立方晶体非线性折射系数的各向异性

本文分析了立方晶体三次非线性极化强度P~((3))的各向异性,导出了非线性折射系数各向异性的一般表达式,讨论了强光束在立方晶体中的自感生偏振变化规律.     

The nonlinear refractive index of glass

The general theory of the third-order electronic susceptibility has been specialized to some model systems in order to evaluate the associated nonlinear refractive index of solid materials. The results indicate oppositely signed terms of comparable magnitude, and it is found that the dominant positive contribution involves oscillator strengths connecting excited electronic levels. Some reported values of the nonlinear index n2for various glasses are discussed in relation to the model calculations.     

室温350~850 nm ZnSe晶体生长及阴极荧光光谱图谱分析

室温下利用阴极荧光光谱技术对ZnSe晶体进行了350~850 nm的无损全光阴极荧光图谱检测,分析了晶体内部缺陷及夹杂情况,室温下测得ZnSe晶体在400~550 nm的阴极荧光光谱,阴极荧光光谱测得462 nm处的ZnSe本征发光峰。缺陷处测得462 nm的本征发光峰和453 nm的缺陷发光峰,结合能谱分析,ZnSe晶体表面缺陷处的Zn：Se比约为6：4。阴极荧光图谱中缺陷处发光峰主要来自Zn夹杂缺陷发光。     

Investigation on refractive index sensing of single silver nanoparticle at tightly focused light illumination

Based on the generalized Mie theory, refractive index sensing characteristics of single silver nanoparticle respectively illuminated by tightly focused linearly-polarized and radially-polarized light beams are investigated. The spectra for localized surface plasmon resonances (LSPR) under different dielectric environments demonstrate that distinct dipolar and quadrupolar resonances can be always observed for the case of radial polarization, while there is only strong dipolar resonance for the case of linear polarization. The dipolar mode has a higher sensitivity. However, the figure of merit (FOM) for the quadrupolar resonance is much higher than that for the dipolar resonance, because the quadrupolar resonance has a narrower width.     

负折射率柱形光子晶体的全反射隧穿特性

为了研究一维含负折射率柱形光子晶体的全反射隧穿效应,利用特征矩阵法研究了光波在大于全反射角入射一维含负折射率柱形光子晶体时所产生的全反射隧穿教应。得出了基全反射隧穿峰的频率随周期数、模式量子数以及圆柱半径的变化特性。     

含梯度折射率缺陷的一维光子晶体滤波性能研究

为实现一维光子晶体更优越的滤波特性,引入渐变折射率缺陷层,可以抑制某些特定频率的电磁波,产生光子禁带。利用时域有限差分（FDTD）法,严格求解麦克斯韦方程组。研究了缺陷层的折射率变化为抛物线型时对应的透射率谱线,并分析了周期介质层的折射率比、厚度比及周期数,对滤波性能的影响。研究表明,增加折射率比,含梯度折射率缺陷层的一维光子晶体可以实现更大的滤波带宽;改变厚度比,可以影响透射峰位置;改变周期数,则可以影响透射率。这一研究结果对提高光子晶体滤波器性能具有一定参考价值。     

精确测量单轴晶体折射率的一种特殊方法

本文提出一种测量单轴晶体折射率的特殊方法，测量精度达１０＾－４，尤其适用于非棱镜形式的单轴晶体。     

Measurement of the nonlinear refractive index of longdispersion-shifted fibers by self-phase modulation at 1.55 μm

We measure a value of N₂=2.45×10^-16 cm ²/W (±5%) by self-phase modulation (SPM) in two 20 km dispersion-shifted fibers for random polarization at 1.55 μm. There is still some dispersive broadening and we find that an accurate determination of N₂ requires fitting the experimental (SPM) spectra with a computer simulation to account for the variation in pulse shape and fiber properties along the length of the fiber. We also show that spectral information provides information about the input pulse properties     

