JPS6057048B2 - graded lens - Google Patents
graded lensInfo
- Publication number
- JPS6057048B2 JPS6057048B2 JP55103397A JP10339780A JPS6057048B2 JP S6057048 B2 JPS6057048 B2 JP S6057048B2 JP 55103397 A JP55103397 A JP 55103397A JP 10339780 A JP10339780 A JP 10339780A JP S6057048 B2 JPS6057048 B2 JP S6057048B2
- Authority
- JP
- Japan
- Prior art keywords
- refractive index
- graded
- lens
- numerical aperture
- graded lens
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000003287 optical effect Effects 0.000 claims description 18
- 230000007423 decrease Effects 0.000 claims description 3
- 230000005540 biological transmission Effects 0.000 description 14
- 239000013307 optical fiber Substances 0.000 description 13
- 239000000835 fiber Substances 0.000 description 12
- 238000009826 distribution Methods 0.000 description 10
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 5
- 230000002093 peripheral effect Effects 0.000 description 4
- 238000004891 communication Methods 0.000 description 3
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 238000003384 imaging method Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 230000002238 attenuated effect Effects 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000002019 doping agent Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/42—Coupling light guides with opto-electronic elements
- G02B6/4201—Packages, e.g. shape, construction, internal or external details
- G02B6/4202—Packages, e.g. shape, construction, internal or external details for coupling an active element with fibres without intermediate optical elements, e.g. fibres with plane ends, fibres with shaped ends, bundles
- G02B6/4203—Optical features
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)
- Lenses (AREA)
- Optical Couplings Of Light Guides (AREA)
Description
【発明の詳細な説明】
本発明は、光ファイバとの結合効率が高くしかも入射
端側で高開口数を確保し得る新規な構造のグレーデツド
形レンズに関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a graded lens with a novel structure that has high coupling efficiency with an optical fiber and can ensure a high numerical aperture on the input end side.
近年、光ファイバの開発に伴い従来からある光学レン
ズの代りに中心側ほど屈折率が高く且つ径方向外周側に
向かうに従つて漸次屈折率が低くなつた丸棒状のグレー
ドデツド形レンズ（ロッドレンズ）が作り出され、光学
レンズよりも大幅にコンパクト化し得るために光ファイ
バの端末に接続する結像光学系や集光レンズ等として利
用されている。In recent years, with the development of optical fibers, instead of conventional optical lenses, round bar-shaped graded lenses (rod lenses) have been introduced, which have a higher refractive index toward the center and gradually lower toward the outer periphery in the radial direction. Since they can be made much more compact than optical lenses, they are used as imaging optical systems connected to the terminals of optical fibers, condensing lenses, etc.
ところで、伝送損失が最も少ないとされている石英系
ファイバは、他のファイバと比較して開口数が小さく即
ち光の入射角度の範囲が狭いため、通信用の信号光線を
伝送する場合には、光源からの光線のほんの一部しか送
ることができず、強力な光源が必要となる。By the way, silica fiber, which is said to have the lowest transmission loss, has a smaller numerical aperture than other fibers, that is, a narrow range of light incident angles, so when transmitting signal beams for communication, Only a small portion of the light rays from the light source can be transmitted, and a powerful light source is required.
