Long-range surface plasmon polariton waveguides embedded in fluorinated polymer

Low-attenuation waveguides based on the propagation of long-range surface plasmon polaritons (LRSPPs) along thin Au stripes embedded in low absorption perfluorocyclobutane (PFCB) polymer are presented. A new low in propagation loss of <2.0 dB/cm was achieved for a 4 microm wide waveguide by optimizing the cladding material and fabrication process. The coupling efficiency between the LRSPP waveguide and the optical fiber is studied theoretically and experimentally for different widths of Au stripes and various cladding thicknesses. Lower coupling loss is found when the cladding thickness is close to the mode diameter of the butt-coupled fiber. Based on the 2D distribution of SPP modes calculated by a finite-difference mode solver, a symmetric structure of multilayer claddings with different refractive indices is proposed to optimize device insertion loss.     

Low loss, low refractive index fluorinated self-crosslinking polymer waveguides for optical applications

Synthesis and optical applications of low loss methacrylate-based fluorinated polymers are described. The synthesis of well defined self-crosslinking fluorinated polymers has been carried out in order to tune refractive index in the range of 1.390 < n < 1.450. After thermal crosslinking, one single lithographic step followed by reactive ion etching is necessary to monomode optical waveguide fabrication on silicon substrates. Optical losses lower than 1 dB/cm at 1300 nm and 2 dB/cm at 1550 nm were measured for highly confined modes. Efficient chip coupling to lensed optical fibers was obtained. Using waveguides with an effective index close to that of bulk silica, a significant coupling interaction between the guided modes and the whispering gallery modes of a silica microsphere was evidenced thus opening the way for new device applications.     

Ultimate performance limitations of high-power ferrite circulators and phase shifters

The power-handling capability of circulators and phase shifters in rectangular waveguide is analyzed. It is shown that an appropriate measure of the suitability of microwave ferrites for high-power applications is given by the "high-power figure of merit"F_{hp}* = 4piMgamma^{2}h_{crit}/omega^{2}mu'. Here γ is the gyromagnetic ratio, hcritthe critical RF field, ω the (angular) frequency,mu"the imaginary part of the diagonal component of the permeability tensor. In applications to nonlatching devices,Mis the saturation magnetization; in applications to latching devices it is the remanent magnetization. The figures of merit of various rare-earth substituted garnets are reported. The figures of merit obtained to date are approximately 2. Theoretical analysis indicates that significantly larger figures of merit can be Obtained only at the cost of reducing the saturation magnetization. It is concluded that for circulators using theH-plane configuration and having an insertion loss of 0.5 dB the maximum attainable peak power level is of the order of 50 MW. For latching twin slab phase shifters (E-plane configuration) having an insertion loss of 1 dB the maximum attainable peak power level is estimated to be 80 kW.     

Application of discrete variable SHF phase shifters in modulation-type amplitude-phase meters

Translated from Izmeritel'naya Tekhnika, No. 9, pp. 37–39, September, 1988.     

Digital phase shifters in frequency converters of precision time and reference frequency systems

Translated from Izmeritel'naya Tekhnika, No. 5, pp. 32–34, May, 1990.     

Experimental studies of electro-optic polymer modulators and waveguides

The results of an experimental study of electro-optic modulators and waveguides based on polymeric materials are presented. Included are the design, fabrication, and testing of integrated Mach-Zehnder modulators, which are based on polymer films that contain a novel, nonlinear electro-optic chromophore. Studies also show the efficacy of photolithography or photobleaching by the use of this chromophore to form passive, branching waveguides, which are operated at the 1300-nm wavelength.     

Digital phase shifters in automatic frequency control systems of quantum frequency standards

Methods are discussed for improving the metrological characteristics of quantum frequency standards and, in particular, their accuracy. The application of digital phase shifters in frequency conversion circuits is considered. It is shown that improvement of the reference signal spectrum of the AFC system makes it possible to increase the frequency standard accuracy by one to two orders of magnitude without affecting the output signal stability.Translated from Izmeritel'naya Tekhnika, No. 12, pp. 26–29, December, 1995.     

Domain-controlled polymer alloy composed of segmented polyurethane and phospholipid polymer for biomedical applications

Segmented polyurethane(SPU)s are block polymers which have a good elastic property and thermoplasticity. However, the biocompatibility of SPU is not sufficient, and a living organism rejects the SPU as a foreign material. Thus, some modification is needed to provide excellent biocompatibility and retain the good physical characteristics of the SPUs. In this study, we blended the 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer with SPU to prepare an SPU/MPC polymer alloy. We investigated the effects of the molecular weight (M_w) of the MPC polymer on the microdomain structure and mechanical property of the polymer alloy. When the MPC polymer with a higher M_w was blended with SPU, the polymer alloy underwent a reduction in mechanical strength. On the other hand, even when the lower M_w of the MPC polymer was blended with SPU, differential scanning calorimetric analysis revealed that the MPC polymer chains did not disrupt the crystallinity of the hard segments of SPU and the polymer alloy could maintain its physical properties the same as that of the original SPU. We investigated the adsorption of immunoglobulin (IgG) on the surface of the polymer alloy for evaluation of its fundamental biocompatibility. The SPU/MPC polymer alloy lowered the amount of adsorbed IgG compared to that on SPU. This means that the blending of the MPC polymer significantly improved the biocompatibility of the SPU. We succeeded in preparing an SPU/MPC polymer alloy that possesses both the good mechanical property of SPU and the improved biocompatibility using MPC polymers.     

