JP3701457B2 - Optical amplitude phase characteristic measuring apparatus and measuring method thereof - Google Patents

Optical amplitude phase characteristic measuring apparatus and measuring method thereof Download PDF

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JP3701457B2
JP3701457B2 JP00891998A JP891998A JP3701457B2 JP 3701457 B2 JP3701457 B2 JP 3701457B2 JP 00891998 A JP00891998 A JP 00891998A JP 891998 A JP891998 A JP 891998A JP 3701457 B2 JP3701457 B2 JP 3701457B2
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optical
frequency component
output
fundamental wave
difference
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JPH11211572A (en
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進 町田
軍 陳
喜久 山本
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Japan Science and Technology Agency
Nippon Telegraph and Telephone Corp
National Institute of Japan Science and Technology Agency
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Japan Science and Technology Agency
Nippon Telegraph and Telephone Corp
National Institute of Japan Science and Technology Agency
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Priority to EP98118233A priority patent/EP0908710B1/en
Priority to US09/160,910 priority patent/US6141138A/en
Priority to EP04013967A priority patent/EP1455170B1/en
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Description

【０００１】
【発明の属する技術分野】
本発明は、光の振幅と位相を測定する光振幅位相特性測定装置およびその測定方法に関するものである。
【０００２】
【従来の技術】
従来、非線形光学結晶等の評価には、二つの波長の異なる光源を用いて、その和もしくは差の周波数の光を測定する。この時、和もしくは差周波の波長は光源のどちらかの波長の第２高調波の波長に近接しており、和もしくは差周波成分と第２高調波成分および光源の基本波成分の分離回路に問題がある。もし、この分離回路から和もしくは差周波成分以外の成分が漏れると背景光になり、分離を完全にするには大きな損失を伴い、共に測定感度を劣化させる原因になる。
【０００３】
一方、光の振幅と位相を高感度に測定する方法としては、ホモダイン検波法またはヘテロダイン検波法が用いられている。このホモダイン検波法またはヘテロダイン検波法では、局発光との干渉効果を用いるために背景光の影響を除去することができる。しかしこれらの方法は、基本的に干渉計を構成しているために、干渉計を安定化しなければならない。この干渉計の安定化は干渉計の位相変動を安定にするために、被測定信号の振幅と位相変化は、干渉計の位相変動を分離しなければ、高感度な振幅及び位相特性の測定は困難である。
【０００４】
【発明が解決しようとする課題】
上記したように、上記した従来の方法では、ホモダイン検波法またはヘテロダイン検波法による光の振幅と位相の高感度測定では、干渉計を安定化する必要があるために、測定方法に問題がある。
本発明は、上記問題を除去し、干渉計を安定化することなく、高感度、かつ、高安定な光の振幅と位相の測定を行うことができる光振幅位相特性測定装置およびその測定方法を提供することを目的とする。
【０００５】
【課題を解決するための手段】
本発明は、上記目的を達成するために、
〔１〕光振幅位相特性測定装置において、二つの波長の異なる光源と、前記二つの光源の出力光の基本波成分を分岐する光分岐器と、この光分岐器出力のどちらか一方の光路に配置される被測定試料と、前記光分岐器の出力の他方の光路に前記二つの光源の基本波の和周波成分を発生させる手段と、前記光分岐器の出力のどちらか一方の光路差を変調する手段と、前記二つの基本波成分と前記被測定試料で発生した和周波成分を合波する光合波器と、この光合波器の出力光を二つの基本波成分と和周波成分に分波する光分波器と、この光分波器出力の二つの基本波成分をそれぞれ検波する二つの光検波手段と、この光検波手段の出力の二つの交流信号の和の周波数成分を発生させる手段と、前記光分波器の出力の和周波成分を検波する手段と、この和周波成分の出力交流信号の振幅と位相差を検出する手段とを設けるようにしたものである。
【０００６】
〔２〕光振幅位相測定方法において、二つの波長の異なる光源と、前記二つの光源の出力光の基本波成分を分岐する光分岐器と、この光分岐器の出力のどちらか一方の光路に配置される被測定試料と、前記光分岐器の出力の他方の光路に前記二つの光源の基本波の和周波成分を発生させる手段と、前記光分岐器の出力のどちらか一方の光路差を変調する手段と、前記二つの基本波成分と前記被測定試料で発生した和周波成分を合波する光合波器と、この光合波器の出力光を二つの基本波成分と和周波成分に分波する光分波器と、この光分波器の出力の二つの基本波成分をそれぞれ検波する二つの光検波手段と、この光検波手段の出力の二つの交流信号の和周波数成分を発生させる手段と、前記光分波器出力の和周波成分を検波する手段と、この和周波成分の出力交流信号の振幅と位相差を検出する手段とを配置し、
前記二つの光源の出力光の基本波成分を、前記光分岐器で分岐後、どちらか一方の光路差を変調して、前記二つの基本波成分と和周波成分をそれぞれ別々にホモダイン検波を行い、光路差の変調によって発生する二つの基本波成分による交流信号の和の周波数の交流信号を基準信号として、前記被測定試料で発生する光の和周波成分の振幅と位相差を測定するようにしたものである。
【０００７】
〔３〕光振幅位相特性測定装置において、二つの波長の異なる光源と、前記二つの光源の出力光の基本波成分を分岐する光分岐器と、この光分岐器の出力のどちらか一方の光路に配置される被測定試料と、前記光分岐器の出力の他方の光路に前記二つの光源の基本波の差周波成分を発生させる手段と、前記光分岐器の出力のどちらか一方の光路差を変調する手段と、前記二つの基本波成分と前記被測定試料で発生した差周波成分を合波する光合波器と、この光合波器の出力光を二つの基本波成分と差周波成分に分波する光分波器と、この光分波器の出力の二つの基本波成分をそれぞれ検波する二つの光検波手段と、この光検波手段の出力の二つの交流信号の差周波数成分を発生させる手段と、前記光分波器の出力の差周波成分を検波する手段と、この差周波成分の出力交流信号の振幅と位相差を検出する手段とを設けるようにしたものである。
【０００８】
〔４〕光振幅位相特性測定方法において、二つの波長の異なる光源と、前記二つの光源の出力光の基本波成分を分岐する光分岐器と、この光分岐器の出力のどちらか一方の光路に配置される被測定試料と、前記光分岐器の出力の他方の光路に前記二つの光源の基本波の差周波成分を発生させる手段と、前記光分岐器の出力のどちらか一方の光路差を変調する手段と、前記二つの基本波成分と前記被測定試料で発生した差周波成分を合波する光合波器と、この光合波器の出力光を二つの基本波成分と差周波成分に分波する光分波器と、この光分波器の出力の二つの基本波成分をそれぞれ検波する二つの光検波手段と、この光検波手段の出力の二つの交流信号の差周波数成分を発生させる手段と、前記光分波器の出力の差周波成分を検波する手段と、この差周波成分の出力交流信号の振幅と位相差を検出する手段とを配置し、
前記二つの光源の出力光の基本波成分を、前記光分岐器で分岐後、どちらか一方の光路差を変調して、前記二つの基本波成分と差周波成分をそれぞれ別々にホモダイン検波を行い、光路差の変調によって発生する二つの基本波成分による交流信号の差の周波数の交流信号を基準信号として、前記被測定試料で発生する光の差周波成分の振幅と位相差を測定するようにしたものである。
【０００９】
〔５〕光振幅位相特性測定装置において、二つの波長の異なる光源と、前記二つの光源の出力光の基本波成分を合波する光合波器と、この光合波器の出力の光路に配置され、和周波成分を発生させる被測定試料と、二つの基本波成分と和周波成分を同時に分岐する光分岐器と、この光分岐器の出力のどちらか一方の光路差を変調する手段と、前記二つの基本波成分と前記被測定試料で発生した和周波成分を合波する光合波器と、この光合波器の出力光を二つの基本波成分と和周波成分に分波する光分波器と、この光分波器の出力の二つの基本波成分をそれぞれ検波する二つの光検波手段と、この光検波手段の出力の二つの交流信号の和周波数成分を発生させる手段と、前記光分波器の出力の和周波成分を検波する手段と、この和周波成分の出力交流信号の振幅と位相差を検出する手段とを設けるようにしたものである。