颗粒膜电介质光子晶体低频折射率问题分析

应用颗粒膜电介质晶体在低频极限下的准静态折射率和静态折射率的关系,分析和计算了光子晶体低频折射率,结果表明：由于低频电磁波诱导的涡流（或极化电流）,使非磁性光子晶体显现反磁性共振,这个共振依赖于周期性颗粒的半径和趋肤深度之间的关系。即,如果趋肤深度远远小于周期性颗粒的半径,包含物内部电磁场被屏蔽,使每一种包含物的行为像理想反磁性体。对于平行颗粒膜平面的（H偏振）电磁波,光子晶体的反磁性磁导率总体上是随填充数的增加而线性的减少;相反的,当趋肤层大于半径,则反磁性体共振可以忽略。周期性颗粒的磁化引起静态和准静态折射率的结论,解释了非对易限制的问题。     

液晶折射率与电压关系的研究

液晶的一个重要特性是：液晶的折射率会随所加于液晶上的电压的变化而变化。本文正是对这一规律进行了研究实验,并得出了实验结果。     

介质折射率对光子晶体量子阱滤波性能的调制

为设计高品质的光学滤波器件,利用传输矩阵法理论,通过数值计算模拟的方法,研究垒、阱层介质折射率对光量子阱滤波带宽的调制机制,结果表明,光量子阱滤波带宽对垒、阱层介质折射率的响应相当灵敏:垒层高折射率介质的折射率越大,光量子阱的滤波带宽越窄;垒、阱层介质的折射率和的比值越大,光量子阱的滤波带宽越窄。光量子阱滤波带宽对介质折射率的响应机制,为提高光子晶体光学滤波器件的品质、性能提供方法依据,同时对光量子阱的理论研究也具有积极的指导意义。     

离子交换单模玻璃平面波导折射率分布的确定

用Ag-Na离子交换技术制备了玻璃平面波导.求解扩散方程得到Ag离子在玻璃内部浓度分布.使用一次多项式模拟的方法求解折射率变化与Ag离子浓度变化之间的关系,从而得到了单模平面波导的折射率分布,并验证其与同等实验条件(离子交换时间除外)的多模波导获得的折射率分布函数基本一致.     

反射z扫描方法测量碲化铋晶体的非线性折射率

为了研究3维拓扑绝缘体碲化铋(Bi2Te3)的非线性光学特性,采用反射z扫描方法,实验测量了800nm飞秒脉冲激光的非线性折射系数。通过理论计算与实验数据拟合获得碲化铋晶体的非线性折射率达到10-14 m2/W数量级,为石英的105倍;随着入射功率的增大,其非线性折射率逐渐减小,在峰值光强达到85GW/cm2后趋于常数不变。结果表明,碲化铋是一种高非线性光学材料,有望应用于全光信号处理、光开关等方面。     

Theoretical investigation of photonic crystal waveguide splitters incorporating ultralow refractive index metallic nanowires

The present letter theoretically investigates the optical properties, and provides design guidelines for optimum performance of a photonic crystal (PC) waveguide splitter composed of ultralow refractive index metamaterials, by utilizing a rigorous analytical modeling based on the scattering matrix technique. We believe that this type of nanocomposite metallic PC waveguide can bring additional degrees of design flexibility to ultradense optical integration, because of its compact size and relatively low-loss propagation characteristics, mainly for power-splitting applications in the visible frequency spectrum.     

Reflection z-scan for measuring the nonlinear refractive index of porous silicon

An experimental investigation on the nonlinear refractive index of nanoporous silicon at wavelengths of 532 nm and 1064 nm is reported by the reflection z-scan(RZ-scan) method with picosecond pulses.The porous silicon(PS) does not need to be peeled from silicon substrate.The method uses a p-polarized beam with oblique incidence.The modification of the reflected beam intensity gives the information of the surface nonlinear refractive index.The index of porous silicon at 1064 nm is at the same order of magnit...     

