JP3725406B2

JP3725406B2 - Optical coupling device

Info

Publication number: JP3725406B2
Application number: JP2000220218A
Authority: JP
Inventors: 貞雄野田
Original assignee: サンクス株式会社
Priority date: 2000-07-21
Filing date: 2000-07-21
Publication date: 2005-12-14
Anticipated expiration: 2020-07-21
Also published as: JP2002040299A

Description

【０００１】
【発明の属する技術分野】
本発明は、発光素子からの光を光ファイバへと導く光結合装置に関する。
【０００２】
【従来の技術】
この種の光結合装置の従来例として、図４に示したものは、ＬＥＤチップ３を透明樹脂製のハウジング１でパッケージしてなる発光素子９のうちハウジング１の上面６に、光ファイバ５の入光面５Ａを接合して、ＬＥＤチップ３から射出された光を、光ファイバ５に入光させる構成をなす。
【０００３】
しかしながら、上記のものでは、発光素子９から放射状に出射された光が、光ファイバ５内へ導かれないため、発光素子９と光ファイバ５との光結合効率が低いという欠点があった。これに対して、ハウジング１の上壁を薄くしＬＥＤチップ３と光ファイバ５との間隔（図４の寸法「ｄ」参照）を小さくすることで、発光素子９のＬＥＤチップ３からの光をより多く光ファイバ５に取り込むようにして、光結合効率の改善を図ったものがある。しかし、このものでは、薄くしたハウジング１の上壁に空気中の湿気などが浸透し、ＬＥＤチップ３の輝度が劣化するという別の不具合が生じる。
【０００４】
そこで、以下の従来例１〜３のように、発光素子から放射された光を、集光手段にて、光ファイバの基端面に集光するものが開発された。
まず、その従来例１（図示せず）は、発光素子と光ファイバとの間に凸レンズを設けて、発光素子から出射された光を前記凸レンズにて光ファイバに集光する構成をなす。また、従来例２は（特開平２−４９４７８号公報参照）、図５に示されており、ハウジング１に、集光手段としての凹面状反射面１Ｃを設けて、発光素子９から射出された光を、その凹面状反射面１Ｃで反射し、光ファイバ５の入光面５Ａに集光させている。さらに、図６に示した従来例３では（特開平４−２７７７０１号公報参照）、回転楕円面７を有する反射体８を設けて、その回転楕円面７の一方の焦点に発光素子９を配し、他方の焦点に光ファイバ（図示せず）の入光面を配した構成をなし、一方の焦点の発光素子９から射出した光を、前記回転楕円面７で反射して、他方の焦点の光ファイバに集光させている。
【０００５】
【発明が解決しようとする課題】
ところが、上記した従来例２及び従来例３のように、集光手段を反射面で構成したものは、発光素子から大きく側方に放射された光を集光するのには、適しているが、発光素子からあまり側方に広がらずに進んだ光を集光するのには適していない。また、従来例１のものは、その逆に、発光素子からあまり側方に広がらずに進んだ光を集光するのには適しているが、発光素子から大きく側方に放射された光を集光するのには、適していない。
【０００６】
そこで、例えば、従来例１のものにおいて、発光素子に対して、十分大きい凸レンズを設け、これによって発光素子からの大きく側方に放射された光を、より広範囲にわたって光ファイバに導入させる構成も考えられる。しかしながら、単に凸レンズを大きくしても、焦点距離が大きくなって、発光素子とレンズとの間の距離が離れ、結局、発光素子から大きく側方に放射された光を凸レンズに入射させることはできない。たとえ、発光素子とレンズとの間の距離を変えずに用いても、そのために収束点がレンズから遠のき、像が大きくなってしまうので、結局、効率的に光ファイバに光を導入することができない。また、仮に凸レンズで光を収束させても、凸レンズの縁のほうで収束された光は、中央付近で収束された光の収束点よりも、凸レンズから遠い位置に収束点があるため、像が大きくなってしまう。さらに、より多くの光を、凸レンズで収束させるには、凸レンズと発光素子との距離を大きく取る必要があり、すると、小型化に支障を来す。