【００１０】
〔６〕光振幅位相特性測定方法において、二つの波長の異なる光源と、前記二つの光源の出力光の基本波成分を合波する光合波器と、この光合波器の出力の光路に配置され、和周波成分を発生させる被測定試料と、二つの基本波成分と和周波成分を同時に分岐する光分岐器と、この光分岐器の出力のどちらか一方の光路差を変調する手段と、前記二つの基本波成分と前記被測定試料で発生した和周波成分を合波する光合波器と、この光合波器の出力光を二つの基本波成分と和周波成分に分波する光分波器と、この光分波器の出力の二つの基本波成分をそれぞれ検波する二つの光検波手段と、この光検波手段の出力の二つの交流信号の和周波数成分を発生させる手段と、前記光分波器の出力の和周波成分を検波する手段と、この和周波成分の出力交流信号の振幅と位相差を検出する手段とを配置し、
前記二つの光源の出力光の基本波成分を、前記光合波器で合波後、前記出力光の基本波成分と被測定試料で発生する和周波成分とを分岐し、どちらか一方の光路差を変調して、前記二つの基本波成分と和周波成分をそれぞれ別々にホモダイン検波を行い、光路差の変調によって発生する二つの基本波成分による交流信号の和の周波数の交流信号を基準信号として、前記被測定試料で発生する光の和周波成分の振幅と位相差を測定するようにしたものである。
【００１１】
〔７〕光振幅位相特性測定装置において、二つの波長の異なる光源と、前記二つの光源の出力光の基本波成分を合波する光合波器と、この光合波器の出力の光路に配置され、差周波成分を発生させる被測定試料と、二つの基本波成分と差周波成分を同時に分岐する光分岐器と、この光分岐器の出力のどちらか一方の光路差を変調する手段と、前記二つの基本波成分と前記被測定試料で発生した差周波成分を合波する光合波器と、この光合波器の出力光を二つの基本波成分と差周波成分に分波する光分波器と、この光分波器の出力の二つの基本波成分をそれぞれ検波する二つの光検波手段と、この光検波手段の出力の二つの交流信号の差周波数成分を発生させる手段と、前記光分波器の出力の差周波成分を検波する手段と、この差周波成分の出力交流信号の振幅と位相差を検出する手段とを設けるようにしたものである。
【００１２】
〔８〕光振幅位相特性測定方法において、二つの波長の異なる光源と、前記二つの光源の出力光の基本波成分を合波する光合波器と、この光合波器の出力の光路に配置され、差周波成分を発生させる被測定試料と、二つの基本波成分と差周波成分を同時に分岐する光分岐器と、この光分岐器の出力のどちらか一方の光路差を変調する手段と、前記二つの基本波成分と前記被測定試料で発生した差周波成分を合波する光合波器と、この光合波器の出力光を二つの基本波成分と差周波成分に分波する光分波器と、この光分波器の出力の二つの基本波成分をそれぞれ検波する二つの光検波手段と、この光検波手段の出力の二つの交流信号の差周波数成分を発生させる手段と、前記光分波器の出力の差周波成分を検波する手段と、この差周波成分の出力交流信号の振幅と位相差を検出する手段とを配置し、
前記二つの光源の出力光の基本波成分を、前記光合波器で合波後、前記出力光の基本波成分と被測定試料で発生する差周波成分とを分岐し、どちらか一方の光路差を変調して、前記二つの基本波成分と差周波成分をそれぞれ別々にホモダイン検波を行い、光路差の変調によって発生する二つの基本波成分による交流信号の差の周波数の交流信号を基準信号として、前記被測定試料で発生する光の差周波成分の振幅と位相差を測定するようにしたものである。
【００１３】
【発明の実施の形態】
以下、本発明の実施の形態について図面を参照して詳細に説明する。
まず、本発明の第１実施例について説明する。
図１は本発明の第１実施例を示す光位相特性測定装置の構成図である。
この図に示すように、この実施例の光振幅位相測定装置は、第１の光源１、第２の光源２、光分岐器３、和周波発生素子４、ミラー５、被測定試料６、光路差変調用信号発生器７、光路差変調用ミラー８、光合波器９、第１の光分波器１０，第２の光分波器１１、第３の光分波器１２、第４の光分波器１３、第１の光検波器１４、第２の光検波器１５、第３の光検波器１６、第４の光検波器１７、第５の光検波器１８、第６の光検波器１９、第１の差動増幅器２０、第２の差動増幅器２１、第３の差動増幅器２２、変調器２３、同期検出器２４により構成される。
【００１４】
ここで、光分岐器３は二つの基本波成分を同時に分岐するものであり、光合波器９は基本波成分と、和周波成分を同時に合波するものであり、ハーフミラー、無偏光ビームスプリッタ、偏光ビームスプリッタ、光方向性結合器などが使用可能である。
また、和周波発生素子４は、二つの光源の基本波から和周波成分を発生させる手段に、光路差変調用信号発生器７、光路差変調用ミラー８は光路差を変調する手段に、光分波器１０，１１，１２，１３は基本波成分と和周波成分を分波する手段に、光検波器１４，１５と差動増幅器２０および光検波器１６，１７と差動増幅器２１は基本波成分を検波する手段に、光検波器１８，１９と差動増幅器２２は和周波成分を検波手段に、変調器２３は交流信号の和の周波数成分を発生させる手段に、同期検出器２４は振幅と位相差を検出する手段にそれぞれ対応する。
【００１５】
なお、和周波発生素子４は局発光側の和周波成分を効率良く発生させるために、非線形光学結晶を用いる。
また、光路差変調用ミラー８は光波長の数倍程度の振動が得られれば十分であり、ピエゾ素子に光学ミラーを張り付けたものが使用可能である。さらに、この作用は、光の位相を連続的に変化させるものであり、同等の位相変化が得られるものならばどのようなものでも良い。
【００１６】
更に、光分波器１０，１１，１２，１３は基本波成分と和周波成分とを分波するものであり、分光プリズム、ダイクロイックミラーなどが使用可能である。また、光分波器１０，１３を一体化して基本波成分と和周波成分を同時に分波する分波器の構成も使用することができる。
また、光分波器１２，１３の出力を光検波器として、１個の光検波器を用いる方法もあるが、この実施例に示すように、２個の光検波器１４，１５と差動増幅器２０、および２個の光検波器１６，１７と差動増幅器２１、さらに２個の光検波器１８，１９と差動増幅器２２の組み合わせによるバランスド検波の構成の方が、光源の出力光の持つ振幅雑音が抑圧され、測定系の雑音がショット雑音レベルになるので、ＳＮ比が、改善されて高感度になることは明らかである。
【００１７】
また、同期検出器２４としてはロックイン増幅器等を使用することができる。
以下、本発明の第１実施例による光位相特性測定装置の動作について説明する。
ホモダイン干渉計の不安定性の原因は、干渉計の光路差の変動による位相変化である。一般的に、この位相変化を検出して、負帰還制御によって干渉計を安定化しているために、測定のための位相信号と負帰還制御信号を分離することは困難である。
【００１８】
いま、干渉計を安定化させずに、一方の光路差を変調すると、その変調速度と振幅にしたがって干渉縞が変化し、交流信号が発生する。この交流信号の振幅は干渉計の可視度に一致しているために、非常に安定である（参考文献：特願平８─１８５２３５号）。しかし、干渉計が安定化されていないために生じる不安定性は、この交流信号の位相に変換されるので、このままでは、安定に振幅と位相の特性を測定することはできない。
【００１９】
そこで、光源の出力光によって発生させた２次高調波（周波数が２倍、波長が１／２）を用いると、非常に安定に位相特性を測定することができる。（参考文献：特願平９─２６２０６４号）
いま、二つの光源の光の周波数をｆo1とｆo2とすると、この和の光の周波数ｆosは、ｆos＝ｆo1＋ｆo2になる。ここで、干渉計の光路差の変調波形を３角波で行うと、検波出力には光路差の変調速度に応じた交流信号が発生する。二つの光源とその和周波の光に対する検波出力の交流信号の周波数をそれぞれｆr1，ｆr2，ｆrsとすると、ｆr1＝ｆo1／ｋ、ｆr2＝ｆo2／ｋ、ｆrs＝ｆos／ｋの関係になる（ｋは光路差の変調速度に関係する定数）。したがって、和周波成分の検波出力の周波数ｆrsはｆr1とｆr2の和の周波数になる。
【００２０】
ここで、ｆr1とｆr2の交流信号から合成した和の周波数ｆrr（ｆrr＝ｆr1＋ｆr2）成分の交流信号は光の周波数ｆo1とｆo2の位相情報を保存しているために、その和の周波数ｆrrの交流信号成分もｆo1とｆo2の位相情報を保存する。
したがって、和の周波数ｆrrの交流信号成分を基準信号として、和周波の光を検波した交流信号成分ｆrsを同期検出すれば、和周波の光の振幅と位相を高感度で測定することができる。
【００２１】
この干渉計はホモダイン検波方式であるため、一方の光路を局部発振光として十分な光量を用いれば、他方の光路の信号光の強度を非常に小さくすることが可能で、高感度な位相特性の測定と同時に振幅特性も測定可能である。さらに、ここで用いる光検波器は、光路差を変調したときに発生する交流信号を検波するのに必要な帯域幅で十分であり、広帯域特性を必要としない。
【００２２】
図１において、いま、第１の光源１および第２の光源２の出力光を光分岐器３で分岐し、一方は、和周波発生素子４で和周波成分を発生させ、二つの基本波成分と和周波成分をホモダイン検波の局部発振光とする。この時、和周波発生素子４の出力の基本波成分と和周波成分をミラー５で反射させ、全ての成分を光合波器９に導く。
【００２３】
また、光分岐器３で分岐されたもう一方は、信号光として被測定用試料６に入射し、被測定用試料６で発生した和周波成分と基本波成分は、光路差変調用信号発生器７で作動する光路差変調用ミラー８で反射させ、全ての成分を光合波器９に導く。
