light from the light emitting element is reduced every time the mirror is reflected or totally reflected, the light that has been specularly reflected or totally reflected more than a certain number of times is included in the incident end. Will return to the side. By reducing the taper shape of the optical waveguide region from the incidence end toward the output end, the reflection surface of the optical waveguide region approaches the light propagation direction on the emission end side. Since the tapered tubular waveguide can maintain the incident angle of light incident on the reflecting surface at a certain value or more, the light that has undergone specular reflection or total reflection more than a certain number of times on the reflecting surface returns to the light emitting element side. This can be prevented, and transmission loss of light from the light emitting element can be reduced. Further, when the tapered waveguide propagates by totally reflecting light, the same effect can be obtained by keeping the incident angle of light at a certain value or more and below the angle at which total reflection is possible.

  Further, the tapered waveguide can maintain the incident angle of light coupled to the optical fiber at a predetermined value or more at the boundary surface between the core and the clad of the optical fiber, and can reduce the amount of light transmitted to the clad. Can be reduced. Therefore, the tapered waveguide can reduce transmission loss in the optical fiber.

  Therefore, the present invention provides an optical transmission device that can stably transmit data regardless of the relative position between the optical fiber and the light receiving element, and has a small transmission loss, even with an optical fiber having a short optical path length and a bent state. Can be provided.

  In the optical transmission device according to the present invention, the area of the cross section perpendicular to the light propagation direction of the optical waveguide region of the tubular waveguide may monotonously increase from the incident end toward the emission end.

  The shape of the optical waveguide region of the tube-shaped waveguide is a shape in which the area of a cross section perpendicular to the light propagation direction of the optical waveguide region extends from the incident end toward the output end, so that the emission end The FFP of the light emitted from can be expanded. Therefore, light having a uniform light intensity distribution in advance can be coupled to a wide optical coupling range at one end of an optical fiber having a large diameter. Therefore, the optical transmission device can obtain the same effect as that of the optical transmission device including the polygonal tube waveguide.

  In the following description, “a tube waveguide whose cross-sectional area perpendicular to the light propagation direction in the optical waveguide region monotonously increases from the incident end to the exit end” is abbreviated as “reverse tapered waveguide”.

  Therefore, the present invention provides an optical transmission device that can stably transmit data regardless of the relative position between the optical fiber and the light receiving element, even with an optical fiber having a short optical path length and a bent state. it can.

  In the optical transmission device according to the present invention, the shape of the cross section perpendicular to the light propagation direction of the optical waveguide region in one section of the tube-type waveguide and the light of the optical waveguide region in the other section of the tube-type waveguide. The cross-sectional shape perpendicular to the propagation direction may be different.

  Since the standing wave is converted by propagation of light from one section to another section, the tube-type waveguide is disturbed in the propagation mode, and uniforms the FFP of the light from the light emitting element.

  If the light from the tube-type waveguide is coupled to the optical coupling range at one end of the optical fiber, the optical transmission device obtains the same effect as described for the polygonal tube-type waveguide at the other end of the optical fiber. be able to.

  Therefore, the present invention can provide an optical transmitter capable of stably transmitting data regardless of the relative position between the optical fiber and the light receiving element, even if the optical path length is short and the bending state is changed. .

  The present invention can provide an optical transmitter capable of stably transmitting data regardless of the relative position between the optical fiber and the light receiving element, even if the optical path length is short and the bending state is changed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to embodiment shown below.

(Embodiment 1)
One embodiment according to the present invention is a light emitting element and a shape of a cross section perpendicular to the light propagation direction of an optical waveguide region in which light from the light emitting element incident on the incident end propagates to the exit end by specular reflection or total reflection. Is a polygonal tube-shaped waveguide.

  FIG. 1 shows a conceptual diagram of an optical transmission apparatus 101 according to an embodiment of the present invention. The optical transmission device 101 includes a light emitting element 11 and a tube waveguide 14. FIG. 1 is a sectional view taken along a plane including the central axis of the tubular waveguide 14. In addition, what can be realized by a normal technique such as a power source, a peripheral circuit, and a substrate necessary for the light emitting element 11 is not illustrated in FIGS. 1 and 22 and subsequent drawings.

  The light emitting element 11 converts an electrical signal into signal light A and radiates the signal light A from the surface to the outside. An LED or a surface emitting LD can be used as the light emitting element 11. A VCSEL can be exemplified as the surface emitting LD.

  The tube-type waveguide 14 is a hollow tube whose one end is an incident end 15 where light enters and the other end is an output end 16 where light is emitted. The inner wall of the tube is surrounded by the reflecting surface 18 of the reflecting mirror, and the light repeats specular reflection at the reflecting surface 18. A portion surrounded by the reflection surface 18 is an optical waveguide region 19, and the light is confined in the optical waveguide region 19 and propagates from the incident end 15 to the output end 16. The cross-sectional shape of the optical waveguide region 19 is a polygon. Examples of the cross-sectional shape at T-T ′ of the optical waveguide region 19 are shown in FIGS. 2 to 7 and 21. The unit is mm. FIG. 2 is a triangle, FIG. 3 is a regular triangle, FIG. 4 is a square, FIG. 5 is a regular pentagon, FIG. 6 is a regular hexagon, FIG. 7 is a regular icosahedron, and FIG.

  The tube waveguide 14 may have a structure in which a medium having a high refractive index is covered with a medium having a low refractive index. Since the light is totally reflected at the interface between the two media, the interface can be used as the reflection surface 18.

