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Photonic crystals based on dielectric material with very high dielectric constant [variant_greek_epsilon] are investigated by transmission experiments in the microwave range and by calculations of the band structure and wave propagation. The material used is a tungsten-bronze-type ceramic (BaO–Nd2O3–4TiO2) with [variant_greek_epsilon]≈90. Our results demonstrate the superior properties of such a material, including omnidirectional and complete gaps, and improved waveguiding. This type of photonic crystals opens an additional road for basic research and applications regarding electronic devices in the radio frequency and microwave ranges as well as for spectroscopic techniques in the terahertz range. [ABSTRACT FROM AUTHOR]

This study was conducted to design a wideband septum polariser as a feeder of the antenna to generate right-hand circular polarisation (RHCP) and left-hand circular polarisation (LHCP) concurrently. The proposed septum polariser overcomes the conventional bandwidth limit and covers 40% bandwidth from 8 to 12 GHz. Moreover, a quad-ridged horn is chosen as a radiator of the feeding network due to its waveguide structure, wide bandwidth, and dual polarisation. Therefore, the proposed structure consists of a quad-ridged horn fed by a square waveguide, a waveguide transition, and a wideband septum polariser. The final design has an axial ratio <1.5 dB over the X-band. This configuration can be used as a feed for reflector antennas due to the wideband and dual polarisation characteristics. Furthermore, the structure is highly recommended for high-power applications because of its waveguide feature. [ABSTRACT FROM AUTHOR]

A single mode laser based on coupled cavities of an active ring laser and a Fabry Perot is presented. The laser exhibits tunable single mode behaviour with a side mode suppression ratio of 41 dB and a line-width of 400 kHz. [ABSTRACT FROM AUTHOR]

This paper presents the applicability of cavity modeling technique to analyze field propagation inside a multiport waveguide network. For a better understanding of the subject, we have considered a five-port quadraplexer as our target network. Field propagations within the network at different passband and stopband frequencies have been presented. The analysis has been verified by comparing the overall frequency response of the network with the available data in literature. The analysis demonstrates the field division at different junctions as well as field attenuation/propagation at different points of the network, which will be helpful for designing more complex and/or advanced multiport waveguide networks. It also demonstrates the presence of higher order modes at different discontinuities of the network and their effects on the respective field distributions. [ABSTRACT FROM AUTHOR]

We present a novel electromagnetic bandgap (EBG) structure, which can be used to manufacture low-cost waveguiding structures at high frequencies. The unit cell of the proposed EBG consists of glide-symmetric holes in parallel plate waveguide. Using this unit cell in groove gap waveguide technology has a number of advantages over pin-type EBG at high frequencies, such as acquiring higher accuracy because of larger periodicity as well as an easier and cheaper manufacturing process. The performance of the proposed waveguiding structure is demonstrated using both a straight and a double 90° bent lines through simulation and measurement. [ABSTRACT FROM PUBLISHER]

Integrated electric-field (E-field) sensors are commonly used devices in E-field sensing. However, distortion in the modulated signal due to high half-voltage (Vπ) and obtaining a low-frequency response are challenging issues in low-frequency AC E-field sensors. The aim of this study is to investigate a modification by adding a Si layer beneath a segmented slot waveguide (SSW) and optimizing the hybrid SSW as the core of a sensor to determine the sensor features in terms of the frequency response and sensitivity. The results of reducing the Si-layer thickness and segment width with high periodicity revealed a high modulation efficiency for very low-frequency AC E-field sensors and simultaneously expanded the minimum limit of detection by incorporating sensors in very small AC E-fields. This study validated the feasibility and efficiency of using a hybrid SSW as the core of highly sensitive low-frequency AC E-field sensors. [ABSTRACT FROM AUTHOR]

A tetrahedron meshing and transforming method for 3-D implementation of transformation optics is proposed and verified for a few waveguide components. The method is applicable to a wide range of electromagnetic problems. An important feature of the proposed method is that the transformed medium will be piecewise homogeneous and free of any singularities. In this method, the region under transformation is divided into a few tetrahedrons, both in the physical and virtual domains. Each tetrahedron of the physical domain transforms to a tetrahedron in the virtual domain. The material properties of each tetrahedron are then calculated using the Jacobean matrix of the transformation. Since the elements of the Jacobean matrix are constant, the $\varepsilon$ and $\mu$ tensors are finite and homogeneous in each tetrahedron. The method is verified for several rectangular waveguide coupler examples. Features of the $\varepsilon$ and $\mu$ tensors of the discussed examples are described. For instance, it is shown that the material properties may reduce to 2-D material types, or material anisotropy may reduce, under certain conditions. [ABSTRACT FROM AUTHOR]