光合波器９で合波された三組の成分は、第１の光分波器１０と第２の光分波器１１でそれぞれ基本波成分と和周波成分に分波する。
【００２４】
第１の光分波器１０と第２の光分波器１１で分波された基本波の成分は、それぞれ第３の光分波器１２と第４の光分波器１３でさらに二つの基本波成分に分波し、第１の光検波器１４，第２の光検波器１５と第１の差動増幅器２０および第３の光検波器１６，第４の光検波器１７と第２の差動増幅器２１で検波し増幅する。第１の差動増幅器２０、第２の差動増幅器２１の出力信号のうち光路差の変調によって生じた交流信号成分を変調器２３に導く。この変調器２３で、基本波による二つの交流信号成分の和の周波数を発生させ、同期検出器２４の基準信号入力端子に接続する。
【００２５】
一方、第１の光分波器１０と第２の光分波器１１で分波した和周波成分は、第５の光検波器１８，第６の光検波器１９と第３の差動増幅器２２で検波、増幅して、同期検出器２４の信号入力端子に接続する。
また、変調器２３で発生させた同期検出器２４の基準信号の周波数と和周波成分を検波した信号光成分の周波数は、干渉計が変動しても、常に等しいために、同期検出器２４では高感度に信号光成分を測定することができる。
【００２６】
次に、第１実施例を用いて、被測定試料で発生する和周波成分の振幅と位相差を測定する方法について述べる。
（１）二つの光源１，２の出力光を同時に分波する。
（２）光分岐器３の分岐比を調整して、必要かつ十分な局発光側の光量を設定する。
【００２７】
（３）局発光側に挿入した和周波発生素子４としての非線形光学結晶４で和周波の光を発生させ、二つの基本波と同時に光合波器９に導く。
（４）信号光側に設置した非測定試料６からの和周波の透過光、反射光または発光光と二つの基本波成分は、光路差変調用信号発生器７の３角波で動作する光路差変調用ミラー８で同時に変調して、光合波器９で局発光成分と合波する。
（５）光合波器９のそれぞれの出力光を第１の光分波器１０，第２の光分波器１１で基本波成分と和周波成分とに分波し、さらに、基本波成分は第３の光分波器１２，第４の光分波器１３でそれぞれの基本波に分波する。
【００２８】
（６）第１〜第４の光分波器１０，１１，１２，１３で分波されたそれぞれの成分を検波、増幅して三つの交流信号成分を出力する。
（７）このうち基本波による二つの交流信号は、変調器２３でその和の成分を発生させ、同期検出器２４の基準信号入力端子に接続する。
（８）和周波による交流信号は同期検出器２４の信号入力端子に接続して、和周波成分の振幅と基準信号との位相差を求める。
【００２９】
本発明の第２実施例について説明する。
図２は本発明の第２実施例を示す光位相特性測定装置の構成図である。なお、第１実施例と同様の部分は同じ符号を付してそれらの説明は省略する。
この図に示すように、この実施例の光振幅位相測定装置は、光合波器２５と光分岐器３１を備える点が第１実施例のものと相違し、その他は第１実施例と略同じ構成である。
【００３０】
ここで、光合波器２５は第１の光源１と第２の光源２からの二つの基本波成分を合波するものであり、光分岐器３１は二つの基本波成分と和周波成分を同時に分岐するものであり、ハーフミラー、無偏光ビームスプリッタ、偏光ビームスプリッタ、光方向性結合器などが使用可能である。
以下、この実施例の光振幅位相測定装置の動作について説明する。
【００３１】
図２において、いま、第１の光源１及び第２の光源２の出力光を光合波器２５で合波し、その出力を被測定試料６に入射して和周波成分を発生させる。二つの基本波成分と和周波成分は、光分岐器３１で同時に分岐し、ホモダイン検波の信号光と局部発振光として、第１実施例と同様に二つの基本波成分と和周波成分を光検波して、和周波成分の振幅と位相を測定する。
【００３２】
なお、第１及び第２実施例では和周波発生素子を用いたが、これを差周波発生素子とし、変調器の出力を二つの基本波の交流信号成分の差周波にすれば、非測定試料で発生する差周波成分の振幅と位相差を測定することができる。
すなわち、差の光の周波数をｆod、差周波成分を検波した信号の周波数をｆrdとすると、ｆrd＝（ｆo1−ｆ02）／ｋ＝ｆr1−ｆr2であるから、前述の和周波と同様に、変調器によって発生させた二つの基本波成分の差の周波数成分を基準信号として、光の差周波成分の検波信号を同期検出することができる。
【００３３】
さらに、第１、第２実施例ではマッハツェンダー形干渉計での構成を示したが、マイケルソン形干渉計などの構成でも同様の動作を行わせることができる。さらに、構成部品も光ファイバを用いた部品の使用も可能である。
なお、本発明は上記実施例に限定されるものではなく、本発明の趣旨に基づいて種々の変形が可能であり、これらを本発明の範囲から排除するものではない。
【００３４】
【発明の効果】
以上、詳細に説明したように、本発明によれば、以下のような効果を奏することができる。
（Ａ）光源の二つの基本波と、それらと位相相関を持った和もしくは差の周波数の光に対して、光路差を変調して発生する交流信号成分を測定するために、干渉計を安定化する必要もなく、非常に安定である。
【００３５】
（Ｂ）さらに、ホモダイン検波法と位相同期検出器を用いるために、非常に高感度であり、振幅特性と位相特性を同時に測定することが可能である。
（Ｃ）また、光検波器の周波数特性に広帯域特性を必要とせず、構成も簡単である。
【図面の簡単な説明】
【図１】本発明の第１実施例を示す光位相特性測定装置の構成図である。
【図２】本発明の第２実施例を示す光位相特性測定装置の構成図である。
【符号の説明】
１ 第１の光源
２ 第２の光源
３，３１ 光分岐器
４ 和周波発生素子（非線形光学素子）
５ ミラー
６ 被測定試料
７ 光路差変調用信号発生器
８ 光路差変調用ミラー
９，２５ 光合波器
１０，１１，１２，１３ 光分波器（第１〜第４の光分波器）
１４，１５，１６，１７，１８，１９ 光検波器（第１〜第６の光検波器）
２０，２１，２２ 差動増幅器（第１〜第３の差動増幅器）
２３ 変調器
２４ 同期検出器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical amplitude and phase characteristic measuring apparatus for measuring the amplitude and phase of light and a measuring method thereof.
[0002]
[Prior art]
Conventionally, for evaluation of a nonlinear optical crystal or the like, light having a frequency of the sum or difference is measured using two light sources having different wavelengths. At this time, the wavelength of the sum or difference frequency is close to the wavelength of the second harmonic of either wavelength of the light source, and the separation circuit for the sum or difference frequency component and the second harmonic component and the fundamental wave component of the light source is used. There's a problem. If a component other than the sum or difference frequency components leaks from this separation circuit, it becomes background light, which causes a large loss for complete separation, and causes a deterioration in measurement sensitivity.
[0003]
On the other hand, homodyne detection or heterodyne detection is used as a method for measuring the amplitude and phase of light with high sensitivity. In this homodyne detection method or heterodyne detection method, the influence of background light can be removed because the interference effect with local light is used. However, since these methods basically constitute an interferometer, the interferometer must be stabilized. Since the stabilization of the interferometer stabilizes the phase fluctuation of the interferometer, the amplitude and phase change of the signal under measurement must be separated from the phase fluctuation of the interferometer. Have difficulty.