  Accordingly, since the cross-sectional shape of the optical waveguide region 19 is polygonal, the light is disturbed by repeating specular reflection or total reflection at the reflection surface 18, and the tubular waveguide 14 has a short optical path length and an incident end at the output end 16. The FFP of light from 15 is made uniform.

  The optical transmission device 101 aligns and connects the light emitting element 11 to the incident end 15 of the tubular waveguide 14.

  The optical transmission apparatus 101 operates as described below. Data to be transmitted is converted into an electric signal in a format that can be transmitted by a peripheral circuit (not shown) and transmitted to the light emitting element 11. The light emitting element 11 converts the electric signal and emits signal light A. The signal light A radiated from the light emitting element 11 is coupled to the tubular waveguide 14. Since the tubular waveguide 14 is the polygonal tubular waveguide, the optical transmitter 101 can uniformize the FFP of the signal light A of the light emitting element 11 and emit the outgoing light B having a uniform light intensity distribution from the outgoing end 16. .

  Therefore, the optical transmission apparatus 101 can stably transmit data regardless of the relative position between the optical fiber and the light receiving element even if the optical fiber to be connected has a short optical path length and the bent state fluctuates.

  Note that the size of the optical waveguide region 19 on the surface of the incident end 15 is set in consideration of an assembly error when connecting the light emitting element 11 and the tubular waveguide 14. FIG. 22 shows the relative position relationship between the incident end 15 of the tubular waveguide 14 and the light emitting surface 11a of the light emitting element 11 when there is an assembly error. 22, the same reference numerals as those used in FIG. 1 have the same functions and the same arrangement. In FIG. 22, 14a indicates the center point of the tubular waveguide 14, and 22 indicates assembly accuracy. In FIG. 22, a region 26 in which the center of the light emitting surface 11 a of the light emitting element 11 aligned with the assembly accuracy 22 may be arranged is indicated by a region 26.

  For example, when the light emitting surface 11a of the light emitting element 11 is a circle having a diameter of 0.02 mm and the shape of the optical waveguide region 19 on the surface of the incident end 15 is a square having a side of 0.127 mm, the light emitting element 11 and the tubular waveguide 14 Even if there is an error of ± 0.05 mm in assembly, the light emitting element 11 can couple the signal light A to the tubular waveguide 14.

  Therefore, the optical transmission device 101 can reduce the alignment accuracy between the light emitting element 11 and the tubular waveguide 14.

  The cross-sectional shape of the optical waveguide region 19 may be a rounded polygon, a single closed curve, a multiple curve, or a line segment curve. Examples of the cross-sectional shape at TT ′ of the optical waveguide region 19 are shown in FIG. 12 in the case of a rounded polygon, in FIGS. 13 to 16 in the case of a multicurve shape, and in FIG. 8 in the case of a line segment curve shape. It is shown in FIGS. 11 and 17 to 20. The unit is mm.

  Even when the cross-sectional shape of the optical waveguide region 19 is a rounded polygon, a single closed curve shape, a multiple curve shape, or a line segment curve shape, the same effect as in the case of the polygonal tube waveguide is obtained. Can uniformize the FFP of the signal light A of the light emitting element 11 with a short optical path length, and emit the outgoing light B having a uniform light intensity distribution from the outgoing end 16.

  The rounded octagon in FIG. 12 is a shape in which each vertex of a square is rounded so as to be an arc having a diameter of 0.24 mm centering on the intersection of the square diagonal lines. Since the cross-sectional shape of the core of the optical fiber is circular, the tubular waveguide whose cross-sectional shape is a rounded polygon can relax the alignment accuracy required between the optical fiber and the light guide. Further, by rounding the vertices of the polygon, deformation of the apex portion can be prevented and the cross-sectional shape can be protected.

(Embodiment 2)
In the optical transmission device according to the present invention, the shape of the cross section perpendicular to the light propagation direction of the optical waveguide region in one section of the tube-type waveguide and the light of the optical waveguide region in the other section of the tube-type waveguide. The cross-sectional shape perpendicular to the propagation direction may be different.

  FIG. 23 shows a conceptual diagram of an optical transmission apparatus 103 which is another embodiment according to the present invention. The optical transmission device 103 includes a light emitting element 11 and a tubular waveguide 34. FIG. 23 is a cross-sectional view taken along a plane including the central axis of the tubular waveguide 34. 23, the same reference numerals as those used in FIG. 1 have the same functions and the same arrangement. The difference between the optical transmission device 101 and the optical transmission device 103 in FIG. 1 is that the tube-type waveguide 14 is provided instead of the tube-type waveguide 14.

  The tube-type waveguide 24 is composed of a tube-type waveguide 34a and a tube-type waveguide 34b whose optical waveguide regions 19 have different cross-sectional shapes. For example, when the cross-sectional shape of the optical waveguide region 19 at SS ′ of the tubular waveguide 34a is the shape of FIG. 2, the cross-sectional shape of the optical waveguide region 19 at UU ′ of the tubular waveguide 34b is from FIG. It can be set as the shape of FIG.

  The tube-type waveguide 34 a and the tube-type waveguide 34 b guide the light incident from the incident end 15 to the output end 16 in the same manner as the tube-shaped waveguide 14 of FIG.

  Since propagation of light from the tube waveguide 34a to the tube waveguide 34b converts standing waves, the propagation mode can be disturbed, and the tube waveguide 34 is shorter than the tube waveguide 14 of FIG. The FFP of the signal light A of the light emitting element 11 can be made uniform by the optical path length.

  Therefore, the optical transmission device 103 can obtain the same effect as that of the optical transmission device 101 of FIG.

