JP3664847B2

JP3664847B2 - Optical multiplexer / demultiplexer device

Info

Publication number: JP3664847B2
Application number: JP15270497A
Authority: JP
Inventors: 旭熊谷; 徹高橋; 直成笹野; 健一牟田
Original assignee: 昭和電線電纜株式会社
Priority date: 1997-06-10
Filing date: 1997-06-10
Publication date: 2005-06-29
Anticipated expiration: 2017-06-10
Also published as: JPH112732A

Description

【０００１】
【発明の属する技術分野】
本発明は、複数の異なった情報信号を波長分割多重することができる光合分波器装置に関する。
【０００２】
【従来の技術】
従来より、電話やテレビやデータなど多種類の情報信号を伝送させるために、複数の波長を利用して１本の光ファイバにのせる波長分割多重（wavelength div-ision multiplexing , WDM）方式が採用されており、この波長分割多重は光合分波器装置により行われている。
【０００３】
このような光合分波器装置は図８に示すように、１本の光導波路５２および２本の光導波路５３、５４間で２個の波長λ1、λ2の信号を各波長λ1、λ2について遮断、通過させる光合分波器５５で構成されている。このように構成された光合分波器装置５１において、光合分波器５５の入力ポート５５ａに入力ポートパワーＰ11で２個の波長λ1、λ2の光を入力すると、２本の光導波路５３、５４の一方の導波路５３に接続されている光合分波器５５の出力ポート５５ｂ′に出力される波長λ1の信号の出力ポートパワーＰ13、および他方の導波路５４に接続されている光合分波器５５の出力ポート５５ｂに出力される波長λ2の出力ポートパワーＰ14は、
Ｐ13＝Ｐ11＊（１＋ｃｏｓ（Δφ））／２・・・・（１）
Ｐ14＝Ｐ11＊（１−ｃｏｓ（Δφ））／２・・・・（２）
となる。ここで、Δφは波長λ1の光および波長λ２の光のモードの位相差とする。
【０００４】
したがって、波長λ1を１．３１μｍ、波長λ2を１．５５μｍとすると、波長１．５５μｍの出力ポートパワーＰ13、および波長１．３１μｍの出力ポートパワーＰ14と波長との関係は図９に示すように、理論上、サイン波になることがわかる。また、図１０に示すように、波長分離度が例えば−２３ｄＢでは帯域幅は理論上、２１．６ｎｍになる。
【０００５】
【発明が解決しようとする課題】
しかしながら、このような光合分波器装置５１では、波長分離度の帯域幅が狭いという難点があった。
【０００６】
このような難点に対して上述のような光合分波器を２個直列接続させた光合分波器装置が提案されている。例えば図１１（ａ）に示すように、第１の光合分波器６１と第２の光合分波器７１とを直列接続させると、第１の光合分波器６１の入力ポート６１ａに入力する例えば２個の波長１．３１μｍ、１．５５μｍの信号は第１の光合分波器６１で分波され、波長１．５５μｍの信号が第２の光合分波器７１を介して導波路３０に出力される。この光合分波器装置１００によれば、第２の光合分波器７１の出力ポート７１ｂ′の出力ポートパワーＰ２３は図１２に示すように、理論上、波長分離度が−２３ｄＢの場合の帯域幅が８１．６ｎｍになる。
【０００７】
また、図１１（ｂ）に示すように、第１の光合分波器８１と第２の光合分波器９１とを直列接続させると、第１の光合分波器８１の入力ポート８１ａに入力する例えば２個の波長１．３１μｍ、１．５５μｍの信号は第１の光合分波器８１で分波され、波長１．３１μｍの信号が第２の光合分波器９１を介して導波路４０に出力される。この光合分波器装置１００′によれば、第２の光合分波器９１の出力ポート９１ｂ′の出力ポートパワーＰ２４は図１２に示すように、理論上、波長分離度が−２３ｄＢの場合の帯域幅が８１．６ｎｍになる。
【０００８】
しかしながら、このような波長分離度の帯域幅でも光ファイバ通信によっては満足できない場合もある。
【０００９】
本発明はこのような従来の難点を解決するためになされたもので、光ファイバを溶融して一体化した光合分波器を使用して波長分離度の帯域幅を従来より広くすることができる光合分波器装置を提供することを目的としている。
【００１０】
【課題を解決するための手段】