[0004]
[Problems to be solved by the invention]
As described above, the above-described conventional method has a problem in the measurement method because it is necessary to stabilize the interferometer in the high sensitivity measurement of the amplitude and phase of light by the homodyne detection method or the heterodyne detection method.
The present invention eliminates the above problems and provides an optical amplitude and phase characteristic measuring apparatus and a measuring method thereof capable of measuring highly sensitive and highly stable light amplitude and phase without stabilizing the interferometer. The purpose is to provide.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides
[1] In the optical amplitude phase characteristic measuring apparatus, two light sources having different wavelengths, an optical branching device for branching the fundamental wave component of the output light of the two light sources, and one of the optical paths of the optical branching device output A sample to be measured, means for generating a sum frequency component of the fundamental wave of the two light sources in the other optical path of the output of the optical splitter, and an optical path difference of one of the outputs of the optical splitter. Means for modulating; an optical multiplexer for combining the two fundamental wave components and the sum frequency component generated by the sample to be measured; and the output light of the optical multiplexer is divided into two fundamental wave components and a sum frequency component. An optical demultiplexer for wave generation, two optical detection means for detecting two fundamental wave components of the output of the optical demultiplexer, and a frequency component of the sum of the two AC signals of the output of the optical detection means Means for detecting the sum frequency component of the output of the optical demultiplexer; It is obtained so as to provide a means for detecting the amplitude and phase difference of the output AC signal of the sum frequency component.
[0006]
[2] In the optical amplitude phase measurement method, two light sources having different wavelengths, an optical branching device for branching the fundamental wave component of the output light of the two light sources, and one of the optical paths of the outputs of the optical branching device A sample to be measured, means for generating a sum frequency component of the fundamental wave of the two light sources in the other optical path of the output of the optical splitter, and an optical path difference of one of the outputs of the optical splitter. Means for modulating; an optical multiplexer for combining the two fundamental wave components and the sum frequency component generated by the sample to be measured; and the output light of the optical multiplexer is divided into two fundamental wave components and a sum frequency component. An optical demultiplexer for wave generation, two optical detection means for detecting two fundamental wave components of the output of the optical demultiplexer, and a sum frequency component of two AC signals of the output of the optical detection means Means for detecting the sum frequency component of the output of the optical demultiplexer, and And means for detecting the amplitude and the phase difference between the output AC signal of the sum frequency component arranged,
After the fundamental wave components of the output light of the two light sources are branched by the optical splitter, the optical path difference of either one is modulated, and the two fundamental wave components and the sum frequency component are separately subjected to homodyne detection. The amplitude and phase difference of the sum frequency component of the light generated in the measured sample are measured using the AC signal having the frequency of the sum of the AC signals of the two fundamental wave components generated by the modulation of the optical path difference as a reference signal. It is a thing.
[0007]
[3] In the optical amplitude and phase characteristic measuring device, two light sources having different wavelengths, an optical branching device for branching the fundamental wave component of the output light of the two light sources, and an optical path of one of the outputs of the optical branching device A sample to be measured, means for generating a difference frequency component of a fundamental wave of the two light sources in the other optical path of the output of the optical splitter, and an optical path difference of one of the outputs of the optical splitter Means for modulating the two fundamental wave components and the difference frequency component generated by the sample to be measured, and the output light of the optical multiplexer into two fundamental wave components and a difference frequency component. Generates an optical demultiplexer for demultiplexing, two optical detection means for detecting the two fundamental wave components of the output of the optical demultiplexer, and a difference frequency component of the two AC signals of the output of the optical detection means Means for detecting the difference frequency component of the output of the optical demultiplexer It is obtained by so providing a means for detecting the amplitude and phase difference of the output AC signal of the difference frequency component.
[0008]
[4] In the optical amplitude phase characteristic measurement method, two light sources having different wavelengths, an optical branching device for branching a fundamental wave component of output light from the two light sources, and an optical path of one of the outputs of the optical branching device A sample to be measured, means for generating a difference frequency component of a fundamental wave of the two light sources in the other optical path of the output of the optical splitter, and an optical path difference of one of the outputs of the optical splitter Means for modulating the two fundamental wave components and the difference frequency component generated by the sample to be measured, and the output light of the optical multiplexer into two fundamental wave components and a difference frequency component. Generates an optical demultiplexer for demultiplexing, two optical detection means for detecting the two fundamental wave components of the output of the optical demultiplexer, and a difference frequency component of the two AC signals of the output of the optical detection means Means for detecting the difference frequency component of the output of the optical demultiplexer , Place and means for detecting the amplitude and the phase difference between the output AC signal of the difference frequency component,
After the fundamental wave component of the output light of the two light sources is branched by the optical splitter, the optical path difference of either one is modulated, and the two fundamental wave components and the difference frequency component are separately subjected to homodyne detection. The amplitude and phase difference of the difference frequency component of the light generated in the measured sample are measured using an AC signal having a frequency of the difference between the AC signals of the two fundamental wave components generated by the modulation of the optical path difference as a reference signal. It is a thing.
[0009]
[5] In the optical amplitude and phase characteristic measuring device, two light sources having different wavelengths, an optical multiplexer for combining the fundamental wave components of the output light of the two light sources, and an optical path of the output of the optical multiplexer are arranged. A sample to be measured for generating a sum frequency component, an optical branching device for branching two fundamental wave components and a sum frequency component simultaneously, means for modulating the optical path difference of one of the outputs of the optical branching device, An optical multiplexer that combines two fundamental wave components and the sum frequency component generated by the sample to be measured, and an optical demultiplexer that demultiplexes the output light of the optical multiplexer into two fundamental wave components and a sum frequency component Two optical detection means for detecting the two fundamental wave components of the output of the optical demultiplexer, means for generating the sum frequency component of the two AC signals of the output of the optical detection means, Means for detecting the sum frequency component of the output of the wave generator and the output of this sum frequency component It is obtained so as to provide a means for detecting the amplitude and phase difference of the AC signal.
[0010]
[6] In the method of measuring optical amplitude and phase characteristics, two light sources having different wavelengths, an optical multiplexer for combining the fundamental wave components of the output light of the two light sources, and an optical path of the output of the optical multiplexer are arranged. A sample to be measured for generating a sum frequency component, an optical branching device for branching two fundamental wave components and a sum frequency component simultaneously, means for modulating the optical path difference of one of the outputs of the optical branching device, An optical multiplexer that combines two fundamental wave components and the sum frequency component generated by the sample to be measured, and an optical demultiplexer that demultiplexes the output light of the optical multiplexer into two fundamental wave components and a sum frequency component Two optical detection means for detecting the two fundamental wave components of the output of the optical demultiplexer, means for generating the sum frequency component of the two AC signals of the output of the optical detection means, Means for detecting the sum frequency component of the output of the wave generator and the output of this sum frequency component And means for detecting the amplitude and phase difference of the AC signal is disposed,
After the fundamental wave components of the output light of the two light sources are combined by the optical multiplexer, the fundamental wave component of the output light and the sum frequency component generated in the sample to be measured are branched, and either one of the optical path differences The two fundamental wave components and the sum frequency component are separately subjected to homodyne detection, and the AC signal having the frequency of the sum of the AC signals of the two fundamental wave components generated by the optical path difference modulation is used as a reference signal. The amplitude and phase difference of the sum frequency component of the light generated in the sample to be measured are measured.
[0011]
[7] In the optical amplitude and phase characteristic measuring device, two light sources having different wavelengths, an optical multiplexer for combining the fundamental wave components of the output light of the two light sources, and an optical path of the output of the optical multiplexer are arranged. A sample to be measured that generates a difference frequency component, an optical branching device that branches two fundamental wave components and the difference frequency component simultaneously, means for modulating the optical path difference of one of the outputs of the optical branching device, An optical multiplexer that multiplexes two fundamental wave components and the difference frequency component generated in the sample to be measured, and an optical demultiplexer that demultiplexes the output light of the optical multiplexer into two fundamental wave components and a difference frequency component Two optical detection means for detecting two fundamental wave components of the output of the optical demultiplexer, a means for generating a difference frequency component of two AC signals of the output of the optical detection means, and the optical division Means for detecting the difference frequency component of the output of the wave generator and the output of the difference frequency component It is obtained so as to provide a means for detecting the amplitude and phase difference of the AC signal.