  Further, in the optical transmission device 103, the cross-sectional shape of the light transmission region 19 of the tubular waveguide 34b is preferably a circle. Specifically, a tube-shaped waveguide 34 is configured by connecting a tube-shaped waveguide 34 a whose cross-sectional shape of the light transmission region 19 is a square and a tube-shaped waveguide 34 b whose cross-sectional shape of the light-transmission region 19 is a circle. be able to. When the output end 16 and the optical fiber are connected, since the cross-sectional shape of the core of the optical fiber is circular, the alignment accuracy required between the tubular waveguide 34 and the optical fiber can be relaxed.

(Embodiment 3)
The optical transmission device according to the present invention further includes a multimode optical fiber having one end connected to the emission end of the tube-type waveguide, and light from the tube-type waveguide entering the core, and the tube-type The optical waveguide region on the exit end face of the waveguide has a size contained in the cross section of the core on the one end face of the optical fiber.

  FIG. 24 shows a conceptual diagram of an optical transmission apparatus 104 according to another embodiment of the present invention. The optical transmission device 104 includes a light emitting element 11, a tube waveguide 14, and an optical fiber 45. 24, the same reference numerals as those used in FIG. 1 have the same functions and the same arrangement. In FIG. 24, the cross-sectional shape of the light transmission region 19 of the tubular waveguide 24 is assumed to be a square.

  The optical fiber 45 is a multimode type optical fiber composed of a core 45a and a clad 45b. The optical fiber 45 may be a glass fiber, a plastic fiber (POF), or an optical fiber having a glass core and a plastic cladding. It can be exemplified that the length of the optical fiber is 5 mm or more and 300 mm or less. One end of the optical fiber 45 is an incident end 46 that receives light, and the other end is an output end 47 that emits light. 24, 26, 27, and 28, the emission end 47 is not shown.

  The optical transmission device 104 connects the emission end 16 of the tubular waveguide 14 and the incident end 46 of the optical fiber 45. Since the tube-type waveguide 14 emits the outgoing light B from the outgoing end 16 as described in FIG. 1, the outgoing light B whose light intensity distribution has become uniform in advance in the optical coupling range of the incident end 46 of the optical fiber 45 is generated. Can be combined.

Therefore, the optical transmission device 104 can stably transmit data regardless of the relative position between the optical fiber and the light receiving element, even if the optical fiber has a short optical path length and a bent state.
The size of the optical waveguide region 19 on the surface of the emission end 16 is set in consideration of the assembly accuracy when the optical fiber 45 and the tubular waveguide 14 are connected. FIG. 25 shows the relationship between the relative positions of the incident end 46 of the optical fiber 45 and the exit end 16 of the tubular waveguide 14. In FIG. 25, the same reference numerals as those used in FIGS. 1, 22 and 24 have the same functions and the same arrangement. 45 c is the central axis of the optical fiber 45. Reference numeral 52 denotes an assembly accuracy, and an area 56 in which the central axis 12 of the tubular waveguide 14 aligned with the assembly accuracy 52 may be disposed is indicated by an area 56.

  For example, when the cross-sectional shape of the core 45a of the optical fiber 45 is a circle having a diameter of 0.24 mm and the shape of the optical waveguide region 19 on the surface of the emission end 16 is a square having a diagonal of 0.14 mm, the optical fiber 45 and the tubular waveguide 14 are used. Even if there is an error of ± 0.05 mm in the assembly, the tubular waveguide 14 can couple the outgoing light B to the optical fiber 45.

  Therefore, the optical transmission device 104 can reduce the alignment accuracy between the optical fiber 45 and the tubular waveguide 14.

(Embodiment 4)
In the optical transmission device according to the present invention, it is preferable that an area of a cross section perpendicular to the light propagation direction of the optical waveguide region of the tubular waveguide monotonously decreases from the incident end toward the emission end.

  FIG. 26 shows a conceptual diagram of an optical transmission apparatus 106 which is another embodiment according to the present invention. The optical transmission device 106 includes a light emitting element 11, a tapered waveguide 64 serving as the tubular waveguide, and an optical fiber 45. FIG. 26 is a sectional view taken along a plane including the central axis 62 of the tapered waveguide 64 and the central axis 45 c of the optical fiber 45. 26, the same reference numerals as those used in FIGS. 1 and 24 have the same functions and the same arrangement. In FIG. 26, the cross-sectional shape of the optical transmission region 19 of the tapered waveguide 64 is described as a square.

  The tapered waveguide 64 has the same configuration as the tubular waveguide 14 and has the same function. The difference between the tapered waveguide 64 and the tube waveguide 14 is that the area of the cross-sectional shape of the optical transmission region 19 is monotonously decreased from the incident end 15 to the exit end 16.

  The optical transmitter 106 connects the tapered waveguide 64 and the optical fiber 45 so that the central axis 62 and the central axis 45c are parallel to each other.

  The reduction rate of the area of the cross-sectional shape of the optical transmission region 19 with respect to the distance of the central axis 62 can be expressed by a taper angle β. The taper angle β is an angle formed by two tangents on the cut surface of the reflective surface 18 at the intersection of the intersecting line of the cut surface and the reflective surface 18 and the cross section where the tapered waveguide 64 is provided. The taper angle β of the tapered waveguide 64 is the same value from the entrance end 15 to the exit end 16.

  The taper angle β of the tapered waveguide 64 can be designed so that the amount of transmitted light that passes through the clad 45b at the boundary surface between the core 45a and the clad 45b of the optical fiber 45 is 30% or less of the incident light amount. preferable.

  Further, the taper angle β of the tapered waveguide 64 is more preferably designed so that the light E is totally reflected at the boundary surface of the optical fiber 45. The range of the taper angle β totally reflected at the boundary surface will be described below.

