本文選題：部分相干光　切入點：相位調制　出處：《西安電子科技大學》2014年碩士論文

【摘要】：相干光在傳輸過程中受大氣的影響退化為部分相干光;同時部分相干光的大氣傳輸特性可以有效抑制湍流帶來的光強閃爍、相位起伏等影響。近幾年激光雷達研究的熱點之一的新體制激光符合成像雷達,正是要用具有部分相干光特性的激光作為發(fā)射光源。因此,研究部分相干光的產(chǎn)生方法是很必要的。采用激光照射到旋轉毛玻璃形成的動態(tài)散斑作為部分相干光源是如今最常用的產(chǎn)生方法,可行性高且系統(tǒng)成本較低,但毛玻璃的存在會大大降低激光輸出功率;激光器諧振腔內調制產(chǎn)生部分相干光的系統(tǒng)較為復雜,且成本相對較高;基于液晶空間光調制器的部分相干光方案也受限于輸出功率和調制速度等因素。因此開展可產(chǎn)生高功率輸出、相干性可控和可快速預置光場的部分相干光的研究,具有重要的學術意義和應用價值。本文基于陣列光束合成和部分相干光理論,從理論和實驗的角度分別對光纖陣列產(chǎn)生部分相干光系統(tǒng)的方案進行驗證。首先介紹了光的相干性理論,然后分別闡述了光的時間相干性,空間相干性和部分相干性。介紹了一種典型部分相干光的數(shù)學模型,并從關聯(lián)性角度來描述其光場的相干性,簡單描述了光場的高階相關理論,并通過光的強度關聯(lián)系數(shù)來為后續(xù)測試部分相干光相干長度做出理論鋪墊。基于光束合成理論,研究了不同模型,不同間距,不同附加隨機相位抖動方差下的光場強度分布的數(shù)值仿真,為后續(xù)實驗系統(tǒng)改進和實驗測試提供理論依據(jù)。利用鈮酸鋰相位型調制器、平面波導(PLC)光纖分路器和光纖陣列基板(FA)設計和改進了實驗室搭建的部分相干光的方案。采用實驗室開發(fā)的基于FPGA的相位調制器驅動電路可為相位調制器提供最高10MHz,±5V的模擬電壓輸出。利用光纖陣列部分相干光產(chǎn)生系統(tǒng)對部分相干合成后的光強分布與空間相干性進行了實驗測試,通過驅動電路系統(tǒng)加載不同范圍均勻隨機電壓,可使強度關聯(lián)系數(shù)在1~1.48范圍內可控。通過實驗結果測試與理論仿真對比,驗證了方案可行性。
[Abstract]:The atmospheric effect of coherent light is reduced to partially coherent light, and the atmospheric propagation characteristics of partially coherent light can effectively suppress the effects of turbulence, such as intensity scintillation and phase fluctuation.In recent years, one of the hotspots of lidar, laser coincidence imaging radar, is to use laser with partial coherent light as the emitting light source.Therefore, it is necessary to study the generation method of partially coherent light.The dynamic speckle produced by laser irradiation to the rotating glass is the most commonly used generation method nowadays, which has high feasibility and low system cost, but the laser output power will be greatly reduced by the existence of the ground glass.The system of laser resonator modulation to produce partially coherent light is complex and the cost is relatively high. The partially coherent light scheme based on liquid crystal spatial light modulator is also limited by the output power and modulation speed.Therefore, the research of partially coherent light which can produce high power output, coherence controllable and fast preset light field has important academic significance and application value.Based on the theory of array beam synthesis and partially coherent light, the scheme of optical fiber array generating partially coherent optical system is verified theoretically and experimentally in this paper.Firstly, the coherence theory of light is introduced, and then the temporal coherence, spatial coherence and partial coherence of light are described respectively.In this paper, a mathematical model of a typical partially coherent light is introduced, and the coherence of the light field is described from the angle of correlation, and the high order correlation theory of the light field is briefly described.The correlation coefficient of light intensity is used to lay a theoretical foundation for the subsequent measurement of coherent length of partially coherent light.Based on the theory of beam synthesis, the numerical simulation of intensity distribution of light field with different models, different spacing and different variance of additional random phase jitter is studied, which provides a theoretical basis for the improvement of the experimental system and the experimental test.Using lithium niobate phase modulator, planar waveguide PLC fiber splitter and fiber array substrate FAA), the scheme of partially coherent light in laboratory is designed and improved.The phase modulator drive circuit based on FPGA developed in laboratory can provide the analog voltage output of up to 10 MHz and 鹵5 V for the phase modulator.The optical intensity distribution and spatial coherence after partial coherent combination are experimentally tested using partially coherent optical fiber array optical generation system. The uniform random voltages with different ranges are loaded through the drive circuit system.The strength correlation coefficient can be controlled in the range of 1 ~ 1.48.The feasibility of the scheme is verified by comparing the experimental results with the theoretical simulation.
【學位授予單位】：西安電子科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN958.98

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相關期刊論文 前1條

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本文編號：1724388