Domain-controlled polymer alloy composed of segmented polyurethane and phospholipid polymer for biomedical applications

Segmented polyurethane(SPU)s are block polymers which have a good elastic property and thermoplasticity. However, the biocompatibility of SPU is not sufficient, and a living organism rejects the SPU as a foreign material. Thus, some modification is needed to provide excellent biocompatibility and retain the good physical characteristics of the SPUs. In this study, we blended the 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer with SPU to prepare an SPU/MPC polymer alloy. We investigated the effects of the molecular weight (M_w) of the MPC polymer on the microdomain structure and mechanical property of the polymer alloy. When the MPC polymer with a higher M_w was blended with SPU, the polymer alloy underwent a reduction in mechanical strength. On the other hand, even when the lower M_w of the MPC polymer was blended with SPU, differential scanning calorimetric analysis revealed that the MPC polymer chains did not disrupt the crystallinity of the hard segments of SPU and the polymer alloy could maintain its physical properties the same as that of the original SPU. We investigated the adsorption of immunoglobulin (IgG) on the surface of the polymer alloy for evaluation of its fundamental biocompatibility. The SPU/MPC polymer alloy lowered the amount of adsorbed IgG compared to that on SPU. This means that the blending of the MPC polymer significantly improved the biocompatibility of the SPU. We succeeded in preparing an SPU/MPC polymer alloy that possesses both the good mechanical property of SPU and the improved biocompatibility using MPC polymers.     

Light transport in quasi-one-dimensional disordered waveguides composed of locally two-dimensional random square lattices

We present numerical studies on the light transport properties which are tuned by the disorder strength in quasi-one-dimensional disordered waveguides consisting of periodically arranged scatterers with random dielectric constant. The transport mean free path is found to be inversely proportional to the square of the relative fluctuation of the dielectric constant as in the 1D and 2D cases but the proportionality coefficient is between those of 1D and 2D. The transport properties of light through a sample with a fixed size can be tuned from ballistic to localized regime as well, and a generalized scaling function is introduced to determine the light transport status in such a sample. The calculation of the energy density profile of the most transmitted eigenchannel clearly exhibits the transition of transport behaviour from diffusion to localization.     

Thermal conductivity of some deuterated compounds in the gaseous phase

The results of measurements of the thermal conductivity of CD₄, CH₄, C₂D₄, and C₂H₄ in the temperature range of 300–650°K are presented. The question of the influence of the isotopic effect on the transfer coefficients in gases is discussed.     

Grating-enhanced second-harmonic generation in polymer waveguides: role of losses

A numerical study of second-harmonic (SH) generation in a corrugated polymer waveguide is performed with a rigorous electromagnetic theory. Comparison with experiment reveals the role of losses inside the waveguide-small losses do not significantly affect the nonresonant response and reduce the resonant enhancement of SH generation. High losses can lead to the opposite effect-instead of enhancement, dips in the SH efficiency are observed in the vicinity of guided-wave excitation. The peculiarities of the angular dependencies of SH generation are explained from the phenomenological point of view, and the role of phase matching is discussed.     

Preparation of rib channel waveguides on polymer in electric field

Micro-sized patterns were created on oligomer (Su-8) films by the effect of external electric field, perpendicular to the film surface. Structures with varying parameters were prepared and the growth of continuous or dot-like structures was observed. The mechanism dominating the structure growth was examined and found to be a function of experimental conditions. The dependence of the form and the size of the created patterns on the intensity of the electric field, exposure time and initial distance between mask and polymer surface was investigated. Waveguiding properties of the linear pattern, produced by the above technique, were examined and the following parameters were obtained: propagation loss — 2-3 dB/cm, effective refractive index — 1.6276, number of supported modes — 30).     

Analysis of hybrid beams composed of GFRP profiles and polymer concrete

In this paper, a numerical approach for the analysis of a new type of hybrid composite beams is presented. Such beams are composed of composite materials that resist shear and tensile stresses, and polymer concrete acommodating compression stresses.The beams offer an optimized configuration in terms of stiffness and strength, with much potential for mechanical and civil engineering structures.The current numerical model is based on a finite element formulation for layered shell-like structures. The model accounts for a polymer concrete material model, orthotropic material model, and considers the analysis of geometric and material nonlinearities. The first-order shear deformation theory is used in order to describe the shell deformation under a total Lagrangian formulation. The model is validated experimentally and a close agreement with experimental results makes this model an attractive solution method for this type of composite hybrid beams.     