The refractive index of the optical transmission region 19 is n ₁ , the refractive index of the core 45 a of the optical fiber 45 is n ₂ , the refractive index of the clad 45 b of the optical fiber 45 is n ₃ , and the refractive index outside the optical transmitter 106 is n ₀ . To do. In FIG. 26, a parallel line 61 is a virtual line parallel to both the center line 62 and the center line 45c.

In FIG. 26, it is assumed that the signal light A emitted from the light emitting element 11 is emitted at the maximum angle with respect to the central axis 62. The angle formed by the light E with the central axis 62 is the light emission angle α, and the light E repeats specular reflection or total reflection at the reflecting surface 18, and the angle formed with the center line 62 immediately before being emitted from the emission end 16 is the emission angle θ _1. The angle formed by the parallel line 61 before the light E exits from the exit end 16 and enters the entrance end 46 of the optical fiber 45 is the incident angle θ ₀ , and the light E enters the core 45a and the core 45a and the clad 45b. The angle of incidence incident on the boundary surface is defined as the angle of incidence θ ₂ .

Since the reflecting surface 18 has a taper angle β, the light E is repeatedly specularly reflected or totally reflected by the reflecting surface 18 so that the angle formed between the traveling direction of the light E and the central axis 62 is large for each specular reflection or total reflection. Become. Therefore, there is a relationship of Formula 1 between the light emission angle α and the emission angle θ ₁ .

入射の角度θ_２は光Ｅがコア４５ａとクラッド４５ｂとの境界面で全反射をするためには前記境界面における臨界角θ_ｃ以下、すなわち数２を満たす必要がある。

The incident angle θ ₂ needs to satisfy the critical angle θ _c or less at the boundary surface, that is, Equation _{2 in order} for the light E to be totally reflected at the boundary surface between the core 45a and the clad 45b.

また、入射の角度θ_２と入射の角度θ_０とは数３の関係がある。

Further, the incident angle θ ₂ and the incident angle θ ₀ have a relationship of Equation 3.

さらに、出射の角度θ_１と入射の角度θ_０とは数４の関係がある。

Furthermore, the angle of emergence θ ₁ and the angle of incidence θ ₀ have a relationship of Equation 4.

また、光Ｅがテーパー型導波路６４内で入射端１５から出射端１６に至るまでに鏡面反射又は全反射する回数をｋとすると、出射の角度θ_１、ｋ、光放射角度α及びテーパー角βの間に数５の関係がある。

Further, when the number of times that the light E is specularly reflected or totally reflected from the incident end 15 to the exit end 16 in the tapered waveguide 64 is k, the exit angle θ ₁ , k, the light emission angle α, and the taper angle. There is a relationship of Equation 5 between β.

従って、光Ｅが光ファイバ４５の前記境界面で全反射するためにはテーパー角βは数６より小さい値に設計することが望ましい。

Therefore, in order for the light E to be totally reflected at the boundary surface of the optical fiber 45, it is desirable to design the taper angle β to a value smaller than Equation 6.

  The tapered waveguide 64 can be coupled to the optical coupling range of the incident end 46 of the optical fiber 45 by applying the signal light A from the light emitting element 11 to the emission end 16 to make the FFP uniform and concentrated.

  Therefore, the optical transmission device 106 can stably transmit data regardless of the relative position between the optical fiber and the light receiving element, even if the optical fiber has a short optical path length and a bent state.

(Embodiment 5)
In the optical transmission device according to the present invention, the rate of decrease of the area of the optical waveguide region of the tubular waveguide in the cross section perpendicular to the optical propagation direction with respect to the distance in the optical propagation direction is from the incident end toward the output end. It is preferable to be smaller.

  FIG. 27 shows a conceptual diagram of an optical transmission apparatus 107 which is another embodiment according to the present invention. The optical transmission device 107 includes a light emitting element 11, a tapered waveguide 74 as an optical waveguide, and an optical fiber 45. FIG. 27 is a cross-sectional view taken along a plane including the central axis 72 of the tapered waveguide 74 and the central axis 45 c of the optical fiber 45. In FIG. 27, the same reference numerals as those used in FIGS. 1, 24 and 26 have the same functions and the same arrangement. In FIG. 27, description will be made assuming that the cross-sectional shape of the light transmission region 19 of the tubular waveguide 74 is a square.

  The tubular waveguide 74 has the same configuration as the tapered waveguide 64 and has the same function. The difference between the tube-type waveguide 74 and the tapered waveguide 64 is that the rate of decrease in which the cross-sectional shape of the optical transmission region 19 monotonously decreases from the incident end 15 toward the exit end 16 toward the exit end 16 from the entrance end 15. It is getting smaller.

Since the angle theta ₁ of the light E emitted is related to the number 5, the angle theta ₁ to the extent taper angle β is greater or specular reflection or emission as the number of times k in the total reflection increases. Therefore, if the taper angle β exceeds a certain value or the number of specular reflections or total reflections k exceeds a certain value, the emission angle θ ₁ exceeds 90 degrees, so that the light E returns to the incident end 15.

The tubular waveguide 74 has a taper angle β that decreases from the incident end 15 to the output end 16, so that even if the taper angle β is large in the vicinity of the incident end 15 and the number of mirror reflections or total reflections k is large, Since the angle θ ₁ does not exceed 90 degrees, the light E does not return to the incident end 15.

  Therefore, the optical transmission device 107 can stably transmit data regardless of the relative position between the optical fiber and the light receiving element, even if the optical fiber has a short optical path length and a bent state.

