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1.
双锥光纤滤波器的研制 总被引:4,自引:1,他引:3
实验研究了熔锥条件对双锥光纤滤波器的影响。提出一个高斯模型,预测锥的几何形状。获得了窄带带通双锥光纤滤波器以及带阻中心波长分别为135nm和1559nm的带阻双锥光纤滤波器。 相似文献
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实验发现在保持入射到晶体表面的泵浦光斑尺寸不变的条件下,随泵浦光的入射位置和入射角不同,自泵浦相位共轭形成机制在FWM-TIR、FWM-SPB和FWM-TIR与FWM-SPB之间转变. 相似文献
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为了消除群速失配对参量放大的不利影响,描述了利用脉冲波面倾斜与非共线相位匹配相结 合,完全补偿飞秒光参量放大(OPA)中三波群速失配的新方法.计算了在BBOⅠ类、Ⅱ类相 位匹配条件下, 三波实现群速匹配时,相位匹配角、脉冲波面倾斜角以及非共线角随信号 光波长的变化.并分析了三波群速匹配对空间走离长度、参量增益和参量带宽的影响.结果表 明,在BBOⅠ类、Ⅱ类相位匹配条件下,利用该方法均能实现飞秒OPA连续调谐时三波的群速 匹配,从而大大增加了三波的有效互作用长度,为能够获得高增益,窄脉宽的参量光脉冲提 供了理论依据和指导.
关键词:
群速匹配
脉冲波面倾斜
非共线相位匹配
飞秒光参量放大 相似文献
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Yoshihisa Takayama Atsushi Okamoto Kunihiro Sato Kazuhumi Kumagai Yugo Aizawa 《Optical Review》1998,5(1):49-53
We consider the optimum incident angles of cross polarized four-wave mixing with a photorefractive crystal. First, the phase matching angles are obtained for two operation modes: one in which the writing beams are ordinary rays and the reading beam is an extraordinary ray, we call this Mode 1. The other in which the writing beams are extraordinary rays and the reading beam is an ordinary ray, Mode 2. Next, practicable ranges of the incident angles are calculated considering of the total internal reflection of the phase conjugate beam in cases where the two writing beams illuminate the same surface of the BaTiO3 crystal and where they illuminate the neighboring right-angled surfaces, respectively. Then, the coupling coefficient is determined as a function of the incident angle, and the optimum incident angles for effective beam interaction in Mode 1 and Mode 2 are estimated. 相似文献
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Lateral displacements of well-focused beams reflected from absorbing media are demonstrated in this paper. The incident beam is modeled as a tapered wave with a Gaussian spectrum. The field solutions are obtained on both sides of the interface by solving analytically from Maxwell's equations and by matching the boundary conditions at the interface. Numerical simulations are presented and the field values as well as the time-averaged power densities are computed. The influences of the polarization, the angle of incidence and the beam width on the displacement are discussed. The origin of the displacement lies in the absorption of the media, for which there is a phase shift between the incident and reflected waves. Because of this phase shift, the center of the reflected beam does not coincide with that of the incident one, similar to the Goos-Hänchen shift. 相似文献
7.
Optical properties of polarization-dependent geometric phase elements with partially polarized light
Yuri Gorodetski 《Optics Communications》2006,266(2):365-375
The behavior of geometric phase elements illuminated with partially polarized monochromatic beams is investigated both theoretically and experimentally. The element discussed in this paper is composed of wave plates with π-retardation and a space-variant orientation angle. We found that a beam emerging from such an element comprises two polarization orders; right-and left-handed circularly polarized states with conjugate geometric phase modification. This phase equals twice the orientation angle of the space-variant wave plate comprising the element. Apart from the two polarization orders, the emerging beam coherence polarization matrix includes a “vectorial interference matrix” which contains information concerning the correlation between the two orthogonal, circularly polarized portions of the incident beam. In this paper we measure this correlation by a simple interference experiment. In addition, we found that the equivalent mutual intensity of the emerging beam is modulated according to the geometric phase induced by the element. Other interesting phenomena concerning propagation will be discussed theoretically and demonstrated experimentally. The experiment made use of a spherical geometric phase element that was realized by use of a space-variant subwavelength grating illuminated with CO2 laser radiation of 10.6 μm wavelength. 相似文献
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Axisymmetric Bessel-modulated Gaussian beam with quadratic radial dependence (QBG beam) has attracted much attention recently. In this paper, the focal shift of the cylindrical vector QBG beam with radial variance phase wavefront is investigated theoretically by vector diffraction theory. Results show that focus shifts considerably by changing the phase parameter C that indicates the radial phase variance speed. Under condition of small beam parameter μ of cylindrical vector QBG beam, there is one focal peak that shifts far away from optical aperture on increasing C. When μ increases, there may occur two focal peaks that also shift remarkably on increasing C. And it was found that the dependence of focal shift distance on increasing phase parameter is linear. Phase parameter adjusts the focal shift distance, while, polarization angle does not affect focal shift obviously. 相似文献
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实验发现当光入射到晶体表面的泵浦光斑尺寸较小时,无论入射角和入射位置怎样,擦除光对相位共轭反射率没有影响,同时从上表面可观察到全内反射的光回路,所以SPPC的形成机理为FWM-TIR;当入射到晶体表面的泵浦光斑尺寸较大时,在一定的入射角和入射位置,擦除光的作用使相位共轭反射率很快减小,表明这时的SPPC的形成机理为FWM-SPB. 相似文献
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Both supercontinuum conical emission (SCCE) and blue-green conical emission (CE) by means of second harmonic generation (SHG) were observed alternately in a β-barium borate (BBO) crystal induced by femtosecond laser pulses with vertical polarization state. Three theoretical models were analyzed to interpret the angular beam of SCCE. The experimental conical angles with different wavelengths in BBO crystal and BK-7 glass can be explained well by nonlinear X-wave model and Cerenkov type phase matching model other than four-wave mixing (FWM) model. 相似文献
11.
