LD泵浦3微米Er固體激光器輸出特性研究
發(fā)布時間：2018-10-14 21:00
【摘要】：2.5-3μm中紅外波段的激光在激光醫(yī)療技術(shù)、遙感技術(shù)、大氣環(huán)境監(jiān)測以及光電對抗等方面的應(yīng)用前景十分誘人,尤其是涉及被水強(qiáng)吸收和要求對生物組織穿透深度只有幾微米的方面。在高濃度摻Er情況下,Er激光介質(zhì)發(fā)射波長在3μm附近的波段內(nèi),恰好處于水的吸收峰附近。本文分析了Er激光介質(zhì)3μm附近波段的光譜,包括摻雜濃度為50at.%的Er:YAG晶體和摻雜濃度為10at.%的Er:YAG陶瓷。另外對摻雜濃度為30at.%的Er:YSGG晶體的光譜也做了簡單說明。在此基礎(chǔ)上,對LD端面泵浦的高摻Er:YAG晶體和陶瓷的輸出特性展開了研究。首先介紹了Er:YAG晶體的物理特性,之后簡單分析了Er3+的能級結(jié)構(gòu)。在此基礎(chǔ)上,對Er:YAG晶體的吸收光譜和熒光光譜進(jìn)行了計算,得出吸收截面和發(fā)射截面,進(jìn)一步計算還得到了增益截面和增益系數(shù)并對此進(jìn)行了分析。另外,利用J-O理論計算了Er:YAG晶體的光譜參數(shù),包括電偶極躍遷的振子強(qiáng)度,自發(fā)發(fā)射躍遷幾率,熒光壽命,躍遷熒光分支比以及積分發(fā)射截面等。對Er:YAG陶瓷的光譜進(jìn)行分析的方法與Er:YAG晶體類似。然后,以熱傳導(dǎo)方程為基礎(chǔ),建立了單端泵浦的柱狀熱分析模型,從理論上計算和模擬了Er:YAG晶體和Er:YAG陶瓷激光介質(zhì)內(nèi)的溫度分布,然后分析了它們的熱應(yīng)力和最大泵浦功率。最后,分析了Er3+的能級躍遷并討論了摻雜濃度對輸出波長的影響。在此基礎(chǔ)上,建立了包括速率方程在內(nèi)的Er:YAG固體激光器理論模型,進(jìn)一步討論了摻雜濃度的影響,并數(shù)值模擬了各種參數(shù)對Er:YAG固體激光器輸出的影響。在完成這些理論分析后,設(shè)計了諧振腔并進(jìn)行了初步實驗。通過對單摻Er激光介質(zhì)3μm波段光譜特性及輸出性能的研究,發(fā)現(xiàn)輸出較高功率、波長為2.94μm的激光所需要的條件是:較短的腔長、盡量低的腔內(nèi)損耗、高反射率的輸出鏡,另外還要設(shè)法減小激光介質(zhì)的熱效應(yīng)或增大激光介質(zhì)所能承受的最大應(yīng)力。同時,這些研究也為3μm波段相關(guān)激光器的研究提供了一定參考。
[Abstract]:2.5-3 渭 m mid-infrared laser has a very attractive prospect in laser medical technology, remote sensing technology, atmospheric environment monitoring and optoelectronic countermeasure, etc. In particular, it involves water absorption and requires a penetration depth of only a few microns to biological tissue. In the case of high concentration of Er doped, the emission wavelength of Er laser medium is about 3 渭 m, which is just near the absorption peak of water. In this paper, the spectra of Er laser medium near 3 渭 m are analyzed, including 50 at.% doped Er:YAG crystals and 10at.% doped Er:YAG ceramics. In addition, the spectra of Er:YSGG crystals with doping concentration of 30 at.% are also explained. On this basis, the output characteristics of highly doped Er:YAG crystals and ceramics pumped by LD are investigated. Firstly, the physical properties of Er:YAG crystal are introduced, and then the energy level structure of Er3 is analyzed briefly. On this basis, the absorption and fluorescence spectra of Er:YAG crystal are calculated, the absorption cross sections and emission cross sections are obtained, and the gain cross sections and gain coefficients are also calculated and analyzed. In addition, the spectral parameters of Er:YAG crystal are calculated by J-O theory, including the oscillator intensity of dipole transition, spontaneous emission transition probability, fluorescence lifetime, transition fluorescence branch ratio and integral emission cross section. The method of spectrum analysis of Er:YAG ceramics is similar to that of Er:YAG crystals. Then, based on the heat conduction equation, a single end pumped cylindrical thermal analysis model is established. The temperature distribution in Er:YAG crystal and Er:YAG ceramic laser medium is calculated and simulated theoretically, and their thermal stress and maximum pump power are analyzed. Finally, the energy level transition of Er3 is analyzed and the influence of doping concentration on the output wavelength is discussed. On this basis, the theoretical model of Er:YAG solid-state laser, including rate equation, is established. The influence of doping concentration on the output of Er:YAG solid-state laser is further discussed. The effects of various parameters on the output of Er:YAG solid-state laser are numerically simulated. After the theoretical analysis, the resonator is designed and a preliminary experiment is carried out. By studying the spectral characteristics and output performance of single doped Er laser dielectric at 3 渭 m band, it is found that the laser with high output power and wavelength of 2.94 渭 m requires the following conditions: shorter cavity length, lower intracavity loss, and higher reflectivity output mirror. In addition, it is necessary to reduce the thermal effect of the laser medium or to increase the maximum stress that the laser medium can withstand. At the same time, these studies also provide a certain reference for the study of 3 渭 m wavelength correlation lasers.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TN248.1
