【摘要】：液芯光纖以其很小的彎曲半徑,良好的散熱性,很高的摻雜濃度,被廣泛應(yīng)用于通信,醫(yī)療和傳感等很多方面。近年來人們研究利用光子晶體光纖填充液體作為液芯光子晶體光纖的應(yīng)用成為研究的熱點(diǎn)。本文將利用光子晶體光纖填充溶液,研究光子晶體光纖的液體填充特性、填充制備、后端面處理和作為光纖鎖模器件在激光器中的應(yīng)用。本文主要研究工作圍繞著:理論上,分析了空芯光子晶體光纖和雙芯光纖填充的優(yōu)勢、填充溶液的方法。從原理方面對增益摻雜光子晶體光纖和鎖模啟動元件兩部分進(jìn)行了數(shù)學(xué)描述。其中對增益摻雜光子晶體光纖的描述包含其模式特性和傳輸特性兩個方面。為液芯光子晶體光纖作為光纖鎖模器件的理論和實(shí)驗(yàn)研究奠定了基礎(chǔ)。首次提出把雙液芯光子晶體光纖作為鎖模啟動元件的鎖模激光器,進(jìn)行了仿真模擬,基于雙芯光子晶體光纖的非線性耦合特性,得到了輸出脈沖的壓縮。實(shí)現(xiàn)了在低功率下,從一個纖芯入射的功率在耦合作用下經(jīng)過一個耦合長度后從相鄰的纖芯輸出;在高功率下,由于非線性作用改變了入射光纖的折射率,纖芯之間的相位失配增加,從一個纖芯入射的功率保持在這個纖芯中傳輸,滿足可飽和吸收作用。仿真設(shè)計(jì)了腔型結(jié)構(gòu),把雙液芯光子晶體光纖作為可飽和吸收體,模擬腔內(nèi)動力學(xué)過程,得到穩(wěn)定的鎖模輸出。分析研究了雙芯光子晶體光纖非線性模式耦合和光纖長度對鎖模的影響,得到了光纖長度與線性耦合長度不是整數(shù)倍,實(shí)現(xiàn)自啟動和穩(wěn)定的鎖模,當(dāng)光纖長度遠(yuǎn)大于線性耦合長度時,需要濾波器來穩(wěn)定鎖模運(yùn)轉(zhuǎn)。實(shí)驗(yàn)上,利用普通熔接機(jī)放電對光纖塌陷進(jìn)行選擇性填充,通過不同光子晶體光纖之間的塌陷對比得到放電塌陷參數(shù),并對空芯光子晶體光纖和雙芯光子晶體光纖進(jìn)行了選擇性填。利用虹吸法填充溶液,截?cái)喾ㄓ^測纖芯液體填充是否均勻,最后對光纖端面進(jìn)行后處理,如對填充后的光纖進(jìn)行塌陷、研磨等,這大大增加了光纖端面的平整度,提高了耦合效率和出射光斑質(zhì)量。為了對制備的液芯光子晶體光纖器件進(jìn)行驗(yàn)證,把制備的液芯光纖進(jìn)行空間光耦合輸出,得到了很好光斑質(zhì)量輸出。綜上,在理論和實(shí)驗(yàn)研究的基礎(chǔ)上,有望進(jìn)一步把制備的液芯光子晶體光纖作為光纖器件運(yùn)用到探索可見光波段的放大器和振蕩器,并得到光波段的拓展及鎖模器件的廣泛應(yīng)用。
[Abstract]:Liquid core fiber has been widely used in many fields such as communication, medical treatment and sensing because of its small bending radius, good heat dissipation and high doping concentration. In recent years, the application of photonic crystal fiber filled liquid as liquid core photonic crystal fiber has become a hot topic. In this paper, the liquid filling characteristics of photonic crystal fiber (PCF), its preparation, back-end surface treatment and its application as fiber mode-locking devices are studied by using photonic crystal fiber filling solution. This paper focuses on: theoretically, the advantages of empty-core photonic crystal fiber and double-core fiber filling and the method of filling solution are analyzed. Two parts of gain doped photonic crystal fiber and mode-locked starter are described mathematically in principle. The description of gain doped photonic crystal fiber includes two aspects: mode characteristic and transmission characteristic. It lays a foundation for the theoretical and experimental study of liquid core photonic crystal fiber as an optical fiber mode-locking device. A mode-locked laser using dual-liquid core photonic crystal fiber as the mode-locking starting element is proposed for the first time. The output pulse compression is obtained based on the nonlinear coupling characteristics of the two-core photonic crystal fiber. Under low power, the incident power from one fiber core passes through a coupling length and then outputs from the adjacent core. At high power, the refractive index of the incident fiber is changed due to the nonlinear effect, and the phase mismatch between the cores increases. The incident power from one core is kept in the core to satisfy the saturable absorption effect. The cavity structure is simulated and the two-core photonic crystal fiber is used as the saturable absorber to simulate the dynamic process in the cavity and obtain a stable mode-locked output. The effects of nonlinear mode coupling and fiber length on mode-locking of two-core photonic crystal fiber are analyzed and studied. It is concluded that the length of fiber and linear coupling length are not integer times, so the self-starting and stable mode-locking can be realized. When the fiber length is much longer than the linear coupling length, a filter is needed to stabilize the mode-locked operation. In the experiment, the conventional welding machine is used to fill the fiber collapse selectively, and the discharge collapse parameters are obtained by comparing the collapse of different photonic crystal fibers. The empty core photonic crystal fiber and two core photonic crystal fiber were filled selectively. The siphon method is used to fill the solution, the truncation method is used to observe the uniformity of the liquid filling of the fiber core. Finally, the end surface of the fiber is post-treated, such as the collapse and grinding of the filled fiber, which greatly increases the smoothness of the fiber end surface. The coupling efficiency and the quality of the speckle are improved. In order to verify the fabricated liquid-core photonic crystal fiber devices, the liquid-core optical fiber is output by spatial light coupling, and a good light spot quality output is obtained. In summary, on the basis of theoretical and experimental research, it is expected that the liquid-core photonic crystal fiber will be further used as an optical fiber device to explore the visible light band amplifiers and oscillators. The expansion of optical wave band and the wide application of mode-locked devices are obtained.
【學(xué)位授予單位】：北京工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TN253
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本文編號：2343549