[0012]
[8] In the optical amplitude phase characteristic measurement method, two light sources having different wavelengths, an optical multiplexer for combining the fundamental wave components of the output light of the two light sources, and an optical path of the output of the optical multiplexer are arranged. A sample to be measured that generates a difference frequency component, an optical branching device that branches two fundamental wave components and the difference frequency component simultaneously, means for modulating the optical path difference of one of the outputs of the optical branching device, An optical multiplexer that multiplexes two fundamental wave components and the difference frequency component generated in the sample to be measured, and an optical demultiplexer that demultiplexes the output light of the optical multiplexer into two fundamental wave components and a difference frequency component Two optical detection means for detecting two fundamental wave components of the output of the optical demultiplexer, a means for generating a difference frequency component of two AC signals of the output of the optical detection means, and the optical division Means for detecting the difference frequency component of the output of the wave generator and the output of the difference frequency component And means for detecting the amplitude and phase difference of the AC signal is disposed,
After combining the fundamental wave components of the output light of the two light sources with the optical multiplexer, the fundamental wave component of the output light and the difference frequency component generated in the sample to be measured are branched, and either one of the optical path differences The two fundamental wave components and the difference frequency component are separately subjected to homodyne detection, and the AC signal of the frequency difference between the two AC signals generated by the modulation of the optical path difference is used as a reference signal. , The amplitude and phase difference of the difference frequency component of the light generated in the sample to be measured are measured.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, a first embodiment of the present invention will be described.
FIG. 1 is a block diagram of an optical phase characteristic measuring apparatus showing a first embodiment of the present invention.
As shown in this figure, the optical amplitude phase measuring apparatus of this embodiment includes a first light source 1, a second light source 2, an optical branching device 3, a sum frequency generating element 4, a mirror 5, a sample 6 to be measured, an optical path. Difference modulation signal generator 7, optical path difference modulation mirror 8, optical multiplexer 9, first optical demultiplexer 10, second optical demultiplexer 11, third optical demultiplexer 12, fourth Optical demultiplexer 13, first optical detector 14, second optical detector 15, third optical detector 16, fourth optical detector 17, fifth optical detector 18, sixth light It comprises a detector 19, a first differential amplifier 20, a second differential amplifier 21, a third differential amplifier 22, a modulator 23, and a synchronization detector 24.
[0014]
Here, the optical branching device 3 branches two fundamental wave components simultaneously, and the optical multiplexer 9 combines the fundamental wave component and the sum frequency component at the same time, and is a half mirror, a non-polarizing beam splitter. A polarizing beam splitter, an optical directional coupler, or the like can be used.
The sum frequency generating element 4 is used as a means for generating a sum frequency component from the fundamental wave of the two light sources, and the optical path difference modulation signal generator 7 and the optical path difference modulation mirror 8 are used as means for modulating the optical path difference. The demultiplexers 10, 11, 12, and 13 are means for demultiplexing the fundamental wave component and the sum frequency component. The optical detectors 14 and 15, the differential amplifier 20, the optical detectors 16, 17 and the differential amplifier 21 are fundamental. The optical detectors 18 and 19 and the differential amplifier 22 are used as means for detecting wave components, the sum frequency component is used as detector means, the modulator 23 is used as means for generating a sum frequency component of AC signals, and the synchronous detector 24 is used. Each corresponds to a means for detecting an amplitude and a phase difference.
[0015]
The sum frequency generation element 4 uses a nonlinear optical crystal in order to efficiently generate the sum frequency component on the local light emission side.
Further, it is sufficient for the optical path difference modulation mirror 8 to be able to obtain vibrations several times the wavelength of the light, and a piezo element with an optical mirror attached thereto can be used. Furthermore, this action changes the phase of light continuously, and any action can be used as long as an equivalent phase change can be obtained.
[0016]
Further, the optical demultiplexers 10, 11, 12, and 13 demultiplex the fundamental wave component and the sum frequency component, and a spectral prism, a dichroic mirror, or the like can be used. Further, it is possible to use a configuration of a demultiplexer that integrates the optical demultiplexers 10 and 13 and demultiplexes the fundamental wave component and the sum frequency component simultaneously.
Further, there is a method of using one optical detector by using the outputs of the optical demultiplexers 12 and 13 as optical detectors. However, as shown in this embodiment, two optical detectors 14 and 15 and a differential are used. The configuration of balanced detection by the combination of the amplifier 20, the two optical detectors 16 and 17 and the differential amplifier 21, and the two optical detectors 18 and 19 and the differential amplifier 22 is the output light of the light source. Is suppressed, and the noise of the measurement system becomes a shot noise level, so it is clear that the S / N ratio is improved and the sensitivity becomes high.
[0017]
Further, as the synchronization detector 24, a lock-in amplifier or the like can be used.
The operation of the optical phase characteristic measuring apparatus according to the first embodiment of the present invention will be described below.
The cause of the instability of the homodyne interferometer is a phase change due to fluctuations in the optical path difference of the interferometer. Generally, since the interferometer is stabilized by detecting this phase change and performing negative feedback control, it is difficult to separate the phase signal for measurement from the negative feedback control signal.
[0018]
Now, when one optical path difference is modulated without stabilizing the interferometer, the interference fringes change according to the modulation speed and amplitude, and an AC signal is generated. Since the amplitude of the AC signal matches the visibility of the interferometer, it is very stable (reference: Japanese Patent Application No. 8-185235). However, since the instability that occurs because the interferometer is not stabilized is converted into the phase of the AC signal, the amplitude and phase characteristics cannot be measured stably as it is.
[0019]
Therefore, when the second harmonic (frequency is doubled and wavelength is 1/2) generated by the output light of the light source, the phase characteristic can be measured very stably. (Reference: Japanese Patent Application No. 9-262064)
Now, assuming that the light frequencies of the two light sources are f o1 and f o2 , the frequency f os of this sum light is f os = f o1 + f o2 . Here, when the modulation waveform of the optical path difference of the interferometer is performed with a triangular wave, an AC signal corresponding to the modulation speed of the optical path difference is generated in the detection output. Assuming that the frequencies of the AC signals of the detection outputs for the two light sources and the sum frequency light are f r1 , f r2 and f rs , respectively, f r1 = f o1 / k, f r2 = f o2 / k, f rs = f os / k (k is a constant related to the modulation speed of the optical path difference). Therefore, the frequency f rs of the detection output of the sum frequency component is a frequency of the sum of f r1 and f r2.
[0020]
Here, the AC signal of the sum frequency f rr (f rr = f r1 + f r2 ) component synthesized from the AC signals of f r1 and f r2 stores the phase information of the light frequencies f o1 and f o2 . In addition, the AC signal component of the sum frequency f rr also stores the phase information of f o1 and f o2 .
Thus, as a reference signal an AC signal component of the frequency f rr sum, by detecting synchronizing an AC signal component f rs which detects the light of the sum frequency, to measure the amplitude and phase of the light sum frequency sensitive it can.
[0021]
Since this interferometer is a homodyne detection method, if one optical path is used as a local oscillation light and a sufficient amount of light is used, the intensity of the signal light in the other optical path can be made extremely small, and the phase characteristic has high sensitivity. Amplitude characteristics can be measured simultaneously with the measurement. Furthermore, the optical detector used here is sufficient in the bandwidth necessary for detecting the AC signal generated when the optical path difference is modulated, and does not require broadband characteristics.
[0022]
In FIG. 1, the output light of the first light source 1 and the second light source 2 is branched by an optical branching device 3, and one of them generates a sum frequency component by a sum frequency generating element 4, and two fundamental wave components. And the sum frequency component as local oscillation light of homodyne detection. At this time, the fundamental wave component and the sum frequency component of the output of the sum frequency generation element 4 are reflected by the mirror 5, and all components are guided to the optical multiplexer 9.
[0023]
The other branched by the optical branching unit 3 is incident on the sample 6 to be measured as signal light, and the sum frequency component and the fundamental wave component generated by the sample 6 to be measured are an optical path difference modulation signal generator. The light is reflected by the optical path difference modulation mirror 8 operating at 7, and all components are guided to the optical multiplexer 9.
The three sets of components multiplexed by the optical multiplexer 9 are demultiplexed into a fundamental wave component and a sum frequency component by the first optical demultiplexer 10 and the second optical demultiplexer 11, respectively.
[0024]
The fundamental wave components demultiplexed by the first optical demultiplexer 10 and the second optical demultiplexer 11 are further divided into two components by the third optical demultiplexer 12 and the fourth optical demultiplexer 13, respectively. The first optical detector 14, the second optical detector 15, the first differential amplifier 20, the third optical detector 16, the fourth optical detector 17, and the second optical detector 14 are demultiplexed into fundamental wave components. The differential amplifier 21 detects and amplifies. Of the output signals of the first differential amplifier 20 and the second differential amplifier 21, an AC signal component generated by the modulation of the optical path difference is guided to the modulator 23. The modulator 23 generates a frequency that is the sum of two AC signal components based on the fundamental wave, and connects it to the reference signal input terminal of the synchronization detector 24.
