實驗名稱：鎖相(xiang)環穩定重復頻率(lv)的系(xi)統(tong)分(fen)析

　　實驗內容：針對重復(fu)頻(pin)率(lv)的(de)漂移，引入兩套鎖(suo)相(xiang)(xiang)環(huan)(huan)系統反饋控(kong)制(zhi)兩個(ge)激光器(qi)的(de)重復(fu)頻(pin)率(lv)，將(jiang)其鎖(suo)定(ding)(ding)在(zai)同一個(ge)穩定(ding)(ding)的(de)時(shi)鐘源(yuan)上。本(ben)章主要闡述了經典鎖(suo)相(xiang)(xiang)環(huan)(huan)的(de)原理，穩定(ding)(ding)重復(fu)頻(pin)率(lv)的(de)鎖(suo)相(xiang)(xiang)環(huan)(huan)理論和關(guan)鍵器(qi)件，以(yi)及結(jie)果分析。

　　測試設備：高壓放大器(qi)、光電探測器(qi)、低通濾波器(qi)、比例積分(fen)控制器(qi)、PZT等。

　　圖1：穩定重復(fu)頻率的鎖相環系統結構圖

　　實驗過程：

　　系統(tong)(tong)結構(gou)圖如圖1所(suo)示，從NPR鎖模光(guang)(guang)(guang)纖(xian)激(ji)(ji)(ji)光(guang)(guang)(guang)器(qi)(qi)(qi)(qi)(qi)耦合出(chu)一(yi)部分光(guang)(guang)(guang)進入(ru)(ru)光(guang)(guang)(guang)電(dian)(dian)探測器(qi)(qi)(qi)(qi)(qi)，其帶寬(kuan)為(wei)(wei)5GHz，將(jiang)光(guang)(guang)(guang)信(xin)(xin)(xin)號(hao)轉化(hua)為(wei)(wei)電(dian)(dian)信(xin)(xin)(xin)號(hao)，同(tong)(tong)(tong)時(shi)(shi)(shi)提取出(chu)重(zhong)(zhong)復(fu)(fu)(fu)(fu)頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)率。該電(dian)(dian)信(xin)(xin)(xin)號(hao)隔直流（DCBlock）之(zhi)(zhi)后(hou)與(yu)(yu)(yu)一(yi)個穩(wen)定(ding)的(de)(de)(de)時(shi)(shi)(shi)鐘(zhong)源(yuan)(yuan)輸出(chu)的(de)(de)(de)射(she)頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)信(xin)(xin)(xin)號(hao)同(tong)(tong)(tong)時(shi)(shi)(shi)進入(ru)(ru)混(hun)頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)器(qi)(qi)(qi)(qi)(qi)，即鑒相(xiang)器(qi)(qi)(qi)(qi)(qi)，重(zhong)(zhong)復(fu)(fu)(fu)(fu)頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)率與(yu)(yu)(yu)時(shi)(shi)(shi)鐘(zhong)源(yuan)(yuan)輸出(chu)的(de)(de)(de)射(she)頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)信(xin)(xin)(xin)號(hao)混(hun)頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)，得到(dao)差(cha)頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)信(xin)(xin)(xin)號(hao)與(yu)(yu)(yu)和(he)(he)頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)信(xin)(xin)(xin)號(hao)，差(cha)頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)信(xin)(xin)(xin)號(hao)是(shi)所(suo)需要的(de)(de)(de)誤(wu)差(cha)信(xin)(xin)(xin)號(hao)，經過(guo)低通濾(lv)波(bo)器(qi)(qi)(qi)(qi)(qi)（LPF）濾(lv)除和(he)(he)頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)信(xin)(xin)(xin)號(hao)，差(cha)頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)信(xin)(xin)(xin)號(hao)進入(ru)(ru)比例積分（PI）控制(zhi)器(qi)(qi)(qi)(qi)(qi)，這里LPF和(he)(he)PI控制(zhi)器(qi)(qi)(qi)(qi)(qi)共(gong)同(tong)(tong)(tong)組成鎖相(xiang)環(huan)(huan)的(de)(de)(de)環(huan)(huan)路濾(lv)波(bo)器(qi)(qi)(qi)(qi)(qi)，PI控制(zhi)器(qi)(qi)(qi)(qi)(qi)輸出(chu)后(hou)的(de)(de)(de)誤(wu)差(cha)電(dian)(dian)壓(ya)信(xin)(xin)(xin)號(hao)其范(fan)圍為(wei)(wei)–10V~+10V，不足以驅(qu)動(dong)壓(ya)電(dian)(dian)陶瓷（PZT），先進入(ru)(ru)高(gao)壓(ya)放大(da)器(qi)(qi)(qi)(qi)(qi)（HVAMP）放大(da)十倍后(hou)施(shi)加給(gei)PZT，不同(tong)(tong)(tong)的(de)(de)(de)電(dian)(dian)壓(ya)值引起PZT的(de)(de)(de)伸縮(suo)量不同(tong)(tong)(tong)，基本呈現(xian)線性(xing)關系。PZT在光(guang)(guang)(guang)纖(xian)形(xing)成的(de)(de)(de)激(ji)(ji)(ji)光(guang)(guang)(guang)器(qi)(qi)(qi)(qi)(qi)腔(qiang)(qiang)(qiang)(qiang)中無法直接改變(bian)腔(qiang)(qiang)(qiang)(qiang)長(chang)，借助(zhu)平移臺(tai)，PZT驅(qu)動(dong)平移臺(tai)移動(dong)，并且(qie)(qie)將(jiang)光(guang)(guang)(guang)纖(xian)腔(qiang)(qiang)(qiang)(qiang)繞在平移臺(tai)上，從而實現(xian)PZT的(de)(de)(de)伸縮(suo)引起腔(qiang)(qiang)(qiang)(qiang)長(chang)的(de)(de)(de)變(bian)化(hua)來調節激(ji)(ji)(ji)光(guang)(guang)(guang)器(qi)(qi)(qi)(qi)(qi)重(zhong)(zhong)復(fu)(fu)(fu)(fu)頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)率，形(xing)成了重(zhong)(zhong)復(fu)(fu)(fu)(fu)頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)率跟蹤(zong)時(shi)(shi)(shi)鐘(zhong)源(yuan)(yuan)射(she)頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)信(xin)(xin)(xin)號(hao)的(de)(de)(de)閉(bi)環(huan)(huan)電(dian)(dian)路。當激(ji)(ji)(ji)光(guang)(guang)(guang)器(qi)(qi)(qi)(qi)(qi)的(de)(de)(de)重(zhong)(zhong)復(fu)(fu)(fu)(fu)頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)率和(he)(he)時(shi)(shi)(shi)鐘(zhong)源(yuan)(yuan)的(de)(de)(de)參考頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)率一(yi)致時(shi)(shi)(shi)，誤(wu)差(cha)電(dian)(dian)壓(ya)變(bian)為(wei)(wei)一(yi)個直流量，PZT狀態穩(wen)定(ding)，激(ji)(ji)(ji)光(guang)(guang)(guang)器(qi)(qi)(qi)(qi)(qi)的(de)(de)(de)重(zhong)(zhong)復(fu)(fu)(fu)(fu)頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)率穩(wen)定(ding)在時(shi)(shi)(shi)鐘(zhong)源(yuan)(yuan)的(de)(de)(de)參考頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)率上。一(yi)旦外界環(huan)(huan)境(jing)對(dui)激(ji)(ji)(ji)光(guang)(guang)(guang)器(qi)(qi)(qi)(qi)(qi)腔(qiang)(qiang)(qiang)(qiang)出(chu)現(xian)干(gan)擾(rao)，打破(po)穩(wen)定(ding)狀態，誤(wu)差(cha)電(dian)(dian)壓(ya)信(xin)(xin)(xin)號(hao)出(chu)現(xian)抖動(dong)反饋再次起作用，調節腔(qiang)(qiang)(qiang)(qiang)長(chang)使(shi)得重(zhong)(zhong)復(fu)(fu)(fu)(fu)頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)率快速恢復(fu)(fu)(fu)(fu)穩(wen)定(ding)。當建立(li)一(yi)套(tao)穩(wen)定(ding)第(di)一(yi)個鎖模激(ji)(ji)(ji)光(guang)(guang)(guang)器(qi)(qi)(qi)(qi)(qi)重(zhong)(zhong)復(fu)(fu)(fu)(fu)頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)率的(de)(de)(de)鎖相(xiang)環(huan)(huan)系統(tong)(tong)之(zhi)(zhi)后(hou)，重(zhong)(zhong)復(fu)(fu)(fu)(fu)整個鎖相(xiang)環(huan)(huan)系統(tong)(tong)鎖定(ding)第(di)二個鎖模激(ji)(ji)(ji)光(guang)(guang)(guang)器(qi)(qi)(qi)(qi)(qi)的(de)(de)(de)重(zhong)(zhong)復(fu)(fu)(fu)(fu)頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)率，并且(qie)(qie)其使(shi)用的(de)(de)(de)參考頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)率是(shi)由(you)同(tong)(tong)(tong)一(yi)個時(shi)(shi)(shi)鐘(zhong)源(yuan)(yuan)產(chan)生，保證了兩個激(ji)(ji)(ji)光(guang)(guang)(guang)器(qi)(qi)(qi)(qi)(qi)其重(zhong)(zhong)復(fu)(fu)(fu)(fu)頻(pin)(pin)(pin)(pin)(pin)(pin)(pin)(pin)率之(zhi)(zhi)間的(de)(de)(de)相(xiang)對(dui)穩(wen)定(ding)性(xing)。