【０００７】
本発明は、上記事情に鑑みてなされたもので、発光素子と光ファイバの結合効率を改善することが可能な光結合装置の提供を目的とする。
【０００８】
【課題を解決するための手段及び作用・効果】
上記目的を達成するために、請求項１の発明に係る光結合装置は、発光素子から射出された光を、発光素子と対向する光ファイバの基端側の入光面に導く光結合装置において、発光素子と光ファイバとの間に配され、発光素子から射出された光を透過して光ファイバに集光する透過型集光手段と、透過型集光手段の側方に配され、発光素子から放射状に射出された光を反射して光ファイバに集光する反射面を有した反射型集光手段とを備え、反射型集光手段の反射面を、回転楕円面で構成して、その回転楕円面の一方の焦点に、発光素子を配すると共に、他方の焦点に光ファイバの入光面を配し、発光素子及び光ファイバの間には、それらを繋ぐ軸線を中心とした回転体形状をなす透光部材が設けられ、透過型集光手段は、透光部材のうち発光素子に対面した入射面又は光ファイバに対面した出射面のうち少なくともいずれかの中央部分を凸レンズ状に張り出して構成され、反射型集光手段は、透光部材の外周面を回転楕円面にして構成するところに特徴を有する。
【０００９】
この構成では、発光素子からあまり側方に広がらずに出射された光は、透過型集光手段を透過して光ファイバに集光され、発光素子から大きく側方に広がるように放射された光は、反射型集光手段で反射してやはり光ファイバに集光される。これにより、発光素子からあまり側方に広がらずに出射された光と、発光素子から大きく側方広がるように放射された光の両方が、光ファイバに集光され、光の結合効率が向上する。しかも、一方の焦点に配された発光素子から出射された光は回転楕円面で反射して、他方の焦点に配された光ファイバの入光面に集光される。このように、２つの焦点を有した回転楕円面を用いているから、発光素子と光ファイバの入光面とを各焦点に配して互いに離すことができ、焦点が１つの反射面を用いた場合に比べて、発光素子と光ファイバの配置が容易になる。
【００１１】
このようにすれば、１つの透光部材に、透過型集光手段と反射型集光手段とを一体に備えて、コンパクトな構造にすることができ、かつ、発光素子及び光ファイバへの組み付けも容易になる。
【００１２】
また、請求項２の発明は、請求項１記載の光結合装置において、透光部材のうち入射面の周縁部分には、発光素子から透光部材の外周面へと向かう光が、ほぼ垂直に入射するように湾曲した透過面が形成され、透光部材のうち出射面の周縁部分には、透光部材の外周面から光ファイバへと向かう反射光が、ほぼ垂直に出射するように湾曲した透過面が形成されたところに特徴を有する。
【００１３】
この構成により、発光素子から放射状に広がった光や、透光部材の外周面で反射して集光された光が、透光部材のうち入射面又は出射面の周縁部分で、ほとんど屈折せずに透過し、集光点がばらつかないので、光の結合効率が向上する。
【００１４】
【発明の実施の形態】
＜第１実施形態＞
以下、本発明の第１実施形態について、図１を参照にしつつ説明する。図１において、符号１０は、発光素子であって、例えば、リードフレーム（図示せず）に実装された面発光型のＬＥＤチップ１２を、ハウジング１３でパッケージしてなる。このハウジング１３のうち図１において右側の端部は、透明樹脂にて、丸みを帯びた凸レンズ状に形成され、その曲面を出射面１６としている。
【００１５】
２０は、光ファイバであって、外周をシース２２で覆われている。そして、光ファイバ２０のうち基端側の入光面２１を、発光素子１０の出射面１６に対向させてある。より詳細には、光ファイバ２０の同軸線上に上記ＬＥＤチップ１２が位置するようにしてある。
【００１６】
３０は、透光部材であって、光ファイバ２０の軸線を中心とした回転体形状をなし、発光素子１０側に入射面３２を備える一方、光ファイバ２０側に出射面３６を備え、さらに、外周には、出射面３６側から入射面３２側に向けて緩やかに窄まった回転楕円面３５を備える。そして、回転楕円面３５の一方の焦点に、発光素子１０のＬＥＤチップ１２が配置され、他方の焦点に、光ファイバ２０の入光面２１が配置されている。
【００１７】
