實驗名稱：液晶填充的光子晶體光纖耦(ou)合器件及(ji)傳感特性

　　研究方向：將一種向列型液(ye)晶填入到PCF最內圈的(de)(de)一個空氣(qi)孔中(zhong)制成(cheng)一種PCF定(ding)向耦合結構，并且詳細研究了該結構透射光(guang)譜對(dui)外部電場的(de)(de)響應及其相應的(de)(de)電光(guang)開關和(he)電光(guang)調制特性。

　　測試設備：高壓放大器、信號發(fa)生器、示波器、可調(diao)諧激光(guang)器、光(guang)電(dian)探測器等。

　　實驗過程：

　　圖1：（a）樣品透射光譜(pu)隨施加(jia)電壓增加(jia)的變化(hua),（b）耦合峰波(bo)長與施加(jia)電壓的關(guan)系(xi)

　　實驗時(shi)首先在(zai)(zai)導(dao)電(dian)(dian)(dian)(dian)(dian)玻璃上(shang)施(shi)加一個(ge)頻率(lv)固定為(wei)1000Hz的(de)(de)(de)(de)(de)(de)正(zheng)弦(xian)電(dian)(dian)(dian)(dian)(dian)壓(ya)，并(bing)將(jiang)這(zhe)個(ge)正(zheng)弦(xian)電(dian)(dian)(dian)(dian)(dian)壓(ya)的(de)(de)(de)(de)(de)(de)有(you)效(xiao)值從0逐步增(zeng)加到(dao)(dao)130Vrms，樣品透射(she)譜隨(sui)施(shi)加電(dian)(dian)(dian)(dian)(dian)壓(ya)增(zeng)加的(de)(de)(de)(de)(de)(de)變(bian)(bian)化(hua)(hua)情況如圖1（a）所示，這(zhe)里(li)選擇監測(ce)1365nm處耦合峰(feng)的(de)(de)(de)(de)(de)(de)變(bian)(bian)化(hua)(hua)情況并(bing)將(jiang)這(zhe)個(ge)峰(feng)記為(wei)DipA，可以看到(dao)(dao)，在(zai)(zai)施(shi)加的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)達到(dao)(dao)60Vrms之前(qian)，樣品的(de)(de)(de)(de)(de)(de)光譜基本不(bu)發生(sheng)變(bian)(bian)化(hua)(hua)，當電(dian)(dian)(dian)(dian)(dian)壓(ya)從60Vrms增(zeng)加到(dao)(dao)80Vrms時(shi)，這(zhe)個(ge)耦合峰(feng)的(de)(de)(de)(de)(de)(de)波長位置向長波方向飄(piao)移到(dao)(dao)接近(jin)1400nm，并(bing)且在(zai)(zai)實驗中(zhong)觀(guan)察到(dao)(dao)這(zhe)個(ge)過程為(wei)非(fei)線性的(de)(de)(de)(de)(de)(de)飄(piao)移，這(zhe)歸(gui)因于液晶(jing)折射(she)率(lv)發生(sheng)了(le)不(bu)規(gui)(gui)則(ze)的(de)(de)(de)(de)(de)(de)輕(qing)(qing)微(wei)(wei)(wei)變(bian)(bian)化(hua)(hua)。通常液晶(jing)分(fen)子(zi)具有(you)一個(ge)閾值電(dian)(dian)(dian)(dian)(dian)壓(ya)用來克服表面錨定能和分(fen)子(zi)熱運動行為(wei)，在(zai)(zai)施(shi)加的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)低于這(zhe)個(ge)閾值電(dian)(dian)(dian)(dian)(dian)壓(ya)時(shi)，PCF空(kong)氣孔中(zhong)液晶(jing)分(fen)子(zi)的(de)(de)(de)(de)(de)(de)排列隨(sui)著施(shi)加電(dian)(dian)(dian)(dian)(dian)壓(ya)的(de)(de)(de)(de)(de)(de)增(zeng)大不(bu)發生(sheng)變(bian)(bian)化(hua)(hua)或者開始產生(sheng)輕(qing)(qing)微(wei)(wei)(wei)的(de)(de)(de)(de)(de)(de)不(bu)規(gui)(gui)則(ze)偏轉，進而導(dao)致液晶(jing)折射(she)率(lv)發生(sheng)輕(qing)(qing)微(wei)(wei)(wei)的(de)(de)(de)(de)(de)(de)變(bian)(bian)化(hua)(hua)，最終(zhong)反(fan)映到(dao)(dao)器件(jian)的(de)(de)(de)(de)(de)(de)光譜從最開始的(de)(de)(de)(de)(de)(de)沒有(you)變(bian)(bian)化(hua)(hua)到(dao)(dao)發生(sheng)輕(qing)(qing)微(wei)(wei)(wei)的(de)(de)(de)(de)(de)(de)非(fei)線性飄(piao)移。

