Microstrip bandpass filters based on zeroth-order resonators with complementary split ring resonators

The zeroth-order resonant (ZOR) properties of the left-handed material (LHM) unit cells composed of complementary split ring resonators and series gaps are analysed. The method to determine the resonant frequency and susceptance slope parameter is proposed. A bandpass filter (BPF) is designed by connecting the ZORs with admittance inverters. Experimental verification is provided and a good agreement has been found between the simulation and measurement. Compared with the bandpass structure fabricated by simply cascading the same amount of LHM unit cells, the proposed BPF has much better selectivity, more symmetrical responses and controllable bandwidth.     

Numerical and experimental studies of split ring resonators loaded on the sidewalls of rectangular waveguides

This work investigates the use of a lattice comprising split ring resonators (SRRs) as a negative permeability medium to achieve backward travelling modes within a rectangular waveguide. The loadings of such SRR-type periodic structures into a waveguide can be tailored such that the backward mode exists in a passband below the ordinary basic modal cutoff frequency, thus affording filtering capabilities and miniaturisation. Theoretical studies by two approaches are performed here, a moment method spectral domain analysis, and a commercial simulation tool. Parametric studies that characterise the effects of various dimensional and electrical properties on the dispersion behaviour of the SRR-loaded waveguide shall also be conducted. The SRR parameters are then optimised using the ant colony optimisation (ACO) algorithm to achieve a low backward passband, for a high degree of miniaturisation and isolation. Experimental results of measurements performed on a manufactured prototype of the optimised SRR-loaded waveguide will also be presented.     

基于分形互补开口环谐振器的复合左右手传输线研究

提出了一种基于Minkowski分形互补开口环谐振器(CSRRs)的电小平衡复合左右手传输线(CRLH TL)(单元尺寸为..074A,).采用理论计算、电磁仿真、等效电路模型计算(电仿真)及有效介质参数提取相结合的方法研究了非平衡CRLH TL传输特性随CSRRs环数、Minkowski环水平迭代因子、垂直迭代因子及...     

Analysis on transmission characteristics of nested ring resonators

The transmission characteristics of the nested ring resonator are analyzed. The intensity transmission of the resonator is obtained. Based on this, the critical coupling and coupled-resonator-induced transparency conditions are derived as length ratio of the U-shaped loop and the inner circle ring is an integer or half-integer. Accurate expressions of these two conditions are provided. Numerical calculation at some specific parameters verifies the conditions and demonstrates their variations vs. parameters of the resonator.     

Influence of the seed layer on structural and electro-acoustic properties of sputter-deposited AlN resonators

The growth of high-quality AlN films has been studied by reactive sputtering onto Mo electrodes with Ni, Ti, and TiW seed layers and subsequent integration into thin film bulk acoustic wave resonators. The crystalline structure and morphology of the Mo and c-axis oriented AlN films were found to vary strongly with seed layer material and thickness. The smoothest Mo electrodes were obtained on thin Ti films. Reactive sputtering of AlN on top of these optimized electrodes resulted in a dense columnar grain structure with a well-aligned (002) crystal orientation and good electro-acoustic properties, including an effective coupling coefficient of 6.89% and quality factor above 1000.     

Polarization beam splitter based on honeycomb-lattice photonic crystal ring resonators

A new polarization beam splitter is proposed based on a photonic crystal ring resonator (PCRR) composed of honeycomb-lattice cylindrical silicon rods in air. By shrinking the width of the bus waveguide and adjusting the radii of two nearest-neighbor center rods of the PCRR, an unpolarized beam can be separated well into TE and TM polarization states, respectively, at the backward and forward output ports. Simulation results obtained by the two-dimensional finite-difference time-domain technique show that the insertion losses are 3.58 dB and 3.08 dB, and the polarization extinction ratios are 21.42 dB and 28.53 dB for TE and TM polarization, respectively, at a 1566.7 nm center wavelength. The excess loss is less than 0.34 dB and its dimensions are roughly 43.2 μm × 27.52 μm. These findings offer potential practical applications in high-density photonic integrated circuits.     