又、この石英系ファイバをイメージファイバとして画像
伝送に使用した場合には、開口数が小さいため明るい画
像を伝送することができなかつた。しかも、光学系相互
の接続部でのこれら光学系の開口数が異なる場合には、
最も小さな開口数の光学系で光線の入射角が規定されて
しまうため、例え開口数の大きなグレーデツド形レンズ
を光線の導入側に使用しても、光ファイバ自体の開口数
が小さい場合には、このグレーデツド形レンズから光フ
ァイバへ入射する光線の一部が損失となつてしまい、結
合効率を低下させる原因となつていた。このような観点
から、本発明は光ファイバとの結合効率が高くしかも入
射端側て高開口数を確保し得る新規な構造のグレーデツ
ド形レンズを提供することを目的とする。Furthermore, when this quartz fiber is used as an image fiber for image transmission, it is not possible to transmit a bright image due to its small numerical aperture. Moreover, if the numerical apertures of these optical systems differ at the joints between the optical systems,
Since the angle of incidence of the light ray is determined by the optical system with the smallest numerical aperture, even if a graded lens with a large numerical aperture is used on the light introduction side, if the numerical aperture of the optical fiber itself is small, A portion of the light beam incident on the optical fiber from this graded lens becomes a loss, causing a reduction in coupling efficiency. From this viewpoint, an object of the present invention is to provide a graded lens with a novel structure that has high coupling efficiency with an optical fiber and can ensure a high numerical aperture on the input end side.
この目的を達成する本発明のグレーデツド形レンズにか
かる構成は、中心の屈折率に対して径方向外周側の屈折
率ほど漸次低くなつた一定な径のグレーデツド形レンズ
において、その一端面側の屈折率に対して光軸方向と平
行な方向に沿つた他端面側の屈折率ほど低く、しかも前
記一端面側における前記中心と径方向外周側との屈折率
差よりも前記他端面側における前記中心と径方向外周側
との屈折率差の方を大きくしたことを特徴とする。The configuration of the graded lens of the present invention that achieves this objective is such that the graded lens has a constant diameter in which the refractive index of the center is gradually lowered toward the outer periphery in the radial direction. The refractive index on the other end surface side along the direction parallel to the optical axis direction is lower than the refractive index difference between the center on the one end surface side and the radial outer peripheral side. It is characterized by a larger difference in refractive index between the outer peripheral side in the radial direction and the outer peripheral side in the radial direction.
以下、本発明によるグレーデツド形レンズを光伝送路に
応用した一実施例について、その入射端部の概略原理を
表わす第１図を参照しながら詳細に説明すると、中心に
対して径方向外周側の屈折率ほど漸次低くなつたグレー
デツド形レンズ１の一端面が単一モード伝送用光ファイ
バ２の端面に突き合わせた状態で接着されている。Hereinafter, an embodiment in which the graded lens according to the present invention is applied to an optical transmission line will be described in detail with reference to FIG. 1, which shows the general principle of the entrance end. One end surface of a graded lens 1 whose refractive index gradually decreases is bonded to the end surface of a single mode transmission optical fiber 2 in a butt state.
このグレーデツド形レンズ１の屈折率分布は、図中、一
点鎖線で示す光軸３と平行に沿つた方向において、一端
面側の方が光線４の入射する他端面側よりも常に高くな
つているが、中心と径方向外周側との屈折率差Δｎは一
端面側の方よりも他端面側の方が大きくなつている。つ
まり、他端面側の開口数の方が一端面側の開口数よりも
大きくなつており、本実施例におけるグレーデツド形レ
ンズ１の径方向に沿つた屈折率分布を第２図に示すが、
図中の上側の抛物線が一端面の部分での屈折率分布を表
わし、下側の抛物線が他端面の部分での屈折率分布を表
わす。なお、光軸３に平行に沿つた方向の屈折率分布は
、先にも述べたように一端面から他端面へ向けて直線状
に連続して減少した状態となつている。従つて、θ２な
る入射角でグレーデツド形レンズ１の他端面から入射し
た光線４は、その振幅が次第に減衰したようになり、θ
２より小さなθ１なる射出角でその一端面から単一モー
ド伝送用光ファイバ２のコア部５に入射する。この場合
、光線４の進行方向前方ほど高屈折率となつているため
、グレーデツド形レンズ１内を曲折しながら進行する光
線４の外部への滲み出しが全くなく、他端面の開口数で
規定される最大人射角でグレーデツド形レンズ１に入射
した光線は、全部が単一モード伝送用光ファイバ２のコ
ア部５へ送り込まれることとなる。従つて、このグレー
デツド形レンズ１は極めて効率の高い集光レンズとして
機能し、強力な光信号をコア部５内へ導くことが可能で
ある。なお、本実施例では単一モード光ファイバの入射
端部について説明したが、その射出端部にも本発明によ
るグレーデツド形レンズを装着するようにしてもよい。
次に、本発明による別なグレーデツド形レンズを光伝送
路に応用した他の一実施例について第３図及び第４図を
参照しながら説明する。The refractive index distribution of this graded lens 1 is always higher on one end surface side than on the other end surface side where the light ray 4 is incident, in the direction parallel to the optical axis 3 indicated by the dashed line in the figure. However, the refractive index difference Δn between the center and the outer peripheral side in the radial direction is larger on the other end surface side than on the one end surface side. In other words, the numerical aperture on the other end surface side is larger than the numerical aperture on the one end surface side, and the refractive index distribution along the radial direction of the graded lens 1 in this example is shown in FIG.