(Embodiment 6)
In the optical transmission device according to the present invention, it is preferable that an area of a cross section perpendicular to the light propagation direction of the optical waveguide region of the tubular waveguide monotonously increases from the incident end toward the emission end.

  FIG. 28 shows a conceptual diagram of an optical transmission apparatus 108 according to another embodiment of the present invention. The optical transmission device 108 includes a light emitting element 11, an inverted tapered waveguide 84 as the tube waveguide, and an optical fiber 45. FIG. 28 is a cross-sectional view taken along a plane including the central axis 82 of the inversely tapered waveguide 84 and the central axis 45c of the optical fiber 45. FIG. 28, the same reference numerals as those used in FIGS. 1 and 24 have the same functions and the same arrangement. In FIG. 28, description will be made assuming that the cross-sectional shape of the light transmission region 19 of the inversely tapered waveguide 84 is a square.

  The inverted tapered waveguide 84 has the same configuration as the tube waveguide 14 and has the same function. The difference between the reverse tapered waveguide 84 and the tube waveguide 14 is that the area of the cross-sectional shape of the optical transmission region 19 is monotonously decreased from the incident end 15 to the exit end 16.

  The optical transmitter 108 connects the reverse tapered waveguide 84 and the optical fiber 45 so that the central axis 62 and the central axis 45c are parallel to each other. The inversely tapered waveguide 84 can equalize and expand the FFP of the signal light A from the light emitting element 11 and couple it to the optical coupling range of the incident end 46 of the optical fiber 45.

  Therefore, even if the optical transmission device 108 is an optical fiber having a short optical path length and a bent state, the optical transmission device 108 can stably transmit data regardless of the relative position between the optical fiber and the light receiving element.

(Embodiment 7)
For the optical transmission device 106 in FIG. 26, a simulation was performed on the dependency between the FFP of light from the light emitting element 11 and the optical axis position of the signal light A at the output end 16 of the tapered waveguide 64.

  The simulation conditions are as follows. The light emitting surface of the light emitting element 11 is a circle having a diameter of 0.02 mm. The surface of the light transmission region 19 at the incident end 15 of the tapered waveguide 64 is a square having a side of 0.127 mm. The surface of the light transmission region 19 at the exit end 16 of the tapered waveguide 64 is a square having a diagonal of 0.14 mm. The optical path length of the tapered waveguide 64 is 3 mm.

  The optical axis positions F-0 to F-4 of the signal light A from the light emitting element 11 at the incident end 15 are shown in FIG. FIG. 29 is a view on the surface of the incident end 15 of the tapered waveguide 64. 29, the same reference numerals as those used in FIG. 1, FIG. 22, FIG. 24, and FIG. The intersection of the central axis 62 of the tapered waveguide 64 and the surface of the incident end 15 is the origin (0, 0), the direction from the incident end 15 to the output end 16 of the central axis 62 is the positive Z direction, and from the bottom of FIG. The upward direction is the positive direction of Y, and the right to left direction is the positive direction of X. The optical axis position F-0 is coordinates (0, 0), the optical axis position F-1 is coordinates (0.1, 0), the optical axis position F-2 is coordinates (0, 0.1), and the optical axis position F. −3 is coordinates (−0.1, 0), and the optical axis position F-4 is coordinates (0, −0.1). The unit of coordinates is mm.

  The simulation results of the FFP at the exit end 16 of the tubular waveguide 14 of the signal light A incident on the optical axis positions F-0, F-1, F-3, and F-4 of the entrance end 15 are shown in FIGS. 31, FIG. 32 and FIG. 33. In the simulation results, the FFP light intensity is displayed in hue. In FIGS. 30 to 33, the light intensity increases from brown to white.

  As a result of FIGS. 30 to 33, the FFP is uniformed regardless of the position of the signal light A from any position of the optical axis, and the influence of the position of the optical axis of the signal light A is small.

  Therefore, the optical transmitter 106 equalizes the FFP of the signal light A regardless of the relative position between the light emitting element 11 and the tapered waveguide 64 and emits the outgoing light B having a uniform light intensity distribution from the outgoing end 16. be able to.

(Embodiment 8)
The incident position of light in the conventional case in which light from a light emitting element is directly coupled to one end of an optical fiber and in the case of the present invention in which light is coupled by inserting the tubular waveguide between the light emitting element and the optical fiber A simulation was performed on the dependence of NFP on the other end of the optical fiber.

  FIG. 34 shows a conceptual diagram of a conventional optical transmitter 114 that performs simulation. The optical transmission device 114 includes the light emitting element 11 and the optical fiber 45. 34, the same reference numerals as those used in FIGS. 1 and 26 have the same functions and the same arrangement.

  The optical transmission device 114 connects the light emitting element 11 and the incident end 46 of the optical fiber 45. The signal light A from the light emitting element 11 is coupled to the incident end 46 of the optical fiber 45, propagates through the optical fiber 45, and exits from the exit end 47.

  On the other hand, FIG. 35 shows a conceptual diagram of an optical transmission apparatus 115 which is another embodiment according to the present invention for performing simulation. The optical transmitter 115 includes the light emitting element 11, the tapered waveguide 64, and the optical fiber 45. 35, the same reference numerals as those used in FIGS. 1, 22 and 26 have the same functions and the same arrangement.

  The optical transmitter 115 connects the light emitting element 11, the tapered waveguide 64, and the optical fiber 45 as described in the optical transmitter 106 of FIG. The tapered waveguide 64 emits outgoing light B from the outgoing end 16 as described with reference to FIG. The outgoing light B is coupled to the incident end 46 of the optical fiber 45, propagates through the optical fiber 45, and exits from the outgoing end 47.