[0025]
On the other hand, the sum frequency components demultiplexed by the first optical demultiplexer 10 and the second optical demultiplexer 11 are the fifth optical detector 18, the sixth optical detector 19, and the third differential amplifier. The signal is detected and amplified at 22 and connected to the signal input terminal of the synchronous detector 24.
In addition, since the frequency of the reference signal generated by the modulator 23 and the frequency of the signal light component detected from the sum frequency component are always equal even if the interferometer fluctuates, the synchronization detector 24 The signal light component can be measured with high sensitivity.
[0026]
Next, a method for measuring the amplitude and phase difference of the sum frequency component generated in the sample to be measured will be described using the first embodiment.
(1) The output light from the two light sources 1 and 2 is demultiplexed simultaneously.
(2) The branching ratio of the optical branching unit 3 is adjusted to set a necessary and sufficient amount of light on the local light emission side.
[0027]
(3) A sum frequency light is generated by the nonlinear optical crystal 4 as the sum frequency generation element 4 inserted on the local light emission side, and is guided to the optical multiplexer 9 simultaneously with the two fundamental waves.
(4) The transmitted light, reflected light, or emitted light of the sum frequency from the non-measurement sample 6 installed on the signal light side and the two fundamental wave components are the optical path that operates with the triangular wave of the signal generator 7 for optical path difference modulation. Modulation is performed simultaneously by the difference modulation mirror 8 and combined with the local light component by the optical multiplexer 9.
(5) Each output light of the optical multiplexer 9 is demultiplexed into a fundamental wave component and a sum frequency component by the first optical demultiplexer 10 and the second optical demultiplexer 11, and the fundamental wave component is The third optical demultiplexer 12 and the fourth optical demultiplexer 13 demultiplex each fundamental wave.
[0028]
(6) The components demultiplexed by the first to fourth optical demultiplexers 10, 11, 12, and 13 are detected and amplified to output three AC signal components.
(7) Of these, the two alternating current signals of the fundamental wave are summed by the modulator 23 and connected to the reference signal input terminal of the synchronous detector 24.
(8) The AC signal by the sum frequency is connected to the signal input terminal of the synchronization detector 24, and the phase difference between the amplitude of the sum frequency component and the reference signal is obtained.
[0029]
A second embodiment of the present invention will be described.
FIG. 2 is a block diagram of an optical phase characteristic measuring apparatus showing a second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the part similar to 1st Example, and those description is abbreviate | omitted.
As shown in this figure, the optical amplitude phase measuring apparatus of this embodiment is different from that of the first embodiment in that an optical multiplexer 25 and an optical branching device 31 are provided, and the rest is substantially the same as the first embodiment. It is a configuration.
[0030]
Here, the optical multiplexer 25 combines the two fundamental wave components from the first light source 1 and the second light source 2, and the optical splitter 31 simultaneously combines the two fundamental wave components and the sum frequency component. For example, a half mirror, a non-polarizing beam splitter, a polarizing beam splitter, or a light directional coupler can be used.
The operation of the optical amplitude phase measuring apparatus of this embodiment will be described below.
[0031]
In FIG. 2, the output light of the first light source 1 and the second light source 2 is combined by an optical multiplexer 25, and the output is incident on the sample 6 to be measured to generate a sum frequency component. The two fundamental wave components and the sum frequency component are branched at the same time by the optical branching unit 31, and the two fundamental wave components and the sum frequency component are optically detected as homodyne detection signal light and local oscillation light as in the first embodiment. Then, the amplitude and phase of the sum frequency component are measured.
[0032]
Although the sum frequency generating element is used in the first and second embodiments, if this is used as the difference frequency generating element and the output of the modulator is the difference frequency of the AC signal components of the two fundamental waves, the non-measurement sample It is possible to measure the amplitude and phase difference of the difference frequency component generated in the above.
That is, the frequency of light f od difference, and the frequency of the signal obtained by detecting the difference frequency component is f rd, because it is f rd = (f o1 -f 02 ) / k = f r1 -f r2, the above-mentioned Similarly to the sum frequency, the detection signal of the difference frequency component of light can be synchronously detected using the frequency component of the difference between the two fundamental wave components generated by the modulator as a reference signal.
[0033]
Further, in the first and second embodiments, the configuration of the Mach-Zehnder interferometer is shown, but the same operation can be performed even in the configuration of the Michelson interferometer. Furthermore, it is possible to use components using optical fibers.
In addition, this invention is not limited to the said Example, A various deformation | transformation is possible based on the meaning of this invention, and these are not excluded from the scope of the present invention.
[0034]
【The invention's effect】
As described above in detail, according to the present invention, the following effects can be obtained.
(A) Stabilize the interferometer to measure the AC signal component generated by modulating the optical path difference for the two fundamental waves of the light source and the light of the sum or difference frequency that has phase correlation with them. There is no need to make it, and it is very stable.
[0035]
(B) Furthermore, since the homodyne detection method and the phase locked detector are used, the sensitivity is very high and the amplitude characteristic and the phase characteristic can be measured simultaneously.
(C) Further, the frequency characteristic of the optical detector does not require a broadband characteristic, and the configuration is simple.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an optical phase characteristic measuring apparatus according to a first embodiment of the present invention.
FIG. 2 is a configuration diagram of an optical phase characteristic measuring apparatus showing a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 1st light source 2 2nd light source 3,31 Optical branching device 4 Sum frequency generation element (nonlinear optical element)
DESCRIPTION OF SYMBOLS 5 Mirror 6 Sample 7 Optical path difference modulation signal generator 8 Optical path difference modulation mirror 9, 25 Optical multiplexers 10, 11, 12, 13 Optical demultiplexers (first to fourth optical demultiplexers)
14, 15, 16, 17, 18, 19 Optical detectors (first to sixth optical detectors)
20, 21, 22 Differential amplifier (first to third differential amplifiers)
23 Modulator 24 Synchronization detector

Claims (8)

光振幅位相特性測定装置において、
（ａ）二つの波長の異なる光源と、
（ｂ）前記二つの光源の出力光の基本波成分を分岐する光分岐器と、
（ｃ）該光分岐器の出力のどちらか一方の光路に配置される被測定試料と、
（ｄ）前記光分岐器の出力の他方の光路に前記二つの光源の基本波の和周波成分を発生させる手段と、
（ｅ）前記光分岐器の出力のどちらか一方の光路差を変調する手段と、
（ｆ）前記二つの基本波成分と前記被測定試料で発生した和周波成分を合波する光合波器と、
（ｇ）該光合波器の出力光を二つの基本波成分と和周波成分に分波する光分波器と、
（ｈ）該光分波器の出力の二つの基本波成分をそれぞれ検波する二つの光検波手段と、
（ｉ）該光検波手段の出力の二つの交流信号の和周波数成分を発生させる手段と、
（ｊ）前記光分波器の出力の和周波成分を検波する手段と、
（ｋ）該和周波成分の出力交流信号の振幅と位相差を検出する手段とを具備することを特徴とする光振幅位相特性測定装置。In the optical amplitude phase characteristic measuring device,
(A) two light sources having different wavelengths;
(B) an optical branching device for branching the fundamental wave component of the output light of the two light sources;
(C) a sample to be measured arranged in one of the optical paths of the output of the optical splitter;
(D) means for generating a sum frequency component of the fundamental wave of the two light sources in the other optical path of the output of the optical splitter;
(E) means for modulating the optical path difference of one of the outputs of the optical splitter;