The upper parabola in the figure represents the refractive index distribution at one end surface, and the lower paramolecular line represents the refractive index distribution at the other end surface. Note that the refractive index distribution in the direction parallel to the optical axis 3 is in a state in which it decreases linearly and continuously from one end surface to the other end surface, as described above. Therefore, the amplitude of the light ray 4 incident from the other end surface of the graded lens 1 at an incident angle of θ2 becomes gradually attenuated, and the angle of incidence becomes θ2.
The light enters the core portion 5 of the single mode transmission optical fiber 2 from one end face thereof at an exit angle of θ1 smaller than 2. In this case, since the refractive index is higher toward the front in the traveling direction of the light ray 4, the light ray 4 traveling while bending inside the graded lens 1 does not seep out to the outside at all, and the numerical aperture of the other end surface is defined. All of the light rays incident on the graded lens 1 at the maximum human incidence angle are sent into the core portion 5 of the single mode transmission optical fiber 2. Therefore, this graded lens 1 functions as an extremely efficient condensing lens, and is capable of guiding a strong optical signal into the core portion 5. Although the present embodiment has been described with respect to the input end of a single mode optical fiber, the graded lens according to the present invention may also be attached to the exit end.
Next, another embodiment in which another graded lens according to the present invention is applied to an optical transmission line will be described with reference to FIGS. 3 and 4.
本実施例の概略原理を表わす第３図に示すように、本実
施例では開口数の異なつた複数個（図ては四個）のグレ
ーデツド形レンズ１１，１２，１３，１４を開口数の順
に接続し、最も開口数の小さなグレーデツド形レンズ１
１をイメージファイバ１６の端面に接続させている。従
つて、本実施例では四個のグレーデツド形レンズ１１，
１２，１３，１４を組み合わせて一つのグレーデツド形
レンズ（結像レンズ）１５が構成され、画像伝送に供さ
れる。本実施例では先に説明したグレーデツド形レンズ
１と異なり、従来と同じものを使用している。つまり、
光軸方向の屈折率分布は変化しないものであるが、これ
らの径方向屈折率分布を表わす第４図に示すように、開
口数の最も小さいグレーデツド形レンズ１１が最高の屈
折率を有し、開口数の最も大きなグレーデツド形レンズ
１４が最低の屈折率となつている。図中の符号でΔＮ２
の屈折率差を有するものがグレーデツド形レンズ１２に
相当し、Δ〜の屈折率差がグレーデツド形レンズ１３に
相当する。前述した実施例のように光軸方向に連続的に
屈折率を変化させてグレーデツド形レンズ１を製造する
ことは、例えば気相軸付け法においてはドーパントの供
給量とその分布とを時間的に変化させなければならず比
較的めんどうな製造手順となるが、本実施例では種類の
異なるグレーデツド形レンズ１１，１２，１３，１４を
組み合わせるだけて済み、しかも両端部の開口数の差の
制御も比較的容易である。このような観点から、前述の
グレーデツド形レンズ１を本実施例のように複数個接合
して一個に形成することも可能である。本実施例におい
ても、入射光線１７はその進行方向に屈折率が高くなつ
ているため、外方への滲み出しがほとんどなく、次第に
中央部に収束して小さな射出角でイメージファイバ１６
に入射する。As shown in FIG. 3, which shows the general principle of this embodiment, in this embodiment, a plurality of (four in the figure) graded lenses 11, 12, 13, and 14 with different numerical apertures are arranged in order of numerical aperture. Graded lens with the smallest numerical aperture 1
1 is connected to the end face of the image fiber 16. Therefore, in this embodiment, four graded lenses 11,