このような目的を達成する本発明の光合分波器装置は、１本の光導波路と少なくとも２本の光導波路との間で少なくとも２個の波長の信号を各波長について遮断、通過させる光合分波器により合波、分波する光合分波器装置において、光合分波器は、少なくとも１つの波長の信号についてそれぞれ異なる遮断中心周波数を有する少なくとも２個の光合分波器で構成され、少なくとも２個の光合分波器の遮断中心周波数は、少なくとも２個の光合分波器のうち一つの光合分波器において少なくとも１つの波長の信号の周波数から所定周波数だけ高い周波数にシフトされ、少なくとも２個の光合分波器のうちの他の光合分波器の一つにおいて少なくとも１つの波長の信号の周波数から所定周波数だけ低い周波数にシフトされて設定されているものである。
【００１１】
このように構成された光合分波器装置は、各光合分波器の遮断中心周波数がそれぞれ異なるので、波長分離度の帯域幅を広くすることができる。
【００１２】
【発明の実施の形態】
以下、本発明の光合分波器装置の実施の一形態について、図面を参照して説明する。
【００１３】
本発明の光合分波器装置は例えば図１に示すように、１本の光導波路２と２本の光導波路３、４との間で例えば２個の波長１．３１μｍ、１．５５μｍの信号を、各波長１．３１μｍ、１．５５μｍについて遮断、通過させる２個の光合分波器５、６により合波、分波するもので、２個の光合分波器５、６が直列接続されている。
【００１４】
２個の光合分波器５、６はそれぞれ４つの入出力用のポートを有している。第１の光合分波器５は、入力ポート５ａ、５ａ′と出力ポート５ｂ、５ｂ′とを有し、出力ポート５ｂに波長１．５５μｍの信号を通過させると共に波長１．３１μｍの信号を遮断させ、出力ポート５ｂ′に波長１．３１μｍの信号を通過させると共に波長１．５５μｍの信号を遮断させるものである。また、波長１．３１μｍの信号について遮断中心周波数を有し、この遮断中心周波数は例えば２０ｎｍだけ高い方向にシフトされて設定されている。第２の光合分波器６は、入力ポート６ａ、６ａ′と出力ポート６ｂ、６ｂ′とを有し、出力ポート６ｂに波長１．３１μｍの信号を通過させると共に波長１．５５μｍの信号を遮断させ、出力ポート６ｂ′に波長１．５５μｍの信号を通過させると共に波長１．３１μｍの信号を遮断させるものである。また、波長１．３１μｍの信号について遮断中心周波数を有し、この遮断中心周波数は例えば２０ｎｍだけ低い方向にシフトされて設定されている。
【００１５】
第１の光合分波器５の入力ポート５ａには１本の光導波路２が接続され、入力ポート５ａ′には何も接続されていない。第１の光合分波器５の出力ポート５ｂには第２の光合分波器６の入力ポート６ａ′が接続され、出力ポート５ｂ′には他方の光導波路４が接続されている。第２の光合分波器６の出力ポート６ｂ′には一方の光導波路３が接続され、入力ポート６ａおよび出力ポート６ｂには何も接続されていない。
【００１６】
このような遮断中心周波数を有する各光合分波器５、６は、図２、図３、図４に示すような波長分離度の帯域幅理論値を具備している。即ち、遮断中心周波数のシフト量が±２０ｎｍの場合、挿入損は０．１４５ｄＢ、波長分離度の帯域は９２ｎｍ、中心波長の分離度は−３５．５ｄＢとなる。
【００１７】
このように構成された本発明の光合分波器装置１において、１本の光導波路２から入力ポートパワーＰ１で２個の波長１．３１μｍ、１．５５μｍの光が入力すると、波長１．５５μｍの信号は第１の光合分波器５で分波されて出力ポート５ｂに出力され、さらに第２の光合分波器６で分波されて出力ポート６ｂ′を介して一方の光導波路３に出力される。この際、第１の光合分波器５の出力ポート５ｂ、および第２の光合分波器６の出力ポート６ｂ′の各出力ポートパワーＰ3は、
Ｐ3＝Ｐ1＊（１＋ｃｏｓ（Δφ））／２・・・・（３）
となる。ここで、Δφは波長１．３１μｍの光および波長１．５５μｍの光のモードの位相差とする。これにより、理論上の波長と損失とは図５に示すようなグラフになる。即ち、図５に示すように、波長分離度が−２３ｄＢでは帯域幅が９１．６ｎｍになるので、従来の光合分波器装置よりも、波長分離度の帯域幅を広くすることができる。
【００１８】
また、波長１．３１μｍの光の波長分離度の帯域幅を広くする場合には、図６に示すように１本の光導波路２と２本の光導波路３、４との間で例えば２個の波長１．３１μｍ、１．５５μｍの信号を、各波長１．３１μｍ、１．５５μｍについて遮断、通過させる２個の光合分波器１５、１６により合波、分波するもので、２個の光合分波器１５、１６が直列接続されている。
【００１９】
