Far-infrared guided wave optics experiments with anisotropic crystal quartz waveguides

The TE and TM modes of anisotropic dielectric waveguides of crystal quartz have been studied in the far infrared using an optically pumped waveguide laser with a hybrid output mirror. Using Si and Ge prism couplers, excitation efficiencies of 56 percent of the theoretically calculated values were obtained for the TE0mode. The measured propagation constants were found to agree closely with theory when the perturbation of the guided modes by the prism couplers was included. The attenuation constant for the TE0mode atlambda_{0} = 496.1mum was found to be as low asalpha_{TE_{0}} = 0.05cm^-1. A metal grating coupler for backward-wave coupling through a prism shaped TPX plastic substrate was also used to couple 89 percent of the guided energy in the TE0mode out of the waveguide in the reverse direction.     

High resolution spatial interferometry of guided optical waves

The spatial variation of the phase difference Φ(z) between collinear guided waves is measured interferometrically by scanning a localised perturbation along the guide. Milliradian phase resolution is achieved by the use of a quadrature signal. The method is demonstrated with TE⇔TM coupling in Ti:LiNbO₃. It yields the absolute value and the uniformity of the birefringence Δβ(z)=dΦ/dz     

Propagation and optical interaction of guided acoustic waves intwo-mode optical fibers

Acoustic modes propagating in cylindrical solid rods are considered. A review of the properties of several mode groups is given, and computed results are shown for a wide range of material properties. The lower mode of each group is relevant for an all-fiber-optic frequency shifter recently demonstrated. For these modes, dispersion relations, mode patterns, power relations, and acoustooptic coupling strength are calculated. Some experimental results are compared with the calculations, and alterations to improve the frequency shifter are proposed     

光导波的声光布喇格偏转

光导波声光Bragg偏转器有可能应用于宽带射频信息的处理。本文介绍光导波声光Bragg偏转器的设计、制作与实验结果。 1.光波导结构与耦合 光波导基片为y切LiNbO_3,晶轴的x、y和z方向分别约为40毫米、2毫米和10毫米。GOW沿x轴传播,SAW沿z轴传播。基片表面经严格光学抛光。用电子束热蒸发在其表面沉积一层约300(?)厚的Ti膜,经1000℃氧气氛下扩散而成渐变折射率光波导。用一锗酸铋棱镜把He-Ne激光器的6328(?)光耦合到波导中,可分别激励TE模和TM模的各个模式,再用同样的棱镜将制导光束耦合出来。TK_o模穿透深度约为3微米,波导损耗约为2分贝/厘米。     

Acousto-optic diffraction by an acoustic surface wave in an ion-exchanged waveguide

We have investigated acousto-optic diffraction by an acoustic surface wave generated by a ZnO-thin-film transducer in an ion-exchanged waveguide. A diffraction efficiency of 70% was obtained with 2 W of electric power.     

Acousto-optic measurements of effective refractive indices of guided modes in planar waveguides

New simple acousto-optic (AO) methods of determination of guided-mode propagation constants in planar waveguides are considered. Some promising advantages are shown of the AO methods in the cases of anisotropic waveguides. Experimental verifications of YX-LiNbO3 Ti-diffused single-mode waveguides have been obtained.     

基于光子晶体平板传导共振模的低功率光开关

利用严格耦合波算法计算了二维光子晶体平板结构随角度变化透过谱和波长变化透过谱,研究了透过谱上传导共振峰与二维光子晶体平板能带结构的关系。利用共振传导模的低透过和高Q值的特点,设计了基于磷化铟材料的工作在1550nm波长附近的角度分辨和波长分辨的光子晶体光开关。理论模拟结果表明,该结构透过谱上传导共振峰品质因子可达105,非线性折射率变化为10-4即可实现开关对比度接近100%。当信号光或泵浦光分别与光子晶体平板传导共振模耦合时,由于共振耦合使得泵浦光场增强,需要泵浦能量仅为184fJ,为目前所知能量最低的光开关。     

Spectroscopic studies of optical materials in the far infrared: The case of crystal quartz

Spectroscopic studies using far infrared reflectivity and transmissivity measurements between 10 and 600 cm^?1, were performed on plane parallel quartz crystal plates, in the temperature range 10–300 K. The temperature dependence of the optical mode parameters is reporeted for both polarizations parallel and perpendicular to the c-axis. The extraordinary optical constants of quartz are determined at 10 and 300 K, from the A₂ transmissivity channeled spectrum, between 10 and 300 cm^?1.     