(F) an optical multiplexer that combines the two fundamental wave components and the sum frequency component generated in the sample to be measured;
(G) an optical demultiplexer for demultiplexing the output light of the optical multiplexer into two fundamental wave components and a sum frequency component;
(H) two optical detection means for detecting each of the two fundamental wave components of the output of the optical demultiplexer;
(I) means for generating a sum frequency component of two AC signals output from the optical detection means;
(J) means for detecting the sum frequency component of the output of the optical demultiplexer;
(K) An optical amplitude phase characteristic measuring apparatus comprising: means for detecting an amplitude and a phase difference of an output AC signal of the sum frequency component. 光振幅位相特性測定方法において、
二つの波長の異なる光源と、前記二つの光源の出力光の基本波成分を分岐する光分岐器と、該光分岐器の出力のどちらか一方の光路に配置される被測定試料と、前記光分岐器の出力の他方の光路に前記二つの光源の基本波の和周波成分を発生させる手段と、前記光分岐器の出力のどちらか一方の光路差を変調する手段と、前記二つの基本波成分と前記被測定試料で発生した和周波成分を合波する光合波器と、該光合波器の出力光を二つの基本波成分と和周波成分に分波する光分波器と、該光分波器の出力の二つの基本波成分をそれぞれ検波する二つの光検波手段と、該光検波手段の出力の二つの交流信号の和周波数成分を発生させる手段と、前記光分波器の出力の和周波成分を検波する手段と、該和周波成分の出力交流信号の振幅と位相差を検出する手段とを配置し、
前記二つの光源の出力光の基本波成分を、前記光分岐器で分岐後、どちらか一方の光路差を変調して、前記二つの基本波成分と和周波成分をそれぞれ別々にホモダイン検波を行い、光路差の変調によって発生する二つの基本波成分による交流信号の和の周波数の交流信号を基準信号として、前記被測定試料で発生する光の和周波成分の振幅と位相差を測定することを特徴とする光振幅位相特性測定方法。In the optical amplitude phase characteristic measurement method,
Two light sources having different wavelengths, an optical branching device for branching the fundamental wave component of the output light of the two light sources, a sample to be measured arranged in one of the optical paths of the output of the optical branching device, and the light Means for generating the sum frequency component of the fundamental wave of the two light sources in the other optical path of the output of the splitter, means for modulating the optical path difference of one of the outputs of the optical splitter, and the two fundamental waves An optical multiplexer for combining the component and the sum frequency component generated in the sample to be measured, an optical demultiplexer for demultiplexing the output light of the optical multiplexer into two fundamental wave components and a sum frequency component, and the light Two optical detection means for detecting the two fundamental wave components of the output of the duplexer, means for generating the sum frequency component of the two AC signals of the output of the optical detection means, and the output of the optical splitter Means for detecting the sum frequency component of the signal, and the amplitude and phase difference of the output AC signal of the sum frequency component And means arranged to be out,
After the fundamental wave components of the output light of the two light sources are branched by the optical splitter, the optical path difference of either one is modulated, and the two fundamental wave components and the sum frequency component are separately subjected to homodyne detection. Measuring the amplitude and phase difference of the sum frequency component of the light generated in the sample to be measured, using the AC signal having the frequency of the sum of the AC signals of the two fundamental wave components generated by the modulation of the optical path difference as a reference signal. A characteristic optical amplitude phase characteristic measuring method. 光振幅位相特性測定装置において、
（ａ）二つの波長の異なる光源と、
（ｂ）前記二つの光源の出力光の基本波成分を分岐する光分岐器と、
（ｃ）該光分岐器の出力のどちらか一方の光路に配置される被測定試料と、
（ｄ）前記光分岐器の出力の他方の光路に前記二つの光源の基本波の差周波成分を発生させる手段と、
（ｅ）前記光分岐器の出力のどちらか一方の光路差を変調する手段と、
（ｆ）前記二つの基本波成分と前記被測定試料で発生した差周波成分を合波する光合波器と、
（ｇ）該光合波器の出力光を二つの基本波成分と差周波成分に分波する光分波器と、
（ｈ）該光分波器の出力の二つの基本波成分をそれぞれ検波する二つの光検波手段と、
（ｉ）該光検波手段の出力の二つの交流信号の差周波数成分を発生させる手段と、
（ｊ）前記光分波器の出力の差周波成分を検波する手段と、
（ｋ）該差周波成分の出力交流信号の振幅と位相差を検出する手段とを具備することを特徴とする光振幅位相特性測定装置。In the optical amplitude phase characteristic measuring device,
(A) two light sources having different wavelengths;
(B) an optical branching device for branching the fundamental wave component of the output light of the two light sources;
(C) a sample to be measured arranged in one of the optical paths of the output of the optical splitter;
(D) means for generating a difference frequency component of the fundamental wave of the two light sources in the other optical path of the output of the optical splitter;
(E) means for modulating the optical path difference of one of the outputs of the optical splitter;
(F) an optical multiplexer for combining the two fundamental wave components and the difference frequency component generated in the sample to be measured;
(G) an optical demultiplexer for demultiplexing the output light of the optical multiplexer into two fundamental wave components and a difference frequency component;
(H) two optical detection means for detecting each of the two fundamental wave components of the output of the optical demultiplexer;
(I) means for generating a difference frequency component of two AC signals output from the optical detection means;
(J) means for detecting a difference frequency component of the output of the optical demultiplexer;
(K) An optical amplitude phase characteristic measuring apparatus comprising: means for detecting an amplitude and a phase difference of an output AC signal of the difference frequency component. 光振幅位相特性測定方法において、
二つの波長の異なる光源と、前記二つの光源の出力光の基本波成分を分岐する光分岐器と、該光分岐器の出力のどちらか一方の光路に配置される被測定試料と、前記光分岐器の出力の他方の光路に前記二つの光源の基本波の差周波成分を発生させる手段と、前記光分岐器の出力のどちらか一方の光路差を変調する手段と、前記二つの基本波成分と前記被測定試料で発生した差周波成分を合波する光合波器と、該光合波器の出力光を二つの基本波成分と差周波成分に分波する光分波器と、該光分波器の出力の二つの基本波成分をそれぞれ検波する二つの光検波手段と、該光検波手段の出力の二つの交流信号の差周波数成分を発生させる手段と、前記光分波器の出力の差周波成分を検波する手段と、該差周波成分の出力交流信号の振幅と位相差を検出する手段とを配置し、
前記二つの光源の出力光の基本波成分を、前記光分岐器で分岐後、どちらか一方の光路差を変調して、前記二つの基本波成分と差周波成分をそれぞれ別々にホモダイン検波を行い、光路差の変調によって発生する二つの基本波成分による交流信号の差の周波数の交流信号を基準信号として、前記被測定試料で発生する光の差周波成分の振幅と位相差を測定することを特徴とする光振幅位相特性測定方法。In the optical amplitude phase characteristic measurement method,
Two light sources having different wavelengths, an optical branching device for branching the fundamental wave component of the output light of the two light sources, a sample to be measured arranged in one of the optical paths of the output of the optical branching device, and the light Means for generating a difference frequency component of the fundamental wave of the two light sources in the other optical path of the output of the splitter, means for modulating the optical path difference of one of the outputs of the optical splitter, and the two fundamental waves An optical multiplexer for combining a component and a difference frequency component generated in the sample to be measured, an optical demultiplexer for demultiplexing the output light of the optical multiplexer into two fundamental wave components and a difference frequency component, and the light Two optical detection means for detecting two fundamental wave components of the output of the demultiplexer, means for generating a difference frequency component of the two AC signals of the output of the optical detection means, and the output of the optical demultiplexer Means for detecting the difference frequency component of the difference frequency component, and the amplitude and phase difference of the output AC signal of the difference frequency component And means arranged to be out,
After the fundamental wave component of the output light of the two light sources is branched by the optical splitter, the optical path difference of either one is modulated, and the two fundamental wave components and the difference frequency component are separately subjected to homodyne detection. Measuring the amplitude and phase difference of the difference frequency component of the light generated in the sample to be measured, using the AC signal of the frequency of the difference of the AC signal due to the two fundamental wave components generated by the modulation of the optical path difference as a reference signal. A characteristic optical amplitude phase characteristic measuring method. 光振幅位相特性測定装置において、
（ａ）二つの波長の異なる光源と、
（ｂ）前記二つの光源の出力光の基本波成分を合波する光合波器と、
（ｃ）該光合波器の出力の光路に配置され、和周波成分を発生させる被測定試料と、
（ｄ）二つの基本波成分と和周波成分を同時に分岐する光分岐器と、
（ｅ）該光分岐器の出力のどちらか一方の光路差を変調する手段と、
（ｆ）前記二つの基本波成分と前記被測定試料で発生した和周波成分を合波する光合波器と、
（ｇ）該光合波器の出力光を二つの基本波成分と和周波成分に分波する光分波器と、
（ｈ）該光分波器の出力の二つの基本波成分をそれぞれ検波する二つの光検波手段と、
（ｉ）該光検波手段の出力の二つの交流信号の和周波数成分を発生させる手段と、
（ｊ）前記光分波器の出力の和周波成分を検波する手段と、
（ｋ）該和周波成分の出力交流信号の振幅と位相差を検出する手段とを具備することを特徴とする光振幅位相特性測定装置。In the optical amplitude phase characteristic measuring device,
(A) two light sources having different wavelengths;
(B) an optical multiplexer that combines the fundamental wave components of the output light of the two light sources;