２個の光合分波器１５、１６は、上述の光合分波器装置１の各光合分波器５、６と同様に、それぞれ４つの入出力用のポートを有している。第１の光合分波器１５は、入力ポート１５ａ、１５ａ′と出力ポート１５ｂ、１５ｂ′とを有し、出力ポート１５ｂに波長１．５５μｍの信号を通過させると共に波長１．３１μｍの信号を遮断させ、出力ポート１５ｂ′に波長１．３１μｍの信号を通過させると共に波長１．５５μｍの信号を遮断させるものである。また、波長１．５５μｍの信号について遮断中心周波数を有し、この遮断中心周波数は例えば２０ｎｍだけ高い方向にシフトされて設定されている。第２の光合分波器１６は、入力ポート１６ａ、１６ａ′と出力ポート１６ｂ、１６ｂ′とを有し、出力ポート１６ｂに波長１．５５μｍの信号を通過させると共に波長１．３１μｍの信号を遮断させ、出力ポート１６ｂ′に波長１．３１μｍの信号を通過させると共に波長１．５５μｍの信号を遮断させるものである。また、波長１．５５μｍの信号について遮断中心周波数を有し、この遮断中心周波数は例えば２０ｎｍだけ低い方向にシフトされて設定されている。
【００２０】
第１の光合分波器１５の入力ポート１５ａには１本の光導波路２が接続され、入力ポート１５ａ′には何も接続されていない。第１の光合分波器１５の出力ポート１５ｂ′には第２の光合分波器１６の入力ポート１６ａが接続され、出力ポート１５ｂには一方の光導波路３が接続されている。第２の光合分波器１６の出力ポート１６ｂ′には他方の光導波路４が接続され、入力ポート１６ａ′および出力ポート１６ｂには何も接続されていない。
【００２１】
このような遮断中心周波数を有する各光合分波器１５、１６は上述の光合分波器装置１の各光合分波器５、６と同様に、図２、図３、図４に示すような波長分離度の帯域幅理論値を具備している。即ち、遮断中心周波数のシフト量が±２０ｎｍの場合、挿入損は０．１４５ｄＢ、波長分離度の帯域は９２ｎｍ、中心波長の分離度は−３５．５ｄＢとなる。
【００２２】
このように構成された本発明の光合分波器装置１０において、１本の光導波路２から入力ポートパワーＰ１で２個の波長１．３１μｍ、１．５５μｍの光が入力すると、波長１．３１μｍの信号は第１の光合分波器１５で分波されて出力ポート１５ｂ′に出力され、さらに第２の光合分波器１６で分波されて出力ポート１６ｂ′を介して他方の光導波路４に出力される。この際、第１の光合分波器１５の出力ポート１５ｂ′、および第２の光合分波器１６の出力ポート１６ｂ′の各出力ポートパワーＰ４は、
Ｐ４＝Ｐ1＊（１−ｃｏｓ（Δφ））／２・・・・（４）
となる。ここで、Δφは波長１．３１μｍの光および波長１．５５μｍの光のモードの位相差とする。これにより、理論上の波長と損失とは図５に示すようなグラフになる。即ち、図５に示すように、波長分離度が−２３ｄＢでは帯域幅が９１．６ｎｍになるので、従来の光合分波器装置よりも、波長分離度の帯域幅を広くすることができる。
【００２３】
なお、本発明の実施の一形態においては１本の光導波路と、２本の光導波路との間で２個の波長の信号を各波長について遮断、通過させる光合分波器により分波させていたが、これに限らず、１本の光導波路と、２本以上の光導波路との間で２個以上の波長の信号を各波長について遮断、通過させる光合分波器により分波させてもよい。この際、光合分波器は、１つ以上の波長の信号についてそれぞれ異なる遮断中心周波数を有する２個以上の光合分波器で構成させる。また、このような光合分波器装置は、多重化された異なる波長の信号の分波に限らず、複数の波長の信号を合波させることもでき、さらに、複数波の双方向多重に適用させることもできる。
【００２４】
【実施例】
さらに、本発明の光合分波器装置による波長分離度の帯域幅について、実験を行った。なお、本実験においては図１に示す光合分波器装置１を使用して、波長分離度の帯域幅を測定した。測定結果は図７に示すように、波長分離度が−２３ｄＢでは、帯域幅が８９．７ｎｍになることが確認できた。
【００２５】
【発明の効果】
以上、説明したように、本発明の光合分波器装置によれば、少なくとも１つの波長の信号についてそれぞれ異なる遮断中心周波数を有する少なくとも2個の光合分波器で構成したので、波長分離度の帯域幅を従来より広くすることができる。これにより、各波長間の干渉を防ぐことができる。また、誘電体多層膜フィルタや微小光学素子を用いたものに比べて、光学特性が優れ、製造コストも下げることができるので、ＷＤＭ光伝送機器、ＷＤＭ伝送を使用した端末等に利用できる。
【図面の簡単な説明】
【図１】本発明の光合分波器装置の実施の一形態を示す構成図。
【図２】本発明の光合分波器装置の波長分離度の帯域幅の中心波長の変化と挿入損との関係を理論値で示すグラフ。
【図３】本発明の光合分波器装置の波長分離度の帯域幅の中心波長の変化と波長分離度の帯域との関係を理論値で示すグラフ。
【図４】本発明の光合分波器装置の波長分離度の帯域幅の中心波長の変化と中心波長の分離度との関係を理論値で示すグラフ。
【図５】本発明の光合分波器装置の波長分離度の帯域幅の波長と損失との関係を理論値で示すグラフ。
【図６】本発明の光合分波器装置の他の実施の一形態を示す構成図。