含刚性环结构的紫外光固化低聚物制备及其性能研究进展

含苯环、萘环、蒽环和菲环刚性结构的紫外光固化低聚物由于结构的不同,其制备方法与应用性能具有很大差异.介绍了含刚性环结构的紫外光固化低聚物的制备反应及其应用性能研究进展,重点评述了含苯环结构的环氧丙烯酸酯、聚氨酯丙烯酸酯、聚酯聚醚丙烯酸酯和合氢化菲环结构的松香基光固化低聚物的研究现状,展望了含刚性环结构化合物在紫外光固化涂料方面的应用前景.     

Tunable filter and optical buffer based on dual plasmonic ring resonators

We demonstrate the realization of on chip plasmon-induced transparency using dual ring resonators coupling to metal–dielectric–metal bus waveguide. The theoretical results agree well with the finite-difference time-domain simulative ones. Moreover, by adjusting the radius, width, as well as the coupling distance can efficiently operate the wavelengths and bandwidths of our filter. In theory, we propose a feasible method to improve the trade-off between transmission and quality factor. Finally, the ultra-compact structure possesses slow light effect and manifests a low group velocity, which provides a guideline to control the light and has potential application in optical filter and optical buffer.     

Photonic highway switches based on ring resonators used as frequency-selective components

A new concept for a highway switch, which can be used to connect different optical wavelength division multiplexing data highways for data exchange, is proposed and the system relevant properties are outlined. For the required add-drop filter elements we used ring resonators. Typical characteristics of channel bandwidth, channel spacing, free spectral range, amplification, and cross-talk behavior of a highway switch with double-cavity ring resonators are basically examined and to some extent compared with solutions that were obtained with standard single-ring resonators. A signal flow chart transformation for evaluating filter transfer functions is presented.     

Versatile waveguide-coupled optofluidic devices based on liquid core optical ring resonators

A versatile waveguide-coupled optofluidic device using the liquid core optical ring resonator (LCORR) that can be operated with liquid of any refractive index (RI) is theoretically analyzed and experimentally demonstrated. The results confirm the confinement of resonant modes for all sample RIs, and reveal that confined modes in a high-RI core are excited by an external waveguide by resonant tunneling through the LCORR wall. It is further found that a thin wall must be used for effective interaction between the core mode and the waveguide. The results have important applications in optofluidic devices, including sensors, microfluidic lasers, and nonlinear optics.     

Analysis of thickness-extensional waves propagating in the lateral direction of solidly mounted piezoelectric thin film resonators

In a solidly mounted piezoelectric thin film resonator (SMR), acoustic waves propagate not only in the thickness direction but also in the lateral direction. In this study, we analyzed the acoustic wave in the SMR-type piezoelectric thin film resonator and derived the dispersion relation between the lateral wave number and frequency, considering wave propagation in the lateral direction. The lateral wave number was shown to be a complex number due to the leak of the acoustic energy to a substrate. It also was shown that the Q factor could be calculated from the complex cutoff frequency, and it becomes higher when the number of quarter-wave (lambda/4) layers increases. Using the dispersion relation, the trapped-energy resonant modes of an SMR were analyzed, considering the boundary conditions at the edge of the electrode.     

Improved coupling technique of ultracompact ring resonators in silicon-on-insulator technology

In order to improve the coupling coefficient between a bus waveguide and a bent waveguide of an ultracompact microring to obtain the critical coupling, a design using a bent bus waveguide with reduced width is provided to maintain a better phase matching and increase the coupling. A full vectorial finite difference model, specifically suited for high index contrast and smaller size waveguides, for example, a waveguide in the silicon-on-insulator (SOI) technology, is developed. As a validation, the straight and bent waveguides are simulated using this model, whose results are compared with the results deduced from the measurement results of the ultracompact ring resonators in SOI technology. Also, the model solver is performed to simulate the design, and an experiment is implemented to testify the design.     

Effect of fractal-matrix resonators on the properties of thin copper films

The effect of fractal-matrix resonators of AIRES type, situated outside the discharge zone, on the properties of thin (submicron) copper films obtained using magnetron ion sputtering is studied. Using the proposed technique, it is possible to obtain copper films of submicron thickness with local regions representing self-organized fractal structures.     