また、入射面３２の中央部分には、発光素子１０側に膨出した凸レンズ部３３が備えられ、入射面３２の周縁部分は、発光素子１０に向かうに従って凸レンズ部３３の周縁から透光部材３０の周面へと拡開した透過面３４となっている。
【００１８】
出射面３６は、やはり中央部分を光ファイバ２０側に膨出させて凸レンズ部３７を備え、出射面３６の周縁部分が、光ファイバ２０に向かうに従って凸レンズ部３７の周縁から斜め前方に向かって拡開する透過面３８となっている。
【００１９】
本実施形態の構成によれば、発光素子１０からあまり側方に広がらずに出射された光は、凸レンズ部３３，３７を透過して光ファイバ２０の入光面２１へと集光される。また、発光素子１０から大きく側方に広がるように放射された光は、透光部材３０の回転楕円面３５で反射してやはり光ファイバ２０の入光面２１へと集光される。これにより、発光素子１０からあまり側方に広がらずに出射された光と、発光素子１０から大きく側方に広がった光の両方が、光ファイバ２０に集光され、光の結合効率が向上する。ここで、発光素子１０から放射状に広がった光は、透光部材３０に入射するときには、その入射面３２の周縁部分に形成した透過面３４をほぼ垂直に貫通し、透光部材３０から出射されときには、透光部材３０の出射面３６の周縁部分に形成した透過面３４をほぼ垂直に貫通するから、透光部材３０の入射面３２及び出射面３６における屈折が抑えられるので、集光点がばらつかず、光の結合効率が向上する。
【００２０】
＜第２実施形態＞
本実施形態は、図２に示されており、前記第１実施形態を変形させたものである。即ち、本実施形態では、透光部材４０に備えた入射面４２が、発光素子１０における凸レンズ状の出射面１６に対応して凹面状に窪んだ構造をなし、この入射面４２に、発光素子１０の出射面１６を密着或いは接着させてある。これにより、発光素子１０と透光部材４０との間に、光学的に疎である空気層がほとんど介在しなくなり、もって、透光部材４０の入射面における反射をより効果的に抑えることができ、光の結合効率が向上する。
【００２１】
＜参考例＞
本実施形態は、本発明の技術的範囲には含まれない参考例であり、図３に示されており、回転楕円体形状の空間５１を有した反射体５０の内部のうち、楕円の一方の焦点に発光素子１０を配し、他方の焦点に光ファイバ２０の入光面２１を配してある。そして、反射体５０のうち空間５１の内面は、鏡面構造の回転楕円面５２をなして、発光素子１０から出射された光を、光ファイバ２０の入光面２１に集光する。また、発光素子１０と光ファイバ２０との間には、凸レンズ５３が配され、これにより、発光素子１０からあまり広がらずに放射され、光ファイバ２０に向かった光を、光ファイバ２０の軸芯に集光している。
【００２２】
＜他の実施形態＞
本発明は、実施形態に限定されるものではなく、上記以外にも要旨を逸脱しない範囲内で種々変更して実施することができる。
【図面の簡単な説明】
【図１】本発明の第１実施形態に係る光結合装置の側断面図
【図２】本発明の第２実施形態に係る光結合装置の側断面図
【図３】参考例に係る光結合装置の側断面図
【図４】従来の光結合装置の側断面図
【図５】従来例２の光結合装置の側断面図
【図６】従来例３の光結合装置の側断面図[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical coupling device that guides light from a light emitting element to an optical fiber.
[0002]
[Prior art]
As a conventional example of this type of optical coupling device, what is shown in FIG. 4 is a light emitting device 9 in which an LED chip 3 is packaged with a transparent resin housing 1. The light incident surface 5 </ b> A is joined, and the light emitted from the LED chip 3 is incident on the optical fiber 5.