【図７】本発明の光合分波器装置の波長分離度の帯域幅の波長と損失との関係を実測値で示すグラフ。
【図８】従来の光合分波器装置を示す構成図。
【図９】従来の光合分波器装置の出力パワーと波長との関係を理論値で示すグラフ。
【図１０】従来の光合分波器装置の波長分離度の帯域幅の波長と損失との関係を理論値で示すグラフ。
【図１１】従来の光合分波器装置を示す図で、（ａ）は波長１．５５μｍの信号を2個の光合分波器に通過させる構成図、（ｂ）は波長１．３１μｍの信号を2個の光合分波器に通過させる構成図。
【図１２】図１１に示す光合分波器装置の波長分離度の帯域幅の波長と損失との関係を理論値で示すグラフ。
【符号の説明】
１、１０・・・・光合分波器装置
２・・・・１本の光導波路
３、４・・・・２本の光導波路
５、６・・・・２個の光合分波器
１５、１６・・・・２個の光合分波器
１．３１μｍ、１．５５μｍ・・・・２個の波長[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical multiplexer / demultiplexer device capable of wavelength division multiplexing a plurality of different information signals.
[0002]
[Prior art]
Conventionally, in order to transmit various types of information signals such as telephones, televisions, and data, a wavelength division-multiplexing (WDM) method that uses a plurality of wavelengths and can be placed on a single optical fiber has been adopted. The wavelength division multiplexing is performed by an optical multiplexer / demultiplexer device.
[0003]
As shown in FIG. 8, such an optical multiplexer / demultiplexer device cuts off signals of two wavelengths λ1 and λ2 between one optical waveguide 52 and two optical waveguides 53 and 54 for each wavelength λ1 and λ2. The optical multiplexer / demultiplexer 55 is made to pass. In the optical multiplexer / demultiplexer device 51 configured as described above, when light of two wavelengths λ1 and λ2 is input to the input port 55a of the optical multiplexer / demultiplexer 55 with the input port power P11, the two optical waveguides 53, 54 are input. The output port power P13 of the signal of wavelength λ1 output to the output port 55b 'of the optical multiplexer / demultiplexer 55 connected to one of the waveguides 53, and the optical multiplexer / demultiplexer connected to the other waveguide 54 The output port power P14 of wavelength λ2 output to the output port 55b of 55 is
P13 = P11 * (1 + cos (Δφ)) / 2 (1)
P14 = P11 * (1-cos (Δφ)) / 2 (2)
It becomes. Here, Δφ is the phase difference between the modes of the light of wavelength λ1 and the light of wavelength λ2.