　　實驗結果：

　　圖2：鎖相環(huan)中間鏈(lian)路各點(dian)時域波(bo)形

　　成功搭建(jian)鎖(suo)(suo)相環(huan)(huan)之后(hou)，對鎖(suo)(suo)相環(huan)(huan)的中(zhong)間鏈路點進(jin)行了(le)測試。圖(tu)2(a)表(biao)示(shi)(shi)了(le)重(zhong)復頻(pin)率(lv)與時鐘(zhong)源的參考頻(pin)率(lv)混頻(pin)后(hou)的誤差(cha)(cha)電壓(ya)信(xin)號(hao)，從圖(tu)中(zhong)可以看到(dao)包絡下(xia)仍(reng)有振蕩(dang)紋(wen)，說明既有差(cha)(cha)頻(pin)信(xin)號(hao)，也(ye)包含了(le)和頻(pin)信(xin)號(hao)。圖(tu)2(b)表(biao)示(shi)(shi)誤差(cha)(cha)電壓(ya)信(xin)號(hao)經過(guo)低通濾(lv)波器(qi)后(hou)的波形，濾(lv)取(qu)出了(le)差(cha)(cha)頻(pin)。圖(tu)2(c)表(biao)示(shi)(shi)了(le)經過(guo)PI控制器(qi)的作用后(hou)的誤差(cha)(cha)電壓(ya)信(xin)號(hao)，圖(tu)2(d)表(biao)示(shi)(shi)達到(dao)穩(wen)定狀態后(hou)的誤差(cha)(cha)電壓(ya)信(xin)號(hao)變為直(zhi)流(liu)。

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