Analysis of mode locking and ultrashort laser pulses with a nonlinear refractive index

A new method for locking the longitudinal modes of a laser resonator and generating ultrashort pulses of light is described. The cavity modes are coupled together when a medium with a refractive index nonlinearity is placed in the cavity. A theoretical study is presented which analyzes the mode structure of a laser resonator containing a cell filled with an anisotropic molecular liquid. It is found that under certain conditions the energy exchange between the modes gives rise to a mode-locked spectrum and to the attendant generation of ultrashort pulses of light (sim 10^{-11}second for a ruby laser, 10^-12second for a Nd³⁺: glass laser).     

含负折射率介质光子晶体的斜角禁带

研究了由正负折射率介质交替排列构成的光子晶体的传输特性,负折射率材料(NIM)是有损耗的Drude色散媒质。研究发现,这类光子晶体具有零折射率带和传统的Bragg带,此外在NIM的折射率接近于零的频域还出现了一个新型的禁带——斜角带。该斜角带的位置与晶格参数无关,其带宽较小;在电磁波垂直入射时禁带消失,但随着入射角的增大禁带逐渐展宽,且TM模的带宽大于TE模。     

折射率正弦离散变化声子晶体中电磁波的偏振特性

利用特征矩阵法,计算了折射率按正弦规律离散变化的一维声子晶体中TE波和TM波的反射率随入射角变化的规律,得出: TE波和TM波的主禁带有相同的偏振特征,主禁带的入射角范围都较小,在0～0.11rad范围内.主禁带的品质随折射率峰值和周期数的增加而变好.反射波中不会出现"广义布儒斯特角"现象.     

Ti：Mg：LiNbO_3晶体的折射率温度系数表示式

基于在５３９．７５ｎｍ，６３２．８ｎｍ，１０７９．５ｎｍ，１３４１．４ｎｍ波长上和２８８Ｋ，３３８Ｋ，３８３Ｋ，４２３Ｋ温度条件下，对掺５ｍｏｌ％ＭｇＯ和０．２ｍｏｌ％Ｔｉ的ＬｉＮｂＯ＿３晶体的主折射率的精密测量￣［１］，根据对ＬｉＮｂＯ＿３晶体适用的修正的Ｓｅｌｌｍｅｉｅｒ’ｓ方程，以解出参数Ｃ＿ｉ表达式的方法，求出上述温度时Ｓｅｌｌ－ｍｅｉｅｒ’ｓ方程的参数Ａ＿ｉ，Ｂ＿ｉ，Ｃ＿ｉ，Ｄ＿ｉ，以最小二乘法精确地拟合上述参数对温度Ｔ的线性关系，进而推导出这种晶体的折射率温度系数的表示式。利用此表示式可以计算波长在５３９．７５ｎｍ～１３４１．４ｎｍ区间附近，温度在２８８Ｋ～４２３Ｋ范围左右Ｔｉ：Ｍｇ　：ＬｉＮｂＯ＿３晶体的折射率温度系数。为检验该折射率温度系数表示式的实用性，利用此表示式计算１０７９．５ｎｍ为基波的该晶体的二倍频非临界相位匹配温度，与实验值之差在１Ｋ以内，从而证明这个折射率温度系数表示式对于采用Ｔｉ：Ｍｇ：ＬｉＮｂ＿Ｏ，晶体设计非线性光学器件是适用的。     

折射率可调的二维光子晶体设计与特性

光子晶体在传感、滤波和光子晶体激光器等方面具有很重要的应用价值。设计了一种基于改变缺陷介质折射率的可调谐二维正方晶格和三角晶格光子晶体激光器微腔,在平面光子晶体薄板中引入点缺陷磷酸氧钛钾(KTP),在KTP两端施加交流电场控制KTP晶体折射率变化。实验中随着KTP晶体折射率逐渐增大,正方晶格光子晶体禁带数量减少,归一化频率减小,禁带宽度基本不变;而三角晶格光子晶体禁带逐渐变窄,且向低频方向移动。最后,用平面波展开法分析了晶体的能带结构,得到理论上的描述,验证了实验结果。