(C) a sample to be measured that is arranged in the optical path of the output of the optical multiplexer and generates a sum frequency component;
(D) an optical branching device that simultaneously branches two fundamental wave components and a sum frequency component;
(E) means for modulating the optical path difference of one of the outputs of the optical splitter;
(F) an optical multiplexer that combines the two fundamental wave components and the sum frequency component generated in the sample to be measured;
(G) an optical demultiplexer for demultiplexing the output light of the optical multiplexer into two fundamental wave components and a sum frequency component;
(H) two optical detection means for detecting each of the two fundamental wave components of the output of the optical demultiplexer;
(I) means for generating a sum frequency component of two AC signals output from the optical detection means;
(J) means for detecting the sum frequency component of the output of the optical demultiplexer;
(K) An optical amplitude phase characteristic measuring apparatus comprising: means for detecting an amplitude and a phase difference of an output AC signal of the sum frequency component. 光振幅位相特性測定方法において、
二つの波長の異なる光源と、前記二つの光源の出力光の基本波成分を合波する光合波器と、該光合波器の出力の光路に配置され、和周波成分を発生させる被測定試料と、二つの基本波成分と和周波成分を同時に分岐する光分岐器と、該光分岐器の出力のどちらか一方の光路差を変調する手段と、前記二つの基本波成分と前記被測定試料で発生した和周波成分を合波する光合波器と、該光合波器の出力光を二つの基本波成分と和周波成分に分波する光分波器と、該光分波器の出力の二つの基本波成分をそれぞれ検波する二つの光検波手段と、該光検波手段の出力の二つの交流信号の和周波数成分を発生させる手段と、前記光分波器の出力の和周波成分を検波する手段と、該和周波成分の出力交流信号の振幅と位相差を検出する手段とを配置し、
前記二つの光源の出力光の基本波成分を、前記光合波器で合波後、前記出力光の基本波成分と前記被測定試料で発生する和周波成分とを分岐し、どちらか一方の光路差を変調して、前記二つの基本波成分と和周波成分をそれぞれ別々にホモダイン検波を行い、光路差の変調によって発生する二つの基本波成分による交流信号の和の周波数の交流信号を基準信号として、前記被測定試料で発生する光の和周波成分の振幅と位相差を測定することを特徴とする光振幅位相特性測定方法。In the optical amplitude phase characteristic measurement method,
Two light sources having different wavelengths, an optical multiplexer for combining the fundamental wave components of the output light of the two light sources, a sample to be measured that is arranged in the optical path of the output of the optical multiplexer and generates a sum frequency component; An optical branching device for simultaneously branching two fundamental wave components and a sum frequency component, means for modulating the optical path difference of one of the outputs of the optical branching device, the two fundamental wave components and the sample to be measured. An optical multiplexer for multiplexing the generated sum frequency component, an optical demultiplexer for demultiplexing the output light of the optical multiplexer into two fundamental wave components and a sum frequency component, and an output of the optical demultiplexer Two optical detection means for detecting each of the fundamental components, means for generating a sum frequency component of two AC signals output from the light detection means, and detecting the sum frequency component of the output of the optical demultiplexer And means for detecting the amplitude and phase difference of the output AC signal of the sum frequency component,
After combining the fundamental wave components of the output light of the two light sources with the optical multiplexer, the fundamental wave component of the output light and the sum frequency component generated in the sample to be measured are branched, and either one of the optical paths The difference is modulated, and the two fundamental wave components and the sum frequency component are separately subjected to homodyne detection, and the AC signal having the frequency of the sum of the AC signals of the two fundamental wave components generated by the modulation of the optical path difference is used as a reference signal. And measuring the amplitude and phase difference of the sum frequency component of the light generated in the sample to be measured. 光振幅位相特性測定装置において、
（ａ）二つの波長の異なる光源と、
（ｂ）前記二つの光源の出力光の基本波成分を合波する光合波器と、
（ｃ）該光合波器の出力の光路に配置され、差周波成分を発生させる被測定試料と、
（ｄ）二つの基本波成分と差周波成分を同時に分岐する光分岐器と、
（ｅ）該光分岐器の出力のどちらか一方の光路差を変調する手段と、
（ｆ）前記二つの基本波成分と前記被測定試料で発生した差周波成分を合波する光合波器と、
（ｇ）該光合波器の出力光を二つの基本波成分と差周波成分に分波する光分波器と、
（ｈ）該光分波器の出力の二つの基本波成分をそれぞれ検波する二つの光検波手段と、
（ｉ）該光検波手段の出力の二つの交流信号の差周波数成分を発生させる手段と、
（ｊ）前記光分波器の出力の差周波成分を検波する手段と、
（ｋ）該差周波成分の出力交流信号の振幅と位相差を検出する手段とを具備することを特徴とする光振幅位相特性測定装置。In the optical amplitude phase characteristic measuring device,
(A) two light sources having different wavelengths;
(B) an optical multiplexer that combines the fundamental wave components of the output light of the two light sources;
(C) a sample to be measured that is arranged in the optical path of the output of the optical multiplexer and generates a difference frequency component;
(D) an optical branching device that simultaneously branches two fundamental wave components and a difference frequency component;
(E) means for modulating the optical path difference of one of the outputs of the optical splitter;
(F) an optical multiplexer for combining the two fundamental wave components and the difference frequency component generated in the sample to be measured;
(G) an optical demultiplexer for demultiplexing the output light of the optical multiplexer into two fundamental wave components and a difference frequency component;
(H) two optical detection means for detecting each of the two fundamental wave components of the output of the optical demultiplexer;
(I) means for generating a difference frequency component of two AC signals output from the optical detection means;
(J) means for detecting a difference frequency component of the output of the optical demultiplexer;
(K) An optical amplitude phase characteristic measuring apparatus comprising: means for detecting an amplitude and a phase difference of an output AC signal of the difference frequency component. 光振幅位相特性測定方法において、
二つの波長の異なる光源と、前記二つの光源の出力光の基本波成分を合波する光合波器と、該光合波器の出力の光路に配置され、差周波成分を発生させる被測定試料と、二つの基本波成分と差周波成分を同時に分岐する光分岐器と、該光分岐器の出力のどちらか一方の光路差を変調する手段と、前記二つの基本波成分と前記被測定試料で発生した差周波成分を合波する光合波器と、該光合波器の出力光を二つの基本波成分と差周波成分に分波する光分波器と、該光分波器の出力の二つの基本波成分をそれぞれ検波する二つの光検波手段と、該光検波手段の出力の二つの交流信号の差周波数成分を発生させる手段と、前記光分波器の出力の差周波成分を検波する手段と、該差周波成分の出力交流信号の振幅と位相差を検出する手段とを配置し、
前記二つの光源の出力光の基本波成分を、前記光合波器で合波後、前記出力光の基本波成分と前記被測定試料で発生する差周波成分とを分岐し、どちらか一方の光路差を変調して、前記二つの基本波成分と差周波成分をそれぞれ別々にホモダイン検波を行い、光路差の変調によって発生する二つの基本波成分による交流信号の差の周波数の交流信号を基準信号として、前記被測定試料で発生する光の差周波成分の振幅と位相差を測定することを特徴とする光振幅位相特性測定方法。In the optical amplitude phase characteristic measurement method,
Two light sources having different wavelengths, an optical multiplexer that combines the fundamental wave components of the output light of the two light sources, a sample to be measured that is arranged in the optical path of the output of the optical multiplexer and generates a difference frequency component; An optical branching device for simultaneously branching two fundamental wave components and a difference frequency component, means for modulating the optical path difference of one of the outputs of the optical branching device, the two fundamental wave components and the sample to be measured. An optical multiplexer for multiplexing the generated difference frequency component, an optical demultiplexer for demultiplexing the output light of the optical multiplexer into two fundamental wave components and a difference frequency component, and an output of the optical demultiplexer Two optical detection means for detecting two fundamental wave components, means for generating a difference frequency component of two AC signals output from the optical detection means, and detecting a difference frequency component of the output of the optical demultiplexer Means and means for detecting the amplitude and phase difference of the output AC signal of the difference frequency component,
After combining the fundamental wave components of the output light of the two light sources with the optical multiplexer, the fundamental wave component of the output light and the difference frequency component generated in the sample to be measured are branched, and either one of the optical paths The difference is modulated, the two fundamental wave components and the difference frequency component are separately subjected to homodyne detection, and the AC signal having the frequency difference between the two fundamental wave components generated by the modulation of the optical path difference is used as a reference signal. And measuring the amplitude and phase difference of the difference frequency component of the light generated in the sample to be measured.
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EP98118233A EP0908710B1 (en) 1997-09-26 1998-09-25 Apparatus and method for measuring characteristics of light
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