利用分步快速傅里叶变换和四阶龙格-库塔法,对具有一定温升分布的倍频晶体的二次谐波转换过程进行了研究。综合考虑了谐波转换过程中的离散、衍射、二阶、三阶非线性等效应,着重讨论了倍频晶体吸收光能后,晶体内温升分布对晶体内o光和e光的折射率分布的影响,定量分析了温度分布引起的相位失配量、输出光场分布、二次谐波转换效率随倍频晶体温度分布变化的规律。结果表明:在高功率倍频系统中,倍频晶体温升分布引起基频光、倍频光的相位失配,相位失配导致输出光场光强分布的变化以及谐波转换效率的降低。 相似文献
12.
Atsushi Okamoto Hisashi Matsuoka Motoki Saito Yoshihisa Takayama Mototsugu Takamura 《Optical Review》1999,6(3):189-195
We propose a new optical network device photorefractive connection module (PRCM) which operates as optical switch, amplifier and signal distributor controlled by parallel optical signals. Simple optical control bus systems can be realized by cascade connection of PRCMs. PRCM branches off a desired channel from the spatial multiplexed optical bus line by appropriate setting of the control beam pattern. PRCM uses cross polarized four wave mixing (CPFWM) with extraordinary polarized writing beams and an ordinary polarized reading beam to achieve a high connection gain to the next PRCM stage. We analyze the phase matching angle of CPFWM in which the optical paths of two pump beams are slightly different. The phase conjugate reflectivity indicating a branching ratio of optical signal is derived and calculated in consideration of the phase mismatching Δk. The optimum pump ratio and the grating vector orientation for the largest phase conjugate reflectivity and signal amplification factor are discussed for optical design of PRCM. Since the measured signal beam power after passing through the BaTiO3 crystal is three or four times higher than its incident power, PRCM has a sufficient connection gain for optical bus and interconnection systems. 相似文献
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给出高斯入射束反射时角位移直接计算式,适用于任意入射角和反射介质有吸收的情况。计算式在布儒斯特角上不存在发散困难,对于P偏振和S偏振均适用,只要令g1=n1,g2=0计算所得即为S偏振的角位移。 相似文献
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In this paper, the internal field distribution of higher order MDRs of water droplets is calculated and the result shows that the higher order MDRs should dominate the nonlinear couple process. Furthermore, the phase matching required for four-wave mixing (FWM) process in the droplet is interpreted as the concept of angular momentum conservation. The slight mismatch in angular momentum leads to significant improvement of phase matching than that in optical cell. 相似文献
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一种基于相位测量的角漂移自适应结构表面等离子体共振气体折射率测量系统 总被引:1,自引:0,他引:1
提出了一种可抑制角漂移的表面等离子体传感器结构,并结合相位测量设计了相应的气体折射率测量系统。分析表明激光入射角、金膜厚度以及反射光p、s分量的相位差与气体折射率之间的固有非线性是影响相位响应度与折射率测量精度的主要因素。计算表明所提出的自适应结构将角漂移引起的误差降低了一个数量级并很大程度提高了测量灵敏度。同时分析设计了金膜厚度参数,并评估了反射光p、s分量的相位差与气体折射率之间固有非线性带来的误差。应用于空气折射率的测量比对实验显示其测量精度达到了10-6量级。 相似文献
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利用衍射积分公式数值模拟了不同阶次的空间变化偏振矢量贝塞尔高斯(BG)光束经过强聚焦系统后在焦点附近的强度分布。数值结果显示空间变化偏振矢量BG光束聚焦后在光束传播轴负方向存在焦斑移位现象,其焦斑移位的大小与光束的模阶次、光束宽度、波长以及局部偏振状态密切相关。矢量光束偏振态的变化依靠液晶相位延迟器(LCVR)的相位延迟角度来控制,由于LCVR的相位延迟角度可以在0~π之间连续变化,从而改变光束的局部偏振状态,间接实现了对矢量光束焦斑移位大小的实时控制,在光学微操纵领域具有潜在的应用价值。 相似文献
19.
Phase dispersion of Raman and Rayleigh-enhanced four-wave mixings in femtosecond polarization beats 下载免费PDF全文
Based on color-locking noisy field correlation in three Markovian
stochastic models, phase dispersions of the Raman- and
Rayleigh-enhanced four-wave mixing (FWM) have been investigated. The
phase dispersions are modified by both linewidth and time delay for
negative time delay, but only by linewidth for positive time delay.
Moreover, the results under narrowband condition are close to the
nonmodified nonlinear dispersion and absorption of the material.
Homodyne and heterodyne detections of the Raman, the Rayleigh and
the mixing femtosecond difference-frequency polarization beats have
also been investigated, separately. 相似文献
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突破传统涡旋光场束缚,发展短波极紫外涡旋光场是实现阿秒脉冲偏振控制的有效途径.本研究利用自制的平场光栅光谱仪和超快时间保持的单色仪,以800 nm,35 fs高斯或具有偏振奇点的涡旋光脉冲驱动诱导氩原子产生高次谐波,分别获得相应的高次谐波光谱以及谐波谱单阶光源的分布.实验结果表明,基于高次谐波产生实现近红外波段的涡旋光束特性转移到极紫外波段,优化后的极紫外涡旋可以实现每秒108光子数输出.同时发现极紫外波段的涡旋场和高斯场高次谐波产生具有相似相位匹配机制.基于高次谐波产生的极紫外波段的偏振涡旋光为探究和操控原子分子量子态的含时演化动力学以及形成阿秒矢量光束提供了重要的方法和技术手段. 相似文献