  The simulation conditions are as follows. The optical fiber 45 has a core diameter of 0.24 mm, a diameter from the clad surface covering the core to 0.25 mm, and an optical path length from the incident end 46 to the output end 47 of 1 cm. In order to give the optical fiber 45 a bent state, the optical fiber 45 is bent uniformly along a circle having a radius of 5 mm from the entrance end 46 to the exit end 47.

  The central axis direction of the optical fiber 45 is taken as the Z direction, and the direction in which light propagates from the incident end 46 to the outgoing end 47 is taken as the positive direction of Z. Further, in the cross section perpendicular to the Z direction of the optical fiber 45, the radial direction of the circle having the radius of 5 mm is defined as the X direction, and the center direction of the circle is defined as the positive direction of X. Further, in the cross section, the direction perpendicular to the X direction and the Z direction is defined as the Y direction, and the front direction from the back side in FIGS. 34 and 35 is defined as the positive Y direction.

  FIG. 36 shows optical axis positions F-0 to F-4 of the signal light A from the light emitting element 11 at the incident end 46 in the optical transmitter 114 of FIG. 36, the same reference numerals as those used in FIG. 1, FIG. 25, FIG. 26, and FIG. In FIG. 36, the Z direction is positive from the front side of the drawing to the back side. If the intersection of the central axis 45c of the optical fiber 45 and the plane of the incident end 46 is the origin (0, 0), the optical axis position F-0 is the coordinate (0, 0), and the optical axis position F-1 is the coordinate ( 0.1,0), the optical axis position F-2 is coordinate (0,0.1), the optical axis position F-3 is coordinate (-0.1,0), and the optical axis position F-4 is coordinate (0). , −0.1). The unit of coordinates is mm.

  In the optical transmitter 115 of FIG. 35, the position of the optical axis of the signal light A from the light emitting element 11 at the incident end 15 of the tapered waveguide 64 is the same as in FIG. Further, the central axis 62 of the tapered waveguide 64 and the central axis 45 c of the optical fiber 45 coincide at the incident end 46.

  In the optical transmitter 114 of FIG. 34, the results of simulating NFP at the output end 47 of the optical fiber 45 of the signal light A incident on the optical axis positions F-0, F-1, F-3, and F-4 are respectively shown. 37, 38, 39 and 40. In addition, in the optical transmission device 115 of FIG. 35, the result of simulating NFP at the emission end 47 of the optical fiber 45 of the signal light A incident on the optical axis positions F-0, F-1, F-3, and F-4 is shown. They are shown in FIGS. 41, 42, 43 and 44, respectively. In the simulation results, the light intensity of NFP is displayed in hue. In FIGS. 37 to 44, the light intensity increases from brown to white.

Since the optical fiber 45 is bent, the signal light A is biased in the negative X direction, and the NFP at the emission end 47 has a strong light intensity in the negative X direction as shown in FIGS.
In particular, in the case of the optical transmitter 114 that directly inputs the signal light A to the optical axis positions F-0, F-3, and F-4, as shown in FIGS. 37, 39, and 40, the output end 47 of the optical fiber 45 is provided. , The amount of light from the position in the positive direction of X is small, and the light receiving element may not be able to receive a sufficient amount of light.

  Even in the case of the optical transmitter 114, the signal light A that has entered the optical axis position F-1 is diffused in the negative direction of X because the signal light A that propagates due to the bending of the optical fiber 45 is diffused in FIG. Thus, the NFP at the emission end 47 becomes uniform.

  Therefore, the NFP at the emission end 47 of the optical transmitter 114 is greatly affected by the bending of the optical fiber and the optical axis position of the signal light A.

  On the other hand, when the signal light A is coupled to the optical fiber 45 via the tapered waveguide 64, the tapered waveguide 64 couples the outgoing light B to the optical coupling range of the incident end 46 of the optical fiber 45, so The NFP at 47 is obtained by superimposing the NFP that the light incident from each position within the optical coupling range exhibits at the output end 47.

  Therefore, as described with reference to FIG. 38, the light from the positive X position of the incident end 46 exhibits a uniform NFP. Therefore, the NFP at the output end 47 of the optical transmission device 115 is as shown in FIGS. In addition, the influence of the bending of the optical fiber and the optical axis position of the signal light A can be reduced.

  Next, the present invention will be described in more detail with simulation results showing the dependence between the incident position of the outgoing light B at the incident end 46 of the optical fiber 45 and the position of the light receiving element at the outgoing end 47.

  A light receiving element that receives optical data to be transmitted is connected to the emission end 47 of the optical fiber 45 of the optical transmission device 114 and the optical transmission device 115. An example of the light receiving element is a photodiode (PD) having a circular light receiving surface 161 having a diameter of 0.1 cm. Similar to the relationship between the light emitting element and the optical fiber, the center axis of the optical fiber and the center position of the light receiving surface of the light receiving element may be different even if the light receiving element and the optical fiber are aligned. FIGS. 45 and 46 show the relative positions of the output end 47 of the optical fiber 45 and the light receiving surface 161 of the light receiving element.

  FIG. 45 is a diagram in the case where the center axis of the optical fiber 45 coincides with the center of the light receiving surface 161 of the light receiving element, that is, the center of the light receiving surface 161 of the light receiving element is at the origin of the surface of the emission end 47.

  In FIG. 46, the center axis of the optical fiber 45 and the center of the light receiving surface 161 of the light receiving element are different, that is, the center of the light receiving surface 161 of the light receiving element is at the coordinates (0.05, 0) of the surface of the emission end 47. FIG.