[0004]
Accordingly, when the wavelength λ1 is 1.31 μm and the wavelength λ2 is 1.55 μm, the relationship between the output port power P13 having a wavelength of 1.55 μm and the output port power P14 having a wavelength of 1.31 μm and the wavelength is as shown in FIG. It turns out that it becomes a sine wave in theory. Further, as shown in FIG. 10, when the wavelength separation is −23 dB, for example, the bandwidth is theoretically 21.6 nm.
[0005]
[Problems to be solved by the invention]
However, such an optical multiplexer / demultiplexer device 51 has a drawback that the bandwidth of wavelength separation is narrow.
[0006]
An optical multiplexer / demultiplexer device in which two optical multiplexers / demultiplexers as described above are connected in series has been proposed for such a difficulty. For example, as shown in FIG. 11A, when a first optical multiplexer / demultiplexer 61 and a second optical multiplexer / demultiplexer 71 are connected in series, they are input to an input port 61a of the first optical multiplexer / demultiplexer 61. For example, two signals having a wavelength of 1.31 μm and 1.55 μm are demultiplexed by the first optical multiplexer / demultiplexer 61, and a signal having a wavelength of 1.55 μm is supplied to the waveguide 30 via the second optical multiplexer / demultiplexer 71. Is output. According to this optical multiplexer / demultiplexer device 100, the output port power P23 of the output port 71b ′ of the second optical multiplexer / demultiplexer 71 is theoretically a band when the wavelength separation is −23 dB as shown in FIG. The width is 81.6 nm.
[0007]
Further, as shown in FIG. 11B, when a first optical multiplexer / demultiplexer 81 and a second optical multiplexer / demultiplexer 91 are connected in series, an input is made to the input port 81a of the first optical multiplexer / demultiplexer 81. For example, two signals having a wavelength of 1.31 μm and 1.55 μm are demultiplexed by the first optical multiplexer / demultiplexer 81, and the signal having a wavelength of 1.31 μm is waveguided via the second optical multiplexer / demultiplexer 91. Is output. According to this optical multiplexer / demultiplexer device 100 ′, the output port power P24 of the output port 91b ′ of the second optical multiplexer / demultiplexer 91 is theoretically the case where the wavelength separation is −23 dB as shown in FIG. The bandwidth is 81.6 nm.
[0008]
However, even such a wavelength separation bandwidth may not be satisfactory depending on the optical fiber communication.
[0009]
The present invention has been made in order to solve such a conventional problem, and it is possible to widen the bandwidth of wavelength separation by using an optical multiplexer / demultiplexer in which an optical fiber is fused and integrated. An object of the present invention is to provide an optical multiplexer / demultiplexer device.
[0010]
[Means for Solving the Problems]
The optical multiplexer / demultiplexer device of the present invention that achieves such an object is an optical multiplexer / demultiplexer that blocks and passes signals of at least two wavelengths for each wavelength between one optical waveguide and at least two optical waveguides. In an optical multiplexer / demultiplexer device that multiplexes and demultiplexes with a wave multiplexer, the optical multiplexer / demultiplexer includes at least two optical multiplexer / demultiplexers each having a different cutoff center frequency for a signal of at least one wavelength, and at least 2 The cutoff center frequency of each optical multiplexer / demultiplexer is shifted from the frequency of the signal of at least one wavelength to a frequency higher by a predetermined frequency in one optical multiplexer / demultiplexer among at least two optical multiplexers / demultiplexers. One of the other optical multiplexers / demultiplexers is set to be shifted from the frequency of the signal of at least one wavelength to a frequency lower by a predetermined frequency in one of the optical multiplexers / demultiplexers A.
[0011]
In the optical multiplexer / demultiplexer device configured as described above, since the cutoff center frequencies of the optical multiplexer / demultiplexers are different from each other, the bandwidth of wavelength separation can be widened.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of an optical multiplexer / demultiplexer device of the present invention will be described with reference to the drawings.
[0013]
For example, as shown in FIG. 1, the optical multiplexer / demultiplexer device according to the present invention has, for example, two signals having a wavelength of 1.31 μm and 1.55 μm between one optical waveguide 2 and two optical waveguides 3 and 4. Are combined and demultiplexed by two optical multiplexers / demultiplexers 5 and 6 that block and pass through each wavelength of 1.31 μm and 1.55 μm, and the two optical multiplexer / demultiplexers 5 and 6 are connected in series. ing.
