【摘要】：超強(qiáng)超短脈沖經(jīng)過非線性介質(zhì)時呈現(xiàn)頻譜展寬的過程被稱為超連續(xù)光譜(Supercontinuum spectrum,SC)。該現(xiàn)象源于脈沖激光在非線性介質(zhì)中的自相位調(diào)制,交叉相位調(diào)制,受激拉曼散射和四波混頻等非線性效應(yīng)與光纖色散的共同作用導(dǎo)致超連續(xù)譜的展寬。中遠(yuǎn)紅外波段的超連續(xù)譜光源覆蓋了(2～16μm)分子指紋識別區(qū),包含兩個波段的大氣窗口,具備光譜范圍寬,相干性好等特點(diǎn),并廣泛應(yīng)用于熒光成像、全反射式熒光顯微系統(tǒng)(TIRF)、熒光壽命成像(FLIM)、光學(xué)相干層析術(shù)(OCT)、分子識別、紅外定向?qū)沟瓤茖W(xué)研究領(lǐng)域。硫系玻璃基質(zhì)材料具有極寬的中紅外透過光譜范圍(1～20μm),極高的折射率(2.0~3.5)和非線性系數(shù)n2,以及材料組分可調(diào)性等特性,使其在中遠(yuǎn)紅外超連續(xù)譜產(chǎn)生的非線性工作介質(zhì)中具有獨(dú)一無二的優(yōu)勢。傳統(tǒng)結(jié)構(gòu)的硫系光纖由于材料本身色散原因?qū)е铝闵Ⅻc(diǎn)(ZDW)普遍處于5μm以上中遠(yuǎn)紅外區(qū)域。由于光纖中的級聯(lián)SRS和SPM非線性效應(yīng)局限,用常規(guī)的1.5μm或2.0μm超短脈沖激光泵浦,難以取得平坦且寬的光譜輸出。光纖拉錐技術(shù)是一項(xiàng)重要的光纖后處理方法,硫系光纖經(jīng)過拉錐可靈便的調(diào)控光纖色散及非線性,有望完成全光纖中紅外超連續(xù)譜光源的研發(fā)。目前國際上報(bào)道的大多采用含As硫系玻璃(如As2S3或As2Se3)作為光纖基質(zhì)材料,這在光纖玻璃材料制備、拉絲以及后續(xù)的拉錐都是存在一定的安全隱患,同時含As的硫系玻璃其三階非線性型系數(shù)還有待提高。Ge-Sb-Se玻璃是一種環(huán)境友好型的新型硫系玻璃體系,具有較好的機(jī)械性能和紅外光學(xué)性能、較高的熱穩(wěn)定性、優(yōu)異的粘度和溫度特性。但目前為止,國際上很少有報(bào)道Ge-Sb-Se玻璃光纖拉錐制備及其紅外超連續(xù)譜輸出特性研究。本論文在拉錐硫系光纖的中紅外超連續(xù)譜研究的文獻(xiàn)調(diào)研基礎(chǔ)上,展開了Ge-Sb-Se拉錐光纖的制備,深入探索了硫系光纖拉錐工藝,并結(jié)合Rsoft光學(xué)軟件對Ge-Sb-Se硫系拉錐光纖群速色散進(jìn)行模擬計(jì)算分析,同時采用Mode Solutions光學(xué)軟件分析硫系拉錐光纖中過渡區(qū)域的光強(qiáng)變化及錐區(qū)能量傳輸?shù)男�。最后進(jìn)行飛秒激光泵浦Ge-Sb-Se硫系拉錐光纖,實(shí)現(xiàn)了中紅外超連續(xù)光譜輸出。
[Abstract]:The process of spectrum broadening of ultra-strong and ultra-short pulse passing through nonlinear medium is called supercontinuous spectrum (Supercontinuum spectrum,SC). This phenomenon is due to the broadening of supercontinuum caused by the nonlinear effects of pulse laser in nonlinear media, such as self-phase modulation, cross-phase modulation, stimulated Raman scattering and four-wave mixing, which lead to the broadening of supercontinuum spectrum. The supercontinuum light source in the middle and far infrared band covers the (2 ~ 16 渭 m) molecular fingerprint recognition region, contains two bands of atmospheric windows, has the characteristics of wide spectral range and good coherence, and is widely used in fluorescence imaging, total reflection fluorescence microscopic system (TIRF), fluorescence lifetime imaging (FLIM), optical coherence chromatography (OCT), molecular recognition, infrared directional confrontation and other scientific research fields. Sulfur glass matrix materials have a very wide range of mid-infrared transmission spectra (1 ~ 20 渭 m), very high refractive index (2.0 鈮，

本文編號：2503743