  45 shows the results of simulating the amount of light that can be received by the light receiving element for each optical axis position of the outgoing light B at the incident end 46 of the optical fiber 45. The positional relationship shown in FIG. 45 is shown in Table 1, and the positional relationship shown in FIG. Is shown in Table 2. The upper stage of Tables 1 and 2 is the optical axis position of the outgoing light B at the incident end 46 of the optical fiber 45, and the numerical values in the middle stage are the light quantity of the outgoing light B incident on the optical fiber 45 and the light receiving element in the case of the optical transmitter 114. The ratio of the amount of light that can be received, and the lower numerical value indicate the ratio of the amount of outgoing light B incident on the optical fiber 45 and the amount of light that can be received by the light receiving element in the case of the optical transmitter 115. The ratio between the amount of emitted light B and the amount of light that can be received by the light receiving element is indicated by an attenuation amount, and its unit is dB.

  When the relative position between the optical fiber 45 and the light receiving surface 161 of the light receiving element is as shown in FIG. 45, the attenuation amount of the optical transmission device 114 varies greatly depending on the optical axis position of the signal light A. The difference between the optical axis position 3 with the largest attenuation and the optical axis position 4 with the smallest attenuation is 3.54 dB. On the other hand, the difference in the attenuation amount of the optical transmitter 115 is small at the optical axis position of the signal light A. The difference between the optical axis position 4 with the largest attenuation and the optical axis position 1 with the smallest attenuation is 0.16 dB.

  When the relative position between the optical fiber 45 and the light receiving surface 161 of the light receiving element is as shown in FIG. 46, the attenuation amount of the optical transmitter 114 is significantly affected by the optical axis position of the signal light A. The difference between the optical axis position 3 with the largest attenuation and the optical axis position 4 with the smallest attenuation is 44.96 dB. On the other hand, the attenuation amount of the optical transmission device 115 has a small difference in the optical axis position of the signal light A, and a difference between the optical axis position 3 having the largest attenuation amount and the optical axis position 1 having the smallest attenuation amount is 2. .22 dB.

  The results in Tables 1 and 2 show that when the signal light A of the light emitting element 11 is directly incident on the optical fiber 45, the optical axis position of the signal light A, the bending state of the optical fiber 45, and the position of the light receiving surface 161 of the light receiving element. The influence is large, indicating that the amount of light that can be received by the light receiving element may decrease. That is, it becomes impossible to transmit data stably between modules.

  On the other hand, by arranging the tapered waveguide 64, the attenuation amount is less affected by the bending of the optical fiber 45, the optical axis position of the signal light A, and the position of the light receiving surface 161 of the light receiving element. Can stably transmit data.

  Therefore, the optical transmission device according to the present invention is stable regardless of the relative position between the optical fiber and the light receiving element, even if the optical fiber has a short optical path length and the bending state varies by arranging the tube-type waveguide. Data transmission.

  The optical transmitter according to the present invention can be used as a lighting device or a laser marking device.

1 is a conceptual diagram of an optical transmission device 101 according to an embodiment of the present invention. 3 is a diagram of a cross-sectional shape (shape 1) of an optical waveguide region 19. FIG. It is a figure of the cross-sectional shape (shape 2) of the optical waveguide region 19. FIG. 4 is a diagram of a cross-sectional shape (shape 3) of the optical waveguide region 19. FIG. 6 is a diagram of a cross-sectional shape (shape 4) of the optical waveguide region 19. FIG. 6 is a diagram of a cross-sectional shape (shape 5) of the optical waveguide region 19. FIG. 6 is a diagram of a cross-sectional shape (shape 6) of the optical waveguide region 19. FIG. 6 is a diagram of a cross-sectional shape (shape 7) of the optical waveguide region 19. FIG. It is a figure of the cross-sectional shape (shape 8) of the optical waveguide region 19. FIG. 6 is a diagram of a cross-sectional shape (shape 9) of the optical waveguide region 19. FIG. It is a figure of the cross-sectional shape (shape 10) of the optical waveguide region 19. FIG. 6 is a diagram of a cross-sectional shape (shape 11) of the optical waveguide region 19. FIG. It is a figure of the cross-sectional shape (shape 12) of the optical waveguide region 19. FIG. It is a figure of the cross-sectional shape (shape 13) of the optical waveguide region 19. FIG. It is a figure of the cross-sectional shape (shape 14) of the optical waveguide region 19. FIG. It is a figure of the cross-sectional shape (shape 15) of the optical waveguide region 19. FIG. It is a figure of the cross-sectional shape (shape 16) of the optical waveguide region 19. FIG. It is a figure of the cross-sectional shape (shape 17) of the optical waveguide region 19. FIG. It is a figure of the cross-sectional shape (shape 18) of the optical waveguide region 19. It is a figure of the cross-sectional shape (shape 19) of the optical waveguide region 19. FIG. It is a figure of the cross-sectional shape (shape 20) of the optical waveguide region 19. FIG. FIG. 4 is a diagram showing a relative position relationship between an incident end 15 of a tubular waveguide 14 and a light emitting surface 11a of a light emitting element 11. It is a conceptual diagram of the optical transmission apparatus 103 which is other embodiment which concerns on this invention. It is a conceptual diagram of the optical transmission apparatus 104 which is other embodiment which concerns on this invention. FIG. 6 is a diagram showing a relative position relationship between an incident end 46 of an optical fiber 45 and an exit end 16 of a tubular waveguide 14. It is a conceptual diagram of the optical transmission apparatus 106 which is other embodiment which concerns on this invention. It is a conceptual diagram of the optical transmission apparatus 107 which is other embodiment which concerns on this invention. It is a conceptual diagram of the optical transmission apparatus which is other embodiment which concerns on this invention. FIG. 5 is a diagram showing the optical axis position of the signal light A at the incident end 15. The FFP at the output end 16 of the tapered waveguide 64 of the signal light A is a result of simulation. The FFP at the output end 16 of the tapered waveguide 64 of the signal light A is a result of simulation. The FFP at the output end 16 of the tapered waveguide 64 of the signal light A is a result of simulation. The FFP at the output end 16 of the tapered waveguide 64 of the signal light A is a result of simulation. It is a conceptual diagram of the conventional optical transmitter 114. It is a conceptual diagram of the optical transmission apparatus 115 which is other embodiment which concerns on this invention. FIG. 6 is a diagram showing the optical axis position of signal light A at the incident end 46 of the optical fiber 45. It is the result of the simulation of NPF at the emission end 47 when the signal light A is directly coupled to the optical fiber 45. It is the result of the simulation of NPF at the emission end 47 when the signal light A is directly coupled to the optical fiber 45. It is the result of the simulation of NPF at the emission end 47 when the signal light A is directly coupled to the optical fiber 45. It is the result of the simulation of NPF at the emission end 47 when the signal light A is directly coupled to the optical fiber 45. This is a result of NPF simulation at the emission end 47 when the signal light A is coupled to the optical fiber 45 through the tapered waveguide 64. This is a result of NPF simulation at the emission end 47 when the signal light A is coupled to the optical fiber 45 through the tapered waveguide 64. This is a result of NPF simulation at the emission end 47 when the signal light A is coupled to the optical fiber 45 through the tapered waveguide 64. This is a result of NPF simulation at the emission end 47 when the signal light A is coupled to the optical fiber 45 through the tapered waveguide 64.