[0003]
However, in the above, since the light emitted radially from the light emitting element 9 is not guided into the optical fiber 5, the optical coupling efficiency between the light emitting element 9 and the optical fiber 5 is low. On the other hand, the light from the LED chip 3 of the light emitting element 9 can be reduced by thinning the upper wall of the housing 1 and reducing the distance between the LED chip 3 and the optical fiber 5 (see the dimension “d” in FIG. 4). Some optical fibers are incorporated into the optical fiber 5 to improve the optical coupling efficiency. However, in this case, another problem arises that moisture in the air penetrates into the upper wall of the thinned housing 1 and the luminance of the LED chip 3 deteriorates.
[0004]
Therefore, as in the following conventional examples 1 to 3, the light that has been emitted from the light emitting element is collected on the base end face of the optical fiber by the condensing means.
First, Conventional Example 1 (not shown) has a configuration in which a convex lens is provided between a light emitting element and an optical fiber, and light emitted from the light emitting element is condensed on the optical fiber by the convex lens. Conventional example 2 (see Japanese Patent Application Laid-Open No. 2-49478) is shown in FIG. 5, and the housing 1 is provided with a concave reflecting surface 1 </ b> C as a condensing means and emitted from the light emitting element 9. The light is reflected by the concave reflecting surface 1 </ b> C and condensed on the light incident surface 5 </ b> A of the optical fiber 5. Further, in Conventional Example 3 shown in FIG. 6 (see Japanese Patent Laid-Open No. 4-277701), a reflector 8 having a spheroid 7 is provided, and a light emitting element 9 is arranged at one focal point of the spheroid 7. The light incident surface of an optical fiber (not shown) is arranged at the other focal point, and the light emitted from the light emitting element 9 at one focal point is reflected by the spheroid 7 and the other focal point is reflected. The optical fiber is focused.
[0005]
[Problems to be solved by the invention]
However, as in the conventional example 2 and the conventional example 3 described above, the condensing means constituted by the reflecting surface is suitable for condensing light radiated largely from the light emitting element. It is not suitable for condensing the light that has traveled from the light emitting element without spreading too much to the side. On the contrary, the conventional example 1 is suitable for condensing the light that has traveled from the light emitting element without spreading too much to the side, but the light emitted from the light emitting element to the side is greatly reduced. It is not suitable for collecting light.
[0006]
Therefore, for example, in the conventional example 1, a configuration in which a sufficiently large convex lens is provided for the light emitting element so that light radiated largely from the light emitting element to the side is introduced into the optical fiber over a wider range. It is done. However, even if the convex lens is simply enlarged, the focal length is increased, and the distance between the light emitting element and the lens is increased, so that the light emitted from the light emitting element largely to the side cannot be incident on the convex lens. . Even if it is used without changing the distance between the light emitting element and the lens, the converging point is far from the lens and the image becomes large, so in the end, light can be efficiently introduced into the optical fiber. Can not. Even if the light is converged with a convex lens, the light converged near the edge of the convex lens has a convergence point at a position farther from the convex lens than the convergence point of the light converged near the center. It gets bigger. Further, in order to converge more light with the convex lens, it is necessary to increase the distance between the convex lens and the light emitting element, which hinders downsizing.
[0007]
The present invention has been made in view of the above circumstances, and an object thereof is to provide an optical coupling device capable of improving the coupling efficiency between a light emitting element and an optical fiber.
[0008]
[Means for solving the problems and actions / effects]
In order to achieve the above object, an optical coupling device according to claim 1 is an optical coupling device that guides light emitted from a light emitting element to a light incident surface on a base end side of an optical fiber facing the light emitting element. A transmissive condensing means that is arranged between the light emitting element and the optical fiber, transmits the light emitted from the light emitting element and condenses it on the optical fiber, and is arranged on the side of the transmissive condensing means to emit light A reflection type condensing means having a reflection surface for reflecting the light emitted radially from the element and condensing it on the optical fiber, and the reflection surface of the reflection type condensing means is composed of a spheroid, A light emitting element is disposed at one focal point of the spheroid, and an optical fiber incident surface is disposed at the other focal point. Between the light emitting element and the optical fiber, rotation about an axis connecting them is performed. A translucent member having a body shape is provided, and the transmissive condensing means is a light emitting member of the translucent member The center part of at least one of the entrance surface facing the element or the exit surface facing the optical fiber is projected into a convex lens shape, and the reflection type condensing means uses the outer peripheral surface of the translucent member as a spheroidal surface. It has features in its construction .
