【摘要】：在超高速超大容量光纖通信系統(tǒng)中,隨著對色散和衰減的逐步解決,光纖的非線性成為影響信號傳輸質(zhì)量的重要因素。光纖的非線性由光纖的光學(xué)參數(shù)和幾何參數(shù)共同決定,因此可通過優(yōu)化設(shè)計(jì)光纖以調(diào)整其非線性,使其更高效地服務(wù)于新一代光纖通信系統(tǒng)或光器件設(shè)計(jì)。本文利用光波導(dǎo)理論,運(yùn)用全矢量法模擬分析了單軸晶體包層光纖基模的有效模場面積和非線性系數(shù),并進(jìn)行數(shù)值求解,獲得了如下結(jié)論:1.單軸晶體包層主折射率比kcl對光纖的模場分布有影響,光纖的有效模場面積隨著kcl的減小而增大,在λ1.3μm時,負(fù)單軸晶體(kcl1)包層光纖具有比傳統(tǒng)光纖更大的模場面積和更低的光功率密度。2.在波長λ1.3μm的范圍,單軸晶體包層光纖的主折射率比越小,其非線性系數(shù)就越小,表明采用負(fù)單軸晶體材料作為包層將能更充分地抑制該種光纖在通信過程中產(chǎn)生的非線性效應(yīng);而采用正單軸晶體材料作為包層將使得該種光纖表現(xiàn)出更強(qiáng)烈的非線性效應(yīng),該結(jié)論為非線性光纖通信器件和非線性光纖傳感器的設(shè)計(jì)提供理論基礎(chǔ)。3.一定入射波長下,如λ=1.55μm,在改變主折射率比的同時分別改變光纖半徑、纖芯折射率、包層-纖芯折射率差,發(fā)現(xiàn)該種光纖的非線性系數(shù)有著不同的變化特性,表明同時改變光纖參數(shù)以及主折射率比可優(yōu)化設(shè)計(jì)該種光纖的非線性系數(shù)。4.分別采用負(fù)單軸電光晶體鈮酸鋰(LiNbO3)和彈光晶體磷酸二氫鉀(KDP)作為光纖的包層時,利用LiNbO3晶體的電光效應(yīng)或KDP晶體的彈光效應(yīng),通過施加外電場或應(yīng)變場可實(shí)現(xiàn)非線性系數(shù)的連續(xù)可調(diào)。
[Abstract]:In ultra-high speed and super-large capacity optical fiber communication system, with the gradual solution of dispersion and attenuation, the nonlinearity of optical fiber becomes an important factor affecting the quality of signal transmission. The nonlinearity of the fiber is determined by the optical parameters and geometric parameters of the fiber, so the nonlinear of the fiber can be adjusted by optimizing the design of the fiber, so that it can serve the design of the next generation optical fiber communication system or optical device more efficiently. In this paper, the effective mode area and the nonlinear coefficient of the fundamental mode of uniaxial crystal clad fiber are simulated and analyzed by using the optical waveguide theory and the full vector method. The numerical results are obtained as follows: 1. The main refractive index ratio of uniaxial crystal cladding has an effect on the mode field distribution of the fiber. The effective mode field area of the fiber increases with the decrease of kcl. At 位 1.3 渭 m, the effective mode field area of the fiber increases with the decrease of kcl. Negative uniaxial crystal (kcl1) clad fiber has larger mode field area and lower optical power density than traditional fiber. 2. In the wavelength range of 位 1.3 渭 m, the smaller the principal refractive index ratio of uniaxial crystal clad fiber is, the smaller the nonlinear coefficient is. It is shown that using negative uniaxial crystal material as cladding can restrain the nonlinear effect of this kind of fiber in the communication process more fully. The positive uniaxial crystal material as cladding will make the fiber show stronger nonlinear effect. The conclusion provides a theoretical basis for the design of nonlinear optical fiber communication devices and nonlinear optical fiber sensors. 3. At a certain incident wavelength, such as 位 = 1.55 渭 m, the fiber radius, core refractive index and cladding-core refractive index difference are changed at the same time of changing the principal refractive index ratio. It is found that the nonlinear coefficient of this kind of fiber has different variation characteristics. It is shown that the nonlinear coefficient of the fiber can be optimized by changing the parameters of the fiber and the principal refractive index ratio at the same time. 4. When negative uniaxial electro-optic crystal lithium niobate (LiNbO3) and elasto-optical crystal potassium dihydrogen phosphate (KDP) are used as cladding layer of optical fiber, the electro-optic effect of LiNbO3 crystal or elasto-optical effect of KDP crystal are used. The continuous adjustment of nonlinear coefficient can be achieved by applying external electric field or strain field.
【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TN253

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本文編號：2466878