12, 13, and 14 are combined to form one graded lens (imaging lens) 15, which is used for image transmission. This embodiment uses the same graded lens 1 as the conventional one, unlike the graded lens 1 described above. In other words,
Although the refractive index distribution in the optical axis direction does not change, as shown in FIG. 4, which shows these radial refractive index distributions, the graded lens 11 with the smallest numerical aperture has the highest refractive index, The graded lens 14 with the largest numerical aperture has the lowest refractive index. ΔN2 with the symbol in the figure
A lens having a refractive index difference of .DELTA. corresponds to the graded lens 12, and a refractive index difference of .DELTA. to the graded lens 13. Manufacturing the graded lens 1 by continuously changing the refractive index in the optical axis direction as in the above-described embodiment means that, for example, in the vapor phase axial method, the amount of dopant supplied and its distribution can be changed over time. Although the manufacturing procedure is relatively troublesome as the lens must be changed, in this embodiment, it is only necessary to combine graded lenses 11, 12, 13, and 14 of different types, and it is also possible to control the difference in numerical aperture between the two ends. It's relatively easy. From this point of view, it is also possible to bond a plurality of the graded lenses 1 described above to form one lens as in this embodiment. In this embodiment as well, since the refractive index of the incident light ray 17 increases in its traveling direction, there is almost no outward oozing, and it gradually converges in the center and enters the image fiber 16 at a small exit angle.
incident on .
このため、開口数の小さいファイバで構成したイメージ
ファイバ１６を使用しても明るい画像を伝送することが
可能である。なお、このイメージファイバ１６の射出端
部にも本発明のグレーデツド形レンズを接続することに
よつて、明るさを任意に設定することができる。このよ
うに本発明によると、グレーデツド形レンズの両端面の
開口数を変える一方、開口数の大きな端面から入射した
光線が途中で外部に滲み出して損失増加とならないよう
に光線の進行方向前方ほど高屈折率としたので、開口数
の小さな石英系ファイバを使用しても実際には大きな開
口数を持つたものとして利用でき、従つて通信用光伝送
路に応用した場合には強大な光信号を光ファイバ内に取
り入れることが可能であり、又、画像伝送路に応用した
場合には明るい画像を伝送することができる。Therefore, it is possible to transmit a bright image even when using the image fiber 16 made of a fiber with a small numerical aperture. By connecting the graded lens of the present invention to the exit end of the image fiber 16, the brightness can be set arbitrarily. As described above, according to the present invention, while changing the numerical aperture of both end faces of a graded lens, the numerical aperture is changed toward the front in the direction of travel of the light ray so that the light ray incident from the end face with a large numerical aperture does not seep out to the outside on the way and increase loss. Because it has a high refractive index, even if a silica-based fiber with a small numerical aperture is used, it can actually be used as one with a large numerical aperture, and therefore, when applied to optical transmission lines for communication, it can generate strong optical signals. can be incorporated into an optical fiber, and when applied to an image transmission path, bright images can be transmitted.