[0014]
Each of the two optical multiplexers / demultiplexers 5 and 6 has four input / output ports. The first optical multiplexer / demultiplexer 5 has input ports 5a, 5a ′ and output ports 5b, 5b ′, and allows a signal having a wavelength of 1.55 μm to pass through the output port 5b and blocks a signal having a wavelength of 1.31 μm. Thus, a signal having a wavelength of 1.31 μm is allowed to pass through the output port 5b ′ and a signal having a wavelength of 1.55 μm is blocked. Further, a signal having a wavelength of 1.31 μm has a cutoff center frequency, and this cutoff center frequency is set to be shifted in a higher direction by, for example, 20 nm. The second optical multiplexer / demultiplexer 6 has input ports 6a and 6a ′ and output ports 6b and 6b ′, and allows a signal having a wavelength of 1.31 μm to pass through the output port 6b and blocks a signal having a wavelength of 1.55 μm. Thus, a signal having a wavelength of 1.55 μm is allowed to pass through the output port 6b ′ and a signal having a wavelength of 1.31 μm is blocked. Further, a signal having a wavelength of 1.31 μm has a cutoff center frequency, and this cutoff center frequency is set to be shifted in a lower direction by, for example, 20 nm.
[0015]
One optical waveguide 2 is connected to the input port 5a of the first optical multiplexer / demultiplexer 5, and nothing is connected to the input port 5a '. The output port 5b of the first optical multiplexer / demultiplexer 5 is connected to the input port 6a 'of the second optical multiplexer / demultiplexer 6, and the other optical waveguide 4 is connected to the output port 5b'. One optical waveguide 3 is connected to the output port 6b 'of the second optical multiplexer / demultiplexer 6, and nothing is connected to the input port 6a and the output port 6b.
[0016]
Each of the optical multiplexers / demultiplexers 5 and 6 having such a cutoff center frequency has a theoretical bandwidth value of wavelength separation as shown in FIGS. That is, when the amount of shift of the cutoff center frequency is ± 20 nm, the insertion loss is 0.145 dB, the wavelength separation band is 92 nm, and the center wavelength separation is −35.5 dB.
[0017]
In the optical multiplexer / demultiplexer device 1 of the present invention configured as described above, when two light beams having a wavelength of 1.31 μm and 1.55 μm are input from one optical waveguide 2 at the input port power P1, the wavelength is 1.55 μm. The signal is demultiplexed by the first optical multiplexer / demultiplexer 5 and output to the output port 5b, and further demultiplexed by the second optical multiplexer / demultiplexer 6 to the one optical waveguide 3 via the output port 6b '. Is output. At this time, the output port powers P3 of the output port 5b of the first optical multiplexer / demultiplexer 5 and the output port 6b 'of the second optical multiplexer / demultiplexer 6 are:
P3 = P1 * (1 + cos (Δφ)) / 2 (3)
It becomes. Here, Δφ is a phase difference between modes of light having a wavelength of 1.31 μm and light having a wavelength of 1.55 μm. Thereby, the theoretical wavelength and loss become a graph as shown in FIG. That is, as shown in FIG. 5, since the bandwidth becomes 91.6 nm when the wavelength separation is −23 dB, the bandwidth of the wavelength separation can be made wider than that of the conventional optical multiplexer / demultiplexer device.
[0018]
When the bandwidth of the wavelength separation degree of the light having a wavelength of 1.31 μm is widened, for example, two between one optical waveguide 2 and two optical waveguides 3 and 4 as shown in FIG. The signals having the wavelengths of 1.31 μm and 1.55 μm are combined and demultiplexed by the two optical multiplexers / demultiplexers 15 and 16 that block and pass the signals at the wavelengths of 1.31 μm and 1.55 μm. Optical multiplexers / demultiplexers 15 and 16 are connected in series.