　　從圖1（a）可(ke)(ke)以(yi)(yi)(yi)看到(dao)，通過(guo)施加(jia)不同有效(xiao)值的(de)正弦電壓，可(ke)(ke)以(yi)(yi)(yi)控制液體(ti)填(tian)充(chong)的(de)PCF中(zhong)某(mou)個(ge)特定波長光的(de)透過(guo)率，在施加(jia)合適(shi)的(de)電壓值并(bing)且器(qi)件(jian)(jian)耦合峰的(de)深度足(zu)夠時(shi)，甚至(zhi)可(ke)(ke)以(yi)(yi)(yi)實(shi)現光的(de)開啟與(yu)完全(quan)關斷，同時(shi)在實(shi)驗中(zhong)發現當電壓施加(jia)到(dao)器(qi)件(jian)(jian)上(shang)時(shi)，樣品透射光譜的(de)變化(hua)沒有明顯延時(shi)，這(zhe)使得(de)本文所提出的(de)器(qi)件(jian)(jian)可(ke)(ke)以(yi)(yi)(yi)用作一個(ge)全(quan)光纖的(de)快速電光開關。

　　實驗結果：

　　下(xia)面(mian)對(dui)器(qi)件的(de)(de)(de)(de)(de)(de)(de)電(dian)光(guang)(guang)開(kai)關特(te)性進(jin)行實(shi)(shi)驗(yan)研究，實(shi)(shi)驗(yan)中需要使(shi)用一臺可調諧(xie)激光(guang)(guang)器(qi)輸出(chu)(chu)(chu)單波(bo)長(chang)激光(guang)(guang)，利(li)用單模光(guang)(guang)纖(xian)將(jiang)激光(guang)(guang)器(qi)輸出(chu)(chu)(chu)的(de)(de)(de)(de)(de)(de)(de)光(guang)(guang)引入到(dao)液(ye)晶(jing)填(tian)充(chong)的(de)(de)(de)(de)(de)(de)(de)PCF中，從(cong)PCF輸出(chu)(chu)(chu)的(de)(de)(de)(de)(de)(de)(de)光(guang)(guang)通過另一段單模光(guang)(guang)纖(xian)輸入到(dao)一個光(guang)(guang)電(dian)探(tan)(tan)測器(qi)，光(guang)(guang)電(dian)探(tan)(tan)測器(qi)的(de)(de)(de)(de)(de)(de)(de)輸出(chu)(chu)(chu)端連接到(dao)一個示(shi)波(bo)器(qi)上。光(guang)(guang)電(dian)探(tan)(tan)測器(qi)接收(shou)樣(yang)(yang)品(pin)(pin)輸出(chu)(chu)(chu)的(de)(de)(de)(de)(de)(de)(de)光(guang)(guang)并(bing)將(jiang)光(guang)(guang)信(xin)(xin)(xin)號(hao)(hao)轉化(hua)為(wei)電(dian)信(xin)(xin)(xin)號(hao)(hao)后(hou)在(zai)示(shi)波(bo)器(qi)上顯示(shi)，實(shi)(shi)驗(yan)中通過監(jian)測示(shi)波(bo)器(qi)中的(de)(de)(de)(de)(de)(de)(de)波(bo)形研究器(qi)件的(de)(de)(de)(de)(de)(de)(de)開(kai)關響應特(te)性。仍(reng)舊使(shi)用上文中的(de)(de)(de)(de)(de)(de)(de)信(xin)(xin)(xin)號(hao)(hao)發(fa)(fa)生器(qi)和(he)高壓放(fang)大器(qi)將(jiang)電(dian)信(xin)(xin)(xin)號(hao)(hao)施(shi)加到(dao)ITO玻(bo)璃(li)上對(dui)PCF樣(yang)(yang)品(pin)(pin)進(jin)行電(dian)調制。首先使(shi)用可調諧(xie)激光(guang)(guang)器(qi)輸出(chu)(chu)(chu)1550nm的(de)(de)(de)(de)(de)(de)(de)單波(bo)長(chang)光(guang)(guang)，并(bing)測試在(zai)該(gai)波(bo)長(chang)光(guang)(guang)輸入情況(kuang)下(xia)本器(qi)件實(shi)(shi)現全(quan)光(guang)(guang)纖(xian)電(dian)光(guang)(guang)開(kai)關的(de)(de)(de)(de)(de)(de)(de)最佳正弦電(dian)壓大小和(he)頻(pin)率(lv)。接下(xia)來在(zai)信(xin)(xin)(xin)號(hao)(hao)發(fa)(fa)生器(qi)中使(shi)用頻(pin)率(lv)為(wei)1kHz的(de)(de)(de)(de)(de)(de)(de)不同電(dian)壓有效值的(de)(de)(de)(de)(de)(de)(de)正弦信(xin)(xin)(xin)號(hao)(hao)作(zuo)為(wei)載波(bo)，并(bing)使(shi)用周(zhou)期為(wei)0.4ms的(de)(de)(de)(de)(de)(de)(de)方波(bo)信(xin)(xin)(xin)號(hao)(hao)作(zuo)為(wei)調制波(bo)對(dui)載波(bo)進(jin)行振幅調制，調制深度(du)為(wei)100%，這樣(yang)(yang)實(shi)(shi)驗(yan)中可獲得一個間斷的(de)(de)(de)(de)(de)(de)(de)正弦電(dian)壓信(xin)(xin)(xin)號(hao)(hao)從(cong)信(xin)(xin)(xin)號(hao)(hao)發(fa)(fa)生器(qi)輸出(chu)(chu)(chu)，在(zai)經過高壓放(fang)大器(qi)的(de)(de)(de)(de)(de)(de)(de)放(fang)大后(hou)施(shi)加到(dao)ITO導電(dian)玻(bo)璃(li)上，從(cong)而(er)形成間斷的(de)(de)(de)(de)(de)(de)(de)空間電(dian)場作(zuo)用到(dao)液(ye)晶(jing)填(tian)充(chong)的(de)(de)(de)(de)(de)(de)(de)PCF上。

