報告書番号

R96014

タイトル（和文）

光偏波制御装置の開発と実証

タイトル（英文）

概要 （図表や脚注は「報告書全文」に掲載しております）

４つの側面に電極を蒸着したｚ伝搬ＬＮ（ニオブ酸リチウム）結晶を用いた偏波制御装置を開発した。本装置は入力光の偏波状態から算出した２つの電圧を直接１つのＬＮ結晶に加えて右回り円偏光に制御した後，波長板で直線偏光に変換する。実験の結果，出力光の９９％以上が目的の偏波状態になり，入力偏波検出用の分岐損失１．３ｄＢを含む全挿入損失は２．９ｄＢ以下，出力変動幅は０．２ｄＢ以下である。また，任意の方向に無限に続く偏波変動に対して無限追従を実現するとともにパソコンで速度６０ｋＨｚの制御を達成した。雷撃による偏波変動に対応するには１００ｋＨｚ以上にする必要があるが，演算装置等の改良により可能と考えられる。

概要 （英文）

THIS REPORT DESCRIBES A NEW FAST CONTROL SYSTEM FOR OPTICAL POLARIZATION AND SOME EXPERIMENTAL RESULTS;THE THEORY HAS BEEN PROPOSED IN A PREVIOUS REPORT.THE SYSTEM CHANGES ANY STATE OF POLARIZATION(SOP)TO RIGHT CIRCULAR POLARIZATION BY A Z-PROPAGATION LN(LINBO3)CRYSTAL WITH 4-ELECTRODES.THE ORTHOGONAL VOLTAGES VX AND VY ARE CALCULATED FROM THE INPUT SOP AND APPLIED.THE SOP IS CHANGED TO HORIZONTAL LINEAR POLARIZATION BY A QUARTER WAVE PLATE AND THE POWER IS MEASUREDTHROUGH A POLARIZATION SPLITTER.THE SIZE OF THE LN IS OPTIMIZED TO 1.5*1.5*40 MM AND THE WIDTH OF THE ELECTRODE IS 0.7 MM.AS A RESULT,TOTAL INSERTION LOSS WAS 2.9 DB INCLUDING A 3:1 BRANCH LOSS(1.3 DB)FOR DETECTING INPUT SOP.THE POLARIZATION EXTINCTION RATIO WAS 24 DB AND THE OUTPUTDEVIATION WAS UNDER 0.2DB.THIS MEANS THAT DISTORTION OF ELECTRIC FIELDDISTRIBUTION OR UNDESIRABLE BIREFRINGENCE IN THE LN IS SMALL.THE CONTROL CYCLE IS 60 KHZ USING A PERSONAL COMPUTER,INCLUDING AN ENDLESS CONTROL PROCESS WHICH DRIVES THE VOLTAGES VX AND VY LIKE ROTATION OF AN ELECTRIC FIELD VECTOR WHEN THE INPUT SOP CROSSES THE LEFT CIRCULAR POLARIZATION AND THE VOLTAGES TURN OVER.AS A RESULT THE OUTPUT POWER WAS KEPT BELAW A 1 DB DROP DUE TO THE CONTROL DELAY TIME(16.6 MU S).THE OUTPUT WAS ALSO STABLE WHEN THE INPUT SOP WAS CONSTANT.SO THIS SYSTEM COVERS THESOP FLUCTUATION FROM DC TO 20 OR 30 KHZ.ALTHOUGH A CONTROL CYCLE OF 100 KHZ IS NECESSARY FOR POLARIZATION FLUCTUATION CAUSED BY LIGHTNING ON AN OPGW,THIS SYSTEM HAS THE POTENTIAL TO ACHIEVE IT.

報告者

キーワード