Modal analysis of ultra-compact channel filters based on race-track photonic crystal ring resonators

A new channel drop filter (CDF) is proposed based on a race-track photonic crystal ring resonator composed of square-lattice cylindrical silicon rods in air. By using a two-dimensional finite-difference, time-domain numerical technique, the modal behavior of two representative CDFs, parallel and perpendicular, has been analyzed. The analyses include the impact of additional scatterer size, scatterer amount and their position on the performance of proposed CDFs, such as drop efficiency and quality factor (Q). For the parallel CDF, about 130 spectral Q and 99% drop efficiency can be optimally achieved at 1363?nm channel with 0.145 periodicity scatterer size, whereas for the perpendicular one, about 180 spectral Q and 99% drop efficiency can be optimally obtained at 1366?nm channel with 0.165 periodicity scatterer size. By increasing the number of scatterers, the efficiency of both configurations can be enhanced. No obvious variation is obtained by changing the scatterer position.     

Analysis of coupling between two slab waveguides in the presence of ring resonators

The coupling phenomena between two slab waveguides in the presence of ring resonators are investigated through a rigorous integral equation analysis. A Green's-function-theory approach is utilized to develop the integral equation formulation. The solution is obtained by applying an entire-domain Galerkin technique, using the orthogonality properties of involved wave functions in the ring resonators. The field's transmission and reflection coefficients are accurately computed and a practical directional-coupler approach is discussed. The presented results reveal strong resonant coupling phenomena between the two waveguides and the resonators.     

Influence of a magnetic field on quartz crystal resonators

The magnetic sensitivity of quartz crystal resonators is a consequence of the ferromagnetic properties of the metal used as support for the vibrating plate. Various magneto-mechanic interactions can contribute to the overall sensitivity, the most important of which is shown to be the change in Young's modulus of the spring material submitted to a magnetic field, which in turn modifies the stress in the quartz plate and then induces a change in the crystal resonant frequency. The experimental setup and procedure are described and a large number of experimental results obtained with resonators of different technologies are presented and discussed. A comparison between the magnetic behavior of identical resonators mounted with different materials definitely proves the responsibility of the supports in the magnetic sensitivity of resonators and gives interesting information on its reduction     

Bifurcation and stability of structures with interacting propagating cracks

A general method to calculate the tangential stiffness matrix of a structure with a system of interacting propagating cracks is presented. With the help of this matrix, the conditions of bifurcation, stability of state and stability of post-bifurcation path are formulated and the need to distinguish between stability of state and stability path is emphasized. The formulation is applied to symmetric bodies with interacting cracks and to a halfspace with parallel equidistant cooling cracks or shrinkage cracks. As examples, specimens with two interacting crack tips are solved numerically. It is found that in all the specimens that exhibit a softening load-displacement diagram and have a constant fracture toughness, the response path corresponding to symmetric propagation of both cracks is unstable and the propagation tends to localize into a single crack tip. This is also true for hardening response if the fracture toughness increases as described by an R-curve. For hardening response and constant fracture toughness, on the other hand, the response path with both cracks propagating symmetrically is stable up to a certain critical crack length, after which snapback occurs. A system of parallel cooling cracks in a halfspace is found to exhibit a bifurcation similar to that in plastic column buckling.     

Design and properties of STW asynchronous resonators on quartz

In a surface transverse wave (STW) asynchronous resonator, grating phase shifters are placed between interdigital transducers and reflectors to obtain the incident and reflected waves in phase, and the resonance frequency is located near the center frequency of the reflectors. In this paper, the scattering matrix method is used for design of such resonators with one dominant longitudinal mode. At a frequency of about 509.5 MHz, insertion loss, and loaded and unloaded quality factors of about 6 dB, 5,300 and 11,000, respectively, were obtained. The measured and calculated parameters of this resonator are in good agreement. Design guidelines and comparison of synchronous and asynchronous resonators are presented. Compared to synchronous resonators, low spurious signals' level, location of the resonance frequency near the center frequency of the reflectors, and simple design method make the asynchronous resonators more attractive for manufacture and practical applications.