　　圖2：（a）不(bu)同電壓(ya)信(xin)號有效值(zhi)和（b）不(bu)同電壓(ya)信(xin)號頻率下器件(jian)的(de)開(kai)關響應(ying)

　　實驗中施加到導(dao)電(dian)(dian)(dian)(dian)玻璃(li)上(shang)的(de)(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)壓(ya)(ya)信(xin)號(hao)(hao)示意(yi)圖和不(bu)同(tong)電(dian)(dian)(dian)(dian)壓(ya)(ya)有(you)效(xiao)(xiao)值下(xia)的(de)(de)(de)(de)(de)(de)(de)器(qi)件(jian)(jian)(jian)(jian)開關(guan)響(xiang)應(ying)如圖2（a）所示，可以看出對(dui)(dui)于波(bo)(bo)長(chang)為(wei)1550nm的(de)(de)(de)(de)(de)(de)(de)輸入(ru)光(guang)，電(dian)(dian)(dian)(dian)壓(ya)(ya)有(you)效(xiao)(xiao)值在110Vrms時(shi)器(qi)件(jian)(jian)(jian)(jian)的(de)(de)(de)(de)(de)(de)(de)開關(guan)比最好。隨后研究電(dian)(dian)(dian)(dian)信(xin)號(hao)(hao)頻率(lv)對(dui)(dui)器(qi)件(jian)(jian)(jian)(jian)開關(guan)特性的(de)(de)(de)(de)(de)(de)(de)影響(xiang)，在固(gu)定載波(bo)(bo)電(dian)(dian)(dian)(dian)壓(ya)(ya)信(xin)號(hao)(hao)的(de)(de)(de)(de)(de)(de)(de)有(you)效(xiao)(xiao)值為(wei)110Vrms情況下(xia)，改變電(dian)(dian)(dian)(dian)壓(ya)(ya)信(xin)號(hao)(hao)的(de)(de)(de)(de)(de)(de)(de)頻率(lv)（f）進行(xing)測試，同(tong)樣使(shi)用周期為(wei)0.4ms的(de)(de)(de)(de)(de)(de)(de)方波(bo)(bo)調(diao)(diao)制(zhi)(zhi)信(xin)號(hao)(hao)對(dui)(dui)其(qi)進行(xing)振幅(fu)調(diao)(diao)制(zhi)(zhi)，調(diao)(diao)制(zhi)(zhi)深(shen)度也為(wei)100%，這樣獲得一個間斷(duan)的(de)(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)壓(ya)(ya)信(xin)號(hao)(hao)作用到ITO導(dao)電(dian)(dian)(dian)(dian)玻璃(li)上(shang)，測試電(dian)(dian)(dian)(dian)壓(ya)(ya)信(xin)號(hao)(hao)不(bu)同(tong)頻率(lv)下(xia)器(qi)件(jian)(jian)(jian)(jian)的(de)(de)(de)(de)(de)(de)(de)開關(guan)性能，圖2（b）顯示了所施加的(de)(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)壓(ya)(ya)信(xin)號(hao)(hao)示意(yi)圖以及(ji)不(bu)同(tong)電(dian)(dian)(dian)(dian)壓(ya)(ya)信(xin)號(hao)(hao)頻率(lv)下(xia)器(qi)件(jian)(jian)(jian)(jian)的(de)(de)(de)(de)(de)(de)(de)開關(guan)響(xiang)應(ying)結果(guo)，從圖中可以看到在1kHz時(shi)開關(guan)的(de)(de)(de)(de)(de)(de)(de)效(xiao)(xiao)率(lv)最高。綜上(shang)所述，對(dui)(dui)于所提出的(de)(de)(de)(de)(de)(de)(de)器(qi)件(jian)(jian)(jian)(jian)，在輸入(ru)光(guang)波(bo)(bo)長(chang)為(wei)1550nm時(shi)，使(shi)用有(you)效(xiao)(xiao)值為(wei)110Vrms且頻率(lv)為(wei)1kHz的(de)(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)壓(ya)(ya)信(xin)號(hao)(hao)可使(shi)器(qi)件(jian)(jian)(jian)(jian)獲得最好的(de)(de)(de)(de)(de)(de)(de)開關(guan)效(xiao)(xiao)果(guo)。

　　高壓放大器(qi)推薦：ATA-7015

　　圖：ATA-7015高壓放大器指標參數

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