Design guidelines for a guided-wave optical pressure sensor based on dependences of sensitivity and resonance frequency on diaphragm dimensions were considered. The guided-wave optical pressure sensor consists of a diaphragm and a single-mode waveguide on the diaphragm. According to our theoretical study, the edge of the diaphragm was found to be the best position to obtain the highest sensitivity. Also, sensitivity is proportional to the cube of the side length of the diaphragm but inversely proportional to the square of the diaphragm thickness. On the other hand, resonance frequency of the diaphragm is proportional to the diaphragm thickness and inversely proportional to the square of the side length. Dependences were experimentally examined for fabricated sensors with different diaphragm dimensions to confirm theoretical predictions. The experimental results agreed well with the theoretical predictions. Moreover, a design assistant chart for the sensor was proposed based on the dependences. [ABSTRACT FROM AUTHOR]

This paper reports the design, fabrication, and characterization of a fully 3-D printed waveguide (WG) and a microfluidically controlled WG switch, operating at K-band. The WG body is printed using a benchtop 3-D printer with thermoplastic substrate acrylonitrile butadiene styrene, and the conductive layer is incorporated using the same printer by automated deposition of conductive silver ink. The measured total insertion loss of the 3-D printed WG is in good match with the simulations showing better than 0.11 dB/cm for the entire K-band. The 3-D printed WG is characterized, and its attenuation and propagation constants are computed for the K-band using a multiline technique. In addition, microfluidically controlled eutectic gallium–indium and galistan liquid metals are integrated with the 3-D printed WG, and a novel reflective WG switch is implemented. The insertion loss and isolation of the switch are measured to be better than 0.5 dB and better than 15 dB for the entire K-band, respectively. Furthermore, the switch’s performance with respect to changes in ambient temperature has been studied. To the best of our knowledge, this is the first time that fused deposition modeling printing and automated ink dispensing is used to fabricate fully 3-D printed WGs, and a 3-D printed WG switch is developed, exhibiting the potential of such technology for rapid prototyping of RF devices. [ABSTRACT FROM PUBLISHER]

The systematic design, fabrication, and characterization of an isolated, single-mode, 90° bend phononic crystal (PnC) waveguide are presented. A PnC consisting of a 2D square array of circular air holes in an aluminum substrate is used, and waveguides are created by introducing a line defect in the PnC lattice. A high transmission coefficient is observed (-1 dB) for the straight sections of the waveguide, and an overall 2.3 dB transmission loss is observed (a transmission coefficient of 76%) for the 90° bend. Further optimization of the structure may yield higher transmission efficiencies. This manuscript shows the complete design process for an engineered 90° bend PnC waveguide from inception to experimental demonstration. [ABSTRACT FROM AUTHOR]

This communication demonstrates experimentally the improvement in axial ratio performance when a slot is combined with a set of three parasitic dipoles instead of one. The analysis is performed in the context of slotted-waveguide arrays and SATCOM applications in Ka band, where a bandwidth specification as wide as 7.5% can be demanded. [ABSTRACT FROM AUTHOR]

ABSTRACT A perpendicular E-plane transition between rectangular waveguide (WG) and suspended stripline (SSL) in the Ku-band is presented. The topology of coupling network is studied and design guidelines are provided. A 10-dB return loss bandwidth (BW) of 12% was obtained using a patch resonator on a double-sided single-layer dielectric substrate combined with a cavity behind the resonator of a very shallow depth as low as 1 mm for a compact design. An insertion loss of 0.18 dB at 13.8 GHz was achieved in the measurement of a back-to-back SSL-WG-SSL transition. Comparison of the measured performances with the state-of-the-art WG transitions to SSL shows a 1.5 times improvement in frequency bandwidth and a three times reduction in electrical dimensions. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1831-1834, 2016 [ABSTRACT FROM AUTHOR]

In this paper, we propose and simulate a pressure sensor based on two-dimensional photonic crystal with the high quality factor and sensitivity. The sensor is formed by the coupling of two photonic crystal based waveguides and one nanocavity. The photonic crystal with the triangular lattice is composed of GaAs rods. The detailed structures of the waveguides and nanocavity are optimized to achieve better quality factor and sensitivity of the sensor. For the optimized structures, the resonant wavelength of the sensor has a linear redshift as increasing the applied pressure in the range of 0-2 GPa, and the quality factor keeps unchanged nearly. The optimized quality factor is around 1500, and the sensitivity is up to 13.9 nm/GPa. [ABSTRACT FROM AUTHOR]

We propose a light delivery system to the near-field transducer (NFT) of a heat-assisted magnetic recording (HAMR) head using a Mach–Zehnder interferometer (MZI) waveguide arrangement with a transverse electric (TE) mode coupled to the planar waveguide from a single mode fiber. The proposed design offers great flexibility in