高振动石英晶体振荡器

新的设备特性使苛刻应用中的频率控制更稳固 我们通常认为在电子系统中,石英晶体振荡器是最易碎的元件之一.     

Dispersive Rayleigh waves on quartz

The dispersive properties of Rayleigh waves propagating in the xdirection of ycut quartz have been measured with thin films of gold, copper and silver deposited on the free surface. It is found that the attenuation of the surface waves increases sharply with increasing thickness of the metallic films.     

Anomalous nonlinearity in quartz crystal filters

A survey of the third order intermodulation performance of individual crystal units from commercial 10.7 MHz filters is presented. The intermodulation distortion is found to vary significantly with drive levels in the range 0 dBm to ?60 dBm.     

Nonlinear guided waves in multilayer systems

A nonlinear matrix formalism that allows the calculation of the optical field within a nonlinear multilayer system is presented. Taking advantage of this technique, the field profiles are calculated and the dispersion relation of nonlinear guided waves in such configurations is derived. The numerical results reveal that several field profiles occur, each attached to a certain unit cell of the multilayer system. The various field profiles apply to the corresponding branches of rich structured nonlinear dispersion curves. A comparison of the results of those yielded by an effective medium model is carried out. Appreciable differences are found and are discussed in detail     

Attenuation of dispersive Rayleigh waves on quartz

The attenuation properties of Rayleigh waves propagating in the x direction of y cut quartz have been measured with various metal films in the 30?157 MHz frequency range. The strong increase in the attenuation with film thickness is explained in terms of mechanical coupling and energy losses in the amorphous-metal films.     

Polymer-coated quartz crystal resonators for multi-informationsensing

A study of polyphosphazene-coated QCRs gas sensors using both mass and electrical loadings has been performed. In addition to the device series resonance frequency, the parallel resonant frequency was measured in an attempt to characterise the changes in the dielectric properties of the coating during the detection process. The result is a sensor with an additional parameter to improve selectivity     

激光衍射法测量表面波的衰减系数与频率的关系

对于频率为几百赫兹的液体表面波,实验上观察到稳定、清晰、反衬度非常高的衍射图样.理论上得到了衍射条纹间距、表面波波矢量与衰减系数之间的解析关系,并建立了表面波衰减特性的检测方法和实验装置.观察到表面波的衰减效应及衰减系数的色散效应,结果表明衰减系数随频率几乎成线性关系,与理论值吻合.     

TM-polarized nonlinear guided waves in multilayer systems

The ability of various multilayer systems to support TM-polarized nonlinear guided waves is studied. A flexible numerical technique which includes the proper consideration of the nonlinear crossing conditions is used to calculate the field profiles and derive the dispersion relations. The fundamentals of the model are described, and the algorithm is applied to several nonlinear film configurations. For the sake of comparison with the finite-element method, a single linear film, embedded between two nonlinear materials, is treated. A three-film unit cell, consisting of a high-index linear film, sandwiched between two low-index nonlinear, ones is considered. This is the elementary unit cell of a composite geometry, a ten-unit-cell superlattice, which is then studied. It is found that unlike TE-polarized nonlinear guided waves in multilayer systems, the TM waves reveal a distinct power maximum. The inclusion of saturation effects in the analysis is straightforward     

抗高过载石英晶体元件的研制

使用一种简单实用的设计方法,采用特殊的结构设计,研制出的石英晶体元件具有抗高过载的能力.这种产品可制作的频率范围是3～60MHz,具有抗冲击力在1000～20000g,结合试验验证,这种石英晶体元件在经受高冲击后,仍然能够稳定的工作,所以充分证明了石英晶体元件通过采用这种特殊的结构,完全可以达到具有抗高过载（冲击力在1000～20000g）的能力.解决的关键问题是石英晶体元件晶片的设计、结构的设计及加工过程中应注意的问题.     

Analysis of guided waves in inhomogeneous bianisotropic cylindricalwaveguides

Electromagnetic fields in structures composed of inhomogeneous cylindrical layers are analyzed using a propagator matrix approach. The presented formulation is capable of analyzing fully bianisotropic media, where the involved propagator matrix for bianisotropic media is derived in cylindrical coordinates. The applicability of the method is demonstrated by calculating the dispersion characteristics of surface waves as well as fundamental and higher order modes on cylindrical microstrip lines on top of an inhomogeneous bianisotropic substrate