Explanation of symbols

101, 103, 104, 106, 107, 108, 114, 115 Optical transmission device 11 Light emitting element 11a Light emitting surface 12 of light emitting element 11 Central axes 14, 34, 34a, 34b Tube-shaped waveguide 15 Incident end 16 Emission end 18 Reflection Surface 19 Optical waveguide regions 22, 52 Assembly accuracy 26, 56 Region 45 Optical fiber 45a Core 45b Clad 45c Center axis 46 Entrance end 47 Exit end 61 Parallel lines 62, 72, 82 Center axes 64, 74 Tapered waveguide 84 Reverse taper Type waveguide A Signal light B Emission light E Light F-0 to 4 Optical axis position k of signal light A Number of mirror reflections or total reflections α Light emission angle β Taper angle θ ₀ Incident angle θ ₁ Emission angle θ ₂ Incident angle θ _c Critical angle

Claims (10)

A light emitting element;
A tube-shaped waveguide having a polygonal cross-sectional shape perpendicular to the light propagation direction of an optical waveguide region in which light from the light emitting element incident on the incident end propagates to the exit end by specular reflection or total reflection;
An optical transmission device comprising: A light emitting element;
A tube-shaped waveguide whose cross-sectional shape perpendicular to the light propagation direction of the optical waveguide region that propagates light from the light-emitting element incident on the incident end to the output end by specular reflection or total reflection is a rounded polygon;
An optical transmission device comprising: A light emitting element;
The cross-sectional shape perpendicular to the light propagation direction of the optical waveguide region that propagates the light from the light emitting element incident on the incident end to the output end by specular reflection or total reflection is surrounded by a single closed curve having a plurality of curvatures. A tube-shaped waveguide that is shaped,
An optical transmission device comprising: A light emitting element;
The cross-sectional shape perpendicular to the light propagation direction of the optical waveguide region that propagates the light from the light-emitting element incident on the incident end to the output end by specular reflection or total reflection is surrounded by connecting the ends of a plurality of curves. A tubular waveguide having a shape with a singular point at a connection point of the plurality of curves,
An optical transmission device comprising: A light emitting element;
The shape of the cross section perpendicular to the light propagation direction of the optical waveguide region that propagates the light from the light emitting element incident on the incident end to the output end by specular reflection or total reflection is at least one end of a line segment and at least one curve A tubular waveguide having a shape surrounded by connecting the ends of
An optical transmission device comprising: One end is connected to the exit end of the tube-type waveguide, and further comprises a multimode type optical fiber in which light from the tube-type waveguide enters the core,
6. The optical waveguide region at the exit end face of the tubular waveguide has a size contained in a cross section of a core at the one end face of the optical fiber. Any optical transmitter.   The area of the cross section perpendicular | vertical to the propagation direction of the light of the said optical waveguide area | region of the said tubular waveguide is monotonically decreasing from the said incident end to the said output end, The any one of Claim 1 to 6 characterized by the above-mentioned. Optical transmitter.   The reduction rate of the area of the optical waveguide region of the tube-shaped waveguide in a cross section perpendicular to the light propagation direction with respect to the distance in the light propagation direction decreases from the incident end toward the output end. Item 8. The optical transmission device according to Item 7.   The area of the cross section perpendicular | vertical to the propagation direction of the light of the said optical waveguide area | region of the said tubular waveguide is monotonically increasing toward the said output end from the said incident end, The Claim 1 to 6 characterized by the above-mentioned. Any optical transmitter. The shape of the cross section perpendicular to the light propagation direction of the optical waveguide region in one section of the tubular waveguide and the shape of the cross section perpendicular to the light propagation direction of the optical waveguide region in the other section of the tubular waveguide The optical transmission device according to claim 1, wherein the optical transmission devices have different shapes.

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