[0019]
The two optical multiplexers / demultiplexers 15 and 16 each have four input / output ports, like the optical multiplexer / demultiplexers 5 and 6 of the optical multiplexer / demultiplexer device 1 described above. The first optical multiplexer / demultiplexer 15 has input ports 15a and 15a ′ and output ports 15b and 15b ′, and allows a signal having a wavelength of 1.55 μm to pass through the output port 15b and blocks a signal having a wavelength of 1.31 μm. The signal having the wavelength of 1.31 μm is allowed to pass through the output port 15b ′ and the signal having the wavelength of 1.55 μm is blocked. Further, a signal having a wavelength of 1.55 μm has a cutoff center frequency, and this cutoff center frequency is set to be shifted in a higher direction by, for example, 20 nm. The second optical multiplexer / demultiplexer 16 has input ports 16a and 16a ′ and output ports 16b and 16b ′, and allows a signal having a wavelength of 1.55 μm to pass through the output port 16b and blocks a signal having a wavelength of 1.31 μm. The signal having the wavelength of 1.31 μm is allowed to pass through the output port 16b ′ and the signal having the wavelength of 1.55 μm is blocked. Further, a signal having a wavelength of 1.55 μm has a cutoff center frequency, and this cutoff center frequency is set to be shifted in a lower direction by, for example, 20 nm.
[0020]
One optical waveguide 2 is connected to the input port 15a of the first optical multiplexer / demultiplexer 15, and nothing is connected to the input port 15a '. The input port 16a of the second optical multiplexer / demultiplexer 16 is connected to the output port 15b 'of the first optical multiplexer / demultiplexer 15, and one optical waveguide 3 is connected to the output port 15b. The other optical waveguide 4 is connected to the output port 16b 'of the second optical multiplexer / demultiplexer 16, and nothing is connected to the input port 16a' and the output port 16b.
[0021]
Each of the optical multiplexers / demultiplexers 15 and 16 having such a cutoff center frequency is similar to the optical multiplexer / demultiplexers 5 and 6 of the optical multiplexer / demultiplexer device 1 described above, as shown in FIGS. It has the theoretical bandwidth of wavelength separation. That is, when the amount of shift of the cutoff center frequency is ± 20 nm, the insertion loss is 0.145 dB, the wavelength separation band is 92 nm, and the center wavelength separation is −35.5 dB.
[0022]
In the optical multiplexer / demultiplexer device 10 of the present invention configured as described above, when two light beams having wavelengths of 1.31 μm and 1.55 μm are input from one optical waveguide 2 at the input port power P1, the wavelength is 1.31 μm. Is demultiplexed by the first optical multiplexer / demultiplexer 15 and output to the output port 15b ', and further demultiplexed by the second optical multiplexer / demultiplexer 16 and the other optical waveguide 4 via the output port 16b'. Is output. At this time, the output port powers P4 of the output port 15b 'of the first optical multiplexer / demultiplexer 15 and the output port 16b' of the second optical multiplexer / demultiplexer 16 are:
P4 = P1 * (1-cos (Δφ)) / 2 (4)
It becomes. Here, Δφ is a phase difference between modes of light having a wavelength of 1.31 μm and light having a wavelength of 1.55 μm. Thereby, the theoretical wavelength and loss become a graph as shown in FIG. That is, as shown in FIG. 5, since the bandwidth becomes 91.6 nm when the wavelength separation is −23 dB, the bandwidth of the wavelength separation can be made wider than that of the conventional optical multiplexer / demultiplexer device.
[0023]
In one embodiment of the present invention, a signal having two wavelengths is blocked by one optical waveguide and two optical waveguides by an optical multiplexer / demultiplexer that blocks and passes each wavelength. However, the present invention is not limited to this, and a signal having two or more wavelengths may be demultiplexed between one optical waveguide and two or more optical waveguides by an optical multiplexer / demultiplexer that blocks and passes each wavelength. Good. At this time, the optical multiplexer / demultiplexer is composed of two or more optical multiplexers / demultiplexers having different cutoff center frequencies for signals of one or more wavelengths. In addition, such an optical multiplexer / demultiplexer device is not limited to demultiplexing signals with different wavelengths, but can also multiplex signals with multiple wavelengths, and can be applied to bidirectional multiplexing of multiple waves. It can also be made.
[0024]
【Example】
Furthermore, an experiment was conducted on the bandwidth of wavelength separation by the optical multiplexer / demultiplexer device of the present invention. In this experiment, the bandwidth of wavelength separation was measured using the optical multiplexer / demultiplexer device 1 shown in FIG. As shown in FIG. 7, the measurement result confirmed that the bandwidth was 89.7 nm when the wavelength separation was −23 dB.