[0009]
In this configuration, the light emitted from the light emitting element without spreading so much sideways is transmitted through the transmission type condensing means, collected on the optical fiber, and emitted from the light emitting element so as to spread widely to the side. Is reflected by the reflection type condensing means and is also condensed on the optical fiber. As a result, both the light emitted from the light emitting element without spreading sideways and the light emitted from the light emitting element so as to spread widely to the side are condensed on the optical fiber, and the light coupling efficiency is improved. . In addition, the light emitted from the light emitting element arranged at one focal point is reflected by the spheroid and condensed on the light incident surface of the optical fiber arranged at the other focal point. In this way, since the spheroid having two focal points is used, the light emitting element and the light incident surface of the optical fiber can be arranged at the respective focal points, and can be separated from each other. The arrangement of the light emitting element and the optical fiber is facilitated as compared with the case where the light emitting element is used.
[0011]
In this way, the transmissive condensing means and the reflective condensing means are integrally provided in one translucent member, so that a compact structure can be obtained, and the light emitting element and the optical fiber can be assembled. Will also be easier.
[0012]
According to a second aspect of the present invention, in the optical coupling device according to the first aspect, light directed from the light emitting element to the outer peripheral surface of the light transmitting member is substantially perpendicular to the peripheral portion of the incident surface of the light transmitting member. A transmissive surface curved so as to be incident is formed, and the reflected light from the outer peripheral surface of the translucent member toward the optical fiber is curved so as to be emitted substantially perpendicularly at the peripheral portion of the output surface of the translucent member. It is characterized in that a transmission surface is formed.
[0013]
With this configuration, light that spreads radially from the light emitting element or light that is reflected and collected by the outer peripheral surface of the light transmitting member is hardly refracted at the peripheral portion of the incident surface or the output surface of the light transmitting member. The light condensing point does not vary, so that the light coupling efficiency is improved.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
<First Embodiment>
Hereinafter, a first embodiment of the present invention will be described with reference to FIG. In FIG. 1, reference numeral 10 denotes a light emitting element. For example, a surface emitting LED chip 12 mounted on a lead frame (not shown) is packaged in a housing 13. The right end portion of the housing 13 in FIG. 1 is formed of a transparent resin into a rounded convex lens shape, and the curved surface thereof is used as an exit surface 16.
[0015]
Reference numeral 20 denotes an optical fiber whose outer periphery is covered with a sheath 22. The light incident surface 21 on the proximal end side of the optical fiber 20 is opposed to the light emitting surface 16 of the light emitting element 10. More specifically, the LED chip 12 is positioned on the coaxial line of the optical fiber 20.
[0016]
30 is a translucent member having a rotating body centered on the axis of the optical fiber 20 and having an incident surface 32 on the light emitting element 10 side, an output surface 36 on the optical fiber 20 side, On the outer periphery, there is provided a spheroid 35 that is gently constricted from the exit surface 36 toward the entrance surface 32. The LED chip 12 of the light emitting element 10 is disposed at one focal point of the spheroid 35, and the light incident surface 21 of the optical fiber 20 is disposed at the other focal point.
[0017]
In addition, a convex lens portion 33 bulging toward the light emitting element 10 is provided at the central portion of the incident surface 32, and a peripheral portion of the incident surface 32 extends from the periphery of the convex lens portion 33 toward the light emitting element 10. It becomes the permeation | transmission surface 34 expanded to the surrounding surface.
[0018]
The exit surface 36 is also provided with a convex lens portion 37 with its central portion bulging toward the optical fiber 20, and the peripheral portion of the exit surface 36 expands obliquely forward from the periphery of the convex lens portion 37 toward the optical fiber 20. It is a transparent surface 38 that opens.