本文編號：2271630
[Abstract]:2.5-3 渭 m mid-infrared laser has a very attractive prospect in laser medical technology, remote sensing technology, atmospheric environment monitoring and optoelectronic countermeasure, etc. In particular, it involves water absorption and requires a penetration depth of only a few microns to biological tissue. In the case of high concentration of Er doped, the emission wavelength of Er laser medium is about 3 渭 m, which is just near the absorption peak of water. In this paper, the spectra of Er laser medium near 3 渭 m are analyzed, including 50 at.% doped Er:YAG crystals and 10at.% doped Er:YAG ceramics. In addition, the spectra of Er:YSGG crystals with doping concentration of 30 at.% are also explained. On this basis, the output characteristics of highly doped Er:YAG crystals and ceramics pumped by LD are investigated. Firstly, the physical properties of Er:YAG crystal are introduced, and then the energy level structure of Er3 is analyzed briefly. On this basis, the absorption and fluorescence spectra of Er:YAG crystal are calculated, the absorption cross sections and emission cross sections are obtained, and the gain cross sections and gain coefficients are also calculated and analyzed. In addition, the spectral parameters of Er:YAG crystal are calculated by J-O theory, including the oscillator intensity of dipole transition, spontaneous emission transition probability, fluorescence lifetime, transition fluorescence branch ratio and integral emission cross section. The method of spectrum analysis of Er:YAG ceramics is similar to that of Er:YAG crystals. Then, based on the heat conduction equation, a single end pumped cylindrical thermal analysis model is established. The temperature distribution in Er:YAG crystal and Er:YAG ceramic laser medium is calculated and simulated theoretically, and their thermal stress and maximum pump power are analyzed. Finally, the energy level transition of Er3 is analyzed and the influence of doping concentration on the output wavelength is discussed. On this basis, the theoretical model of Er:YAG solid-state laser, including rate equation, is established. The influence of doping concentration on the output of Er:YAG solid-state laser is further discussed. The effects of various parameters on the output of Er:YAG solid-state laser are numerically simulated. After the theoretical analysis, the resonator is designed and a preliminary experiment is carried out. By studying the spectral characteristics and output performance of single doped Er laser dielectric at 3 渭 m band, it is found that the laser with high output power and wavelength of 2.94 渭 m requires the following conditions: shorter cavity length, lower intracavity loss, and higher reflectivity output mirror. In addition, it is necessary to reduce the thermal effect of the laser medium or to increase the maximum stress that the laser medium can withstand. At the same time, these studies also provide a certain reference for the study of 3 渭 m wavelength correlation lasers.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TN248.1
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