本文選題：諧振式光纖陀螺 + 相位調(diào)制技術(shù)�。� 參考：《浙江大學》2016年博士論文

【摘要】：陀螺儀是用于測量載體旋轉(zhuǎn)角速度的一種慣性傳感器�；赟agnac效應(yīng)的光纖陀螺具有全固態(tài)結(jié)構(gòu),抗震動沖擊、靈敏度高、動態(tài)范圍大的優(yōu)點。諧振式光纖陀螺(Resonantor Fiber Optic Gyroscope, RFOG)以光纖諧振腔為核心敏感元件,利用光在諧振腔內(nèi)多次傳輸增強Sagnac效應(yīng),和成熟的干涉式光纖陀螺相比,RFOG利用較短的敏感光纖就能實現(xiàn)較高的檢測精度,在小型化和集成化上具有明顯優(yōu)勢。針對長期制約RFOG穩(wěn)定性提高的偏振波動噪聲,論文采用特殊光纖包括單偏振光纖(Single-Polarization Fiber, SPF)和保偏空芯光子晶體帶隙光纖(Hollow-Core Photonic Bandgap Fiber, HC-PBF)研制諧振腔,利用瓊斯矩陣方法建立了SPF混合諧振腔偏振特性分析模型,優(yōu)化設(shè)計了混合諧振腔結(jié)構(gòu),提高了偏振波動噪聲抑制效果；在保偏HC-PBF混合諧振腔中,則著重分析了諧振腔內(nèi)兩種不同光纖端面強反射特性對RFOG輸出波動的影響。具體來說,論文的主要創(chuàng)新工作包括如下三個方面：(1)正弦相位調(diào)制技術(shù)被廣泛應(yīng)用于RFOG,論文著重對施加在相位調(diào)制器上的正弦信號調(diào)制頻率進行了優(yōu)化。針對兩種不同結(jié)構(gòu)的光纖諧振腔(反射式和透射式),利用數(shù)學推導得到了諧振點處解調(diào)曲線斜率的解析表達式；繪制了解調(diào)斜率和調(diào)制頻率之間的關(guān)系曲線,得到了最大解調(diào)斜率所對應(yīng)的最佳調(diào)制頻率,相比于原有采用洛倫茲近似得到的最佳調(diào)制頻率,優(yōu)化后的調(diào)制頻率能夠?qū)⒔庹{(diào)曲線斜率提高近1倍；搭建了實際RFOG系統(tǒng),對上述仿真結(jié)果進行了具體的實驗驗證。(2)為了在更大溫度范圍內(nèi)減小偏振波動對RFOG檢測精度的影響,論文提出了一種基于普通保偏光纖耦合器和SPF構(gòu)成的混合諧振腔技術(shù)�；诃偹咕仃嚨姆椒�,計算分析了各種不同諧振腔中的偏振波動噪聲,研究發(fā)現(xiàn),2次90°偏振軸旋轉(zhuǎn)熔接的全對稱混合諧振腔,在相同器件參數(shù)條件下,偏振波動影響最��；兼顧清晰度和諧振峰值兩個指標,優(yōu)化設(shè)計了諧振腔結(jié)構(gòu)參數(shù),諧振腔測試清晰度為14.7,1.3 mW入腔功率下,RFOG理論靈敏度為0.32°/h；仿真結(jié)果顯示,100℃的溫度波動,帶來的偏振噪聲約0.29°/h,相比于課題組前期提出的2次900偏振軸旋轉(zhuǎn)熔接的起偏腔,偏振波動噪聲降低了29倍；將上述全對稱SPF混合諧振腔應(yīng)用于實際RFOG系統(tǒng),測試到的陀螺最小擺動信號為±0.001°/s,1200s測試時間,零偏穩(wěn)定性為0.3°/h,隨機游走系數(shù)為0.08°/(?)；進一步的溫度特性測試表明,20分鐘時間,當諧振腔溫度從15-C變化到27-C時,RFOG輸出偏置保持穩(wěn)定。(3)為了從誤差產(chǎn)生根源上減小三大光學噪聲影響,論文采用一個普通保偏光纖耦合器和一段長約10米的保偏HC-PBF直接熔接,構(gòu)成了一個反射式HC-PBF混合諧振腔。兼顧清晰度和諧振深度兩個指標,優(yōu)化設(shè)計了HC-PBF混合諧振腔,測試清晰度和諧振深度分別為6.67和0.3246；利用傳遞函數(shù)的方法,對混合諧振腔內(nèi)的兩種不同光纖熔接點處的端面反射特性進行了建模分析和實驗測試,研究發(fā)現(xiàn),混合諧振腔內(nèi)奇數(shù)次背向反射噪聲和普通保偏光纖諧振腔中的瑞利背散射噪聲影響類似,可以用載波抑制方法得到減小,然而偶數(shù)次反射光波和原信號光疊加在一起,影響了此種陀螺的短期精度；將HC-PBF混合諧振腔應(yīng)用于實際RFOG,1小時測試時間,1s積分時間下,輸出波動峰峰值為0.344°/s,和其100s的短期測試結(jié)果0.3°/s相接近。由此可知,目前采用HC-PBF混合諧振腔作為核心敏感元件的RFOG,其檢測精度主要受限于短期噪聲影響,對RFOG輸出結(jié)果作Allan方差分析,零偏穩(wěn)定性為0.007°/s�？傊�,在缺少成熟的低損耗SPF以及HC-PBF耦合器的情況下,論文采用普通保偏光纖耦合器和SPF、HC-PBF直接熔接的方法研制諧振腔。初步研究表明,研制的SPF混合諧振腔,在更大溫度波動范圍內(nèi),表現(xiàn)出了較好的偏振穩(wěn)定性；基于HC-PBF諧振腔上得到0.007°/s的零偏穩(wěn)定性,則是同類研究中得到的最好的陀螺測試結(jié)果。
[Abstract]:The optical fiber gyroscope based on Sagnac effect has the advantages of full solid structure , anti - vibration shock , high sensitivity and large dynamic range .
In the polarization - maintaining HC - PBF hybrid resonant cavity , the influence of the strong reflection characteristics of two different fiber end faces in the resonant cavity on the output fluctuation of the RGs is emphatically analyzed . In particular , the main innovations of the thesis include the following three aspects : ( 1 ) the sinusoidal phase modulation technique is widely used in the RGs , the paper mainly focuses on the optimization of the sinusoidal signal modulation frequency applied to the phase modulator . According to the two different structures of the optical fiber resonant cavity ( reflective and transmissive ) , the analytical expression of the slope of the demodulation curve at the resonance point is obtained by mathematical derivation ;
The best modulation frequency corresponding to the maximum demodulation slope is obtained by drawing the relation curve between the modulation slope and the modulation frequency , and the optimized modulation frequency can increase the slope of the demodulation curve by nearly 1 times compared with the original optimal modulation frequency obtained by using the Lorentz approximation ;
( 2 ) In order to reduce the influence of polarization fluctuation on the accuracy of RGs detection in a wider temperature range , a hybrid resonant cavity based on common polarization maintaining fiber coupler and SPF is presented . Based on Jones matrix , the polarization fluctuation noise in various resonant cavities is calculated and analyzed .
According to both the definition and the resonance peak , the resonator structure parameters are optimized . The resonant cavity test clarity is 14.7 and 1.3 mW input cavity power , and the theoretical sensitivity of the RGs is 0.32 擄 / h ;
The simulation results show that the polarization noise caused by the temperature fluctuation of 100 鈩，

本文編號：2014531