[0019]
According to the configuration of the present embodiment, the light emitted from the light emitting element 10 without spreading so much sideways passes through the convex lens portions 33 and 37 and is collected on the light incident surface 21 of the optical fiber 20. Further, the light emitted from the light emitting element 10 so as to spread largely to the side is reflected by the spheroid 35 of the translucent member 30 and is condensed on the light incident surface 21 of the optical fiber 20. As a result, both the light emitted from the light emitting element 10 without spreading so much to the side and the light that has spread widely from the light emitting element 10 are condensed on the optical fiber 20 and the light coupling efficiency is improved. . Here, when the light spreading radially from the light emitting element 10 enters the light transmitting member 30, the light penetrates through the transmission surface 34 formed in the peripheral portion of the incident surface 32 substantially perpendicularly and is emitted from the light transmitting member 30. Sometimes, since the light passes through the transmission surface 34 formed at the peripheral portion of the emission surface 36 of the translucent member 30 almost vertically, refraction at the incident surface 32 and the emission surface 36 of the translucent member 30 is suppressed, so that the condensing point is The light coupling efficiency is improved without variation.
[0020]
Second Embodiment
This embodiment is shown in FIG. 2 and is a modification of the first embodiment. That is, in the present embodiment, the incident surface 42 provided in the translucent member 40 has a concave structure corresponding to the convex lens-shaped exit surface 16 of the light emitting element 10. Ten exit surfaces 16 are adhered or adhered. Thereby, the optically sparse air layer is hardly interposed between the light emitting element 10 and the translucent member 40, so that reflection on the incident surface of the translucent member 40 can be more effectively suppressed. , Light coupling efficiency is improved.
[0021]
< Reference example >
This embodiment is a reference example not included in the technical scope of the present invention, and is shown in FIG. 3. One of the ellipses of the inside of the reflector 50 having the spheroidal space 51 is shown in FIG. The light emitting element 10 is disposed at the focal point, and the light incident surface 21 of the optical fiber 20 is disposed at the other focal point. The inner surface of the space 51 of the reflector 50 forms a spheroidal surface 52 having a mirror surface structure, and condenses the light emitted from the light emitting element 10 on the light incident surface 21 of the optical fiber 20. In addition, a convex lens 53 is disposed between the light emitting element 10 and the optical fiber 20, thereby radiating light from the light emitting element 10 without spreading so much and directing the light toward the optical fiber 20 to the axis of the optical fiber 20. It is focused on.
[0022]
<Other embodiments>
The present invention is not limited to the embodiments, and can be implemented with various modifications other than those described above without departing from the scope of the invention.
[Brief description of the drawings]
Optical coupling according to a first side sectional view of an optical coupling device according to the second embodiment of the cross-sectional side view the present invention; FIG optical coupling device according to the embodiment [3] reference example of the present invention; FIG FIG. 4 is a side sectional view of a conventional optical coupling device. FIG. 5 is a side sectional view of an optical coupling device of Conventional Example 2. FIG. 6 is a side sectional view of an optical coupling device of Conventional Example 3.

Claims

In the optical coupling device that guides the light emitted from the light emitting element to the light incident surface on the base end side of the optical fiber facing the light emitting element,
A transmissive condensing means that is disposed between the light emitting element and the optical fiber and transmits the light emitted from the light emitting element and condenses the light on the optical fiber;
A reflective condensing means disposed on the side of the transmissive condensing means, and having a reflecting surface for reflecting the light emitted radially from the light emitting element and condensing the light on the optical fiber; The reflection surface of the type condensing means is composed of a spheroid, and the light emitting element is arranged at one focal point of the spheroid and the light incident surface of the optical fiber is arranged at the other focal point. ,
Between the light emitting element and the optical fiber, there is provided a translucent member having a rotating body shape around an axis connecting them,
The transmission type condensing means is configured by projecting at least one central portion of the light transmitting member on the incident surface facing the light emitting element or the light emitting surface facing the optical fiber into a convex lens shape,
The optical coupling device, wherein the reflection type condensing means is configured with an outer peripheral surface of the translucent member as a spheroid.

A curved transmission surface is formed on a peripheral portion of the incident surface of the light transmitting member so that light traveling from the light emitting element toward the outer peripheral surface of the light transmitting member is incident substantially perpendicularly.
In the translucent member, a transmissive surface curved so that reflected light from the outer peripheral surface of the translucent member toward the optical fiber is emitted almost vertically is formed at the peripheral portion of the output surface. The optical coupling device according to claim 1 .