第１図は本発明のよるグレーデツド形レンズの一実施例
を単一モード伝送用光ファイバに接続した場合の通信用
光伝送路における入射端部の光線の進行原理を表わす幾
何原理図、第２図はこのグレーデツド形レンズの両端面
における径方向屈折率分布を表わすグラフ、第３図は本
発明によるグレーデツド形レンズの他の一実施例をイメ
ージファイバに接続した場合の画像伝送路における入射
端部の光線の進行原理を表わす幾何原理図、第４図はこ
のグレーデツド形レンズを構成する四個のグレーデツド
形レンズの径方向屈折率分布を表わすグラフである。
図中の符号で、１は本発明によるグレーデツド形レンズ
、２は単一モード伝送用光ファイバ、４は光線、１１，
１２，１３，１４は従来のグレーデツド形レンズ、１５
は従来のグレーデツド形レンズを組み合わせて構成した
本発明によるグレーデツド形レンズ、１６はイメージフ
ァイバ、１７は入射光線である。FIG. 1 is a geometric principle diagram showing the principle of propagation of light rays at the input end in a communication optical transmission line when an embodiment of the graded lens according to the present invention is connected to a single mode transmission optical fiber; The figure is a graph showing the radial refractive index distribution on both end faces of this graded lens, and FIG. 3 is the incident end of the image transmission path when another embodiment of the graded lens according to the present invention is connected to an image fiber. FIG. 4 is a graph showing the radial refractive index distribution of the four graded lenses constituting this graded lens. In the figure, 1 is a graded lens according to the present invention, 2 is an optical fiber for single mode transmission, 4 is a light beam, 11,
12, 13, 14 are conventional graded lenses, 15
1 is a graded lens according to the present invention constructed by combining conventional graded lenses, 16 is an image fiber, and 17 is an incident light beam.
Claims (1)
次低くなつた一定な径のグレーデツド形レンズにおいて
、その一端面側の屈折率に対して光軸方向と平行な方向
に沿つて他端面側の屈折率ほど低く、しかも前記一端面
側における前記中心と径方向外周側との屈折率差よりも
前記他端面側における前記中心と径方向外周側との屈折
率差の方を大きくしたことを特徴とするグレードデツド
形レンズ。1. In a graded lens with a constant diameter in which the refractive index of the lens gradually decreases toward the outer periphery in the radial direction with respect to the refractive index of the center, the refractive index of one end surface of the lens is parallel to the optical axis direction. The refractive index on the end face side is lower, and the refractive index difference between the center and the radial outer circumferential side on the other end face side is greater than the refractive index difference between the center and the radial outer circumferential side on the one end face side. A graded type lens characterized by:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP55103397A JPS6057048B2 (en) | 1980-07-28 | 1980-07-28 | graded lens |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP55103397A JPS6057048B2 (en) | 1980-07-28 | 1980-07-28 | graded lens |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60118928A Division JPS60258507A (en) | 1985-06-03 | 1985-06-03 | optical transmission line |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5727214A JPS5727214A (en) | 1982-02-13 |
| JPS6057048B2 true JPS6057048B2 (en) | 1985-12-13 |
Family
ID=14352919
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP55103397A Expired JPS6057048B2 (en) | 1980-07-28 | 1980-07-28 | graded lens |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6057048B2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02216111A (en) * | 1989-02-17 | 1990-08-29 | Nec Corp | Semiconductor laser module |
| JP2004046048A (en) * | 2002-07-15 | 2004-02-12 | Moritex Corp | Coupling mechanism between laser diode and single mode fiber |
| JP6112977B2 (en) * | 2013-06-03 | 2017-04-12 | ニスカ株式会社 | Rod lens array and image sensor |
| JP6878770B2 (en) * | 2016-04-05 | 2021-06-02 | 東洋製罐グループホールディングス株式会社 | Optical fiber with lens and optical coupler |
| IL255049B (en) * | 2017-10-16 | 2022-08-01 | Oorym Optics Ltd | Highly efficient compact head-mounted display system |
-
1980
- 1980-07-28 JP JP55103397A patent/JPS6057048B2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5727214A (en) | 1982-02-13 |
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