Device for measuring the parameters of controlled discrete phase shifters of antenna systems

Translated from Izmeritel'naya Tekhnika, No. 12, pp. 36–38, December, 1988.     

The elastic behaviour under hydrostatic pressure of poly(methyl methacrylate) and its fully deuterated form

Measurements have been made of the effects of hydrostatic pressure on the velocities of longitudinal and shear ultrasonic waves propagated in a commercial poly(methyl methacrylate) (PMMA) and a fully deuterated PMMA. The experimental results provide a comparison of the bulk and shear moduli and their hydrostatic pressure derivatives for the two polymers. The vibrational anharmonicity of the long wavelength acoustic modes is more pronounced in the deuterated than in the commercial PMMA. B/P is 32% larger in the deuterated form than in the undeuterated polymer, a finding which may be understood by including the isotopic mass difference in a simple vibrational model.     

甲基丙烯酸缩水甘油酯改善木塑复合材料性能

选用甲基丙烯酸缩水甘油酯(GMA)作为偶联剂,探索了对杨木/塑料复合材料的力学性能和耐久性的改善;并利用SEM和FTIR分析了GMA加入苯乙烯单体(St)前后,高聚物与木材的界面复合效果与反应机制。SEM和FTIR的分析结果表明：GMA借助其自身的环氧基团,实现了与木材细胞壁上羟基的化学键合,且通过自身的双键实现了与单体St的共聚合,最终使高聚物与木材细胞壁较充分地实现了化学键联;高聚物以立体交联的形式填充于细胞腔中,与细胞壁紧密接触,无明显缝隙,复合效果良好。综合性能测试结果表明：GMA的加入,使改性木塑复合材料的静曲强度(MOR)、弹性模量(MOE)、顺纹抗压强度和硬度较未改性前分别提高45%、52%、71%和141%;尺寸稳定性较未改性前提高3倍;耐腐性较未改性前提高8.56倍。     

Integration of polymer waveguides for optical detection in microfabricated chemical analysis systems

Multimode polymer waveguides and fiber-to-waveguide couplers have been integrated with microfluidic channels by use of a single-mask-step procedure, which ensured self-alignment between the optics and the fluidics and allowed a fabrication and packaging time of only one day. Three fabrication procedures for obtaining hermetically sealed channels were investigated, and the spectrally resolved propagation loss (400-900 nm) of the integrated waveguides was determined for all three procedures. Two chemical absorbance cells with optical path lengths of 100 and 1000 microm were furthermore fabricated and characterized in terms of coupling loss, sensitivity, and limit of detection for measurements of the dye bromothymol blue.     

Synthesis and characterization of polyurethane/polybutyl methacrylate interpenetrating polymer networks

A series of castor oil based polyurethane (PU) and poly (butyl methacrylate) (PBMA) interpenetrating polymer networks (IPNs) (PU/PBMA; 80/20, 60/40, 50/50, 40/60 and 20/80) were prepared by sequential polymerization method using toluene diisocyanate (TDI), dibutyl tin dilaurate (DBTL) as catalyst and ethylene glycol dimethacrylate (EGDM) as crosslinker. Tensile strength, percentage elongation at break and surface hardness; FTIR and optical properties of the IPNs are reported. Thermo gravimetric analyzer (TGA) studies of the IPNs are performed in order to establish their thermal stability. TGA thermogram shows that the thermal degradation of IPN was found to proceed in three steps. The microcrystalline parameters such as crystal size (N) and lattice disorder (g in%) of IPNs have been estimated using wide angle X-ray scattering (WAXS) studies. The surface morphology of the IPNs has been studied using scanning electron microscope (SEM).     

Design of a vector-sum integrated microwave photonic phase shifter in silicon-on-insulator waveguides

An orthogonal vector-sum integrated microwave photonic phase shifter (IMWPPS), consisting of mode-order converter multiplexers (MOCMs), a variable optical power splitter (VOPS), an optical switch (OS) and fixed time delay lines (FTDLs), was theoretically demonstrated in a silicon-on-insulator wafer. MOCMs, as a key element of our device, were employed to generate orthogonal vector signals and served as lossless optical combiners. Combining with the thermo-optical VOPS, OS and FTDLs, the microwave phase shift of 0～2π could be achieved by a refractive index variation of 0～15×10(-3) in the millimeter wave band. The corresponding tuning resolution was about 1.64°/°C. This work, for the first time to our knowledge, provides an attractive solution to transferring a vector-sum method based bulk MWPPS into a integrated one, which is very important for large-scale optically controlled phase array antenna.