[0025]
【The invention's effect】
As described above, according to the optical multiplexer / demultiplexer device of the present invention, at least two optical multiplexer / demultiplexers having different cutoff center frequencies for signals of at least one wavelength are used. The bandwidth can be made wider than before. Thereby, interference between each wavelength can be prevented. In addition, since the optical characteristics are excellent and the manufacturing cost can be reduced as compared with those using a dielectric multilayer filter or a micro optical element, it can be used for WDM optical transmission equipment, terminals using WDM transmission, and the like.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an embodiment of an optical multiplexer / demultiplexer device according to the present invention.
FIG. 2 is a graph showing the relationship between the change in the center wavelength of the wavelength separation bandwidth of the optical multiplexer / demultiplexer device of the present invention and the insertion loss as a theoretical value;
FIG. 3 is a graph showing the relationship between the change in the center wavelength of the bandwidth of wavelength separation and the bandwidth of wavelength separation in the optical multiplexer / demultiplexer device of the present invention as theoretical values.
FIG. 4 is a graph showing the relationship between the change in the center wavelength of the wavelength separation bandwidth of the optical multiplexer / demultiplexer device according to the present invention and the separation between the center wavelengths as a theoretical value;
FIG. 5 is a graph showing the relationship between the wavelength and the loss of the bandwidth of the wavelength separation degree of the optical multiplexer / demultiplexer device of the present invention as a theoretical value.
FIG. 6 is a configuration diagram showing another embodiment of the optical multiplexer / demultiplexer device of the present invention.
FIG. 7 is a graph showing the relationship between the wavelength and the loss of the wavelength separation bandwidth of the optical multiplexer / demultiplexer device according to the present invention as measured values.
FIG. 8 is a configuration diagram showing a conventional optical multiplexer / demultiplexer device.
FIG. 9 is a graph showing the relationship between the output power and wavelength of a conventional optical multiplexer / demultiplexer device as a theoretical value.
FIG. 10 is a graph showing the relationship between the wavelength and the loss of the wavelength separation bandwidth of the conventional optical multiplexer / demultiplexer device as a theoretical value.
11A and 11B are diagrams showing a conventional optical multiplexer / demultiplexer device, where FIG. 11A is a configuration diagram for passing a signal having a wavelength of 1.55 μm through two optical multiplexers / demultiplexers, and FIG. 11B is a signal having a wavelength of 1.31 μm. FIG. 2 is a configuration diagram for passing a signal through two optical multiplexer / demultiplexers.
12 is a graph showing the relationship between the wavelength of the wavelength separation bandwidth and the loss of the optical multiplexer / demultiplexer device shown in FIG. 11 as a theoretical value;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,10 .... Optical multiplexer / demultiplexer apparatus 2 .... One optical waveguide 3, 4, ... Two optical waveguides 5, 6, ... Two optical multiplexer / demultiplexers 15, 16 ··· 2 optical multiplexers / demultiplexers 1.31 µm, 1.55 µm ··· 2 wavelengths

Claims

１本の光導波路と少なくとも２本の光導波路との間で少なくとも２個の波長の信号を各波長について遮断、通過させる光合分波器により合波、分波する光合分波器装置において、
前記光合分波器は、少なくとも１つの波長の信号についてそれぞれ異なる遮断中心周波数を有する少なくとも２個の光合分波器で構成され、
前記少なくとも２個の光合分波器の遮断中心周波数は、前記少なくとも２個の光合分波器のうち一つの光合分波器において少なくとも１つの波長の信号の周波数から所定周波数だけ高い周波数にシフトされ、前記少なくとも２個の光合分波器のうちの他の光合分波器の一つにおいて前記少なくとも１つの波長の信号の周波数から所定周波数だけ低い周波数にシフトされて設定されていることを特徴とする光合分波器装置。In an optical multiplexer / demultiplexer device that multiplexes and demultiplexes signals of at least two wavelengths between one optical waveguide and at least two optical waveguides with respect to each wavelength by an optical multiplexer / demultiplexer that passes the signals.
The optical multiplexer / demultiplexer includes at least two optical multiplexers / demultiplexers each having a different cutoff center frequency for a signal of at least one wavelength,
Cutoff center frequency of said at least two optical coupler, said shifted from at least one frequency of the wavelength of the signal to a higher frequency by a predetermined frequency in one of the optical coupler of the at least two optical multiplexer In one of the at least two optical multiplexers / demultiplexers, the frequency is set to be shifted to a frequency lower by a predetermined frequency from the frequency of the signal of the at least one wavelength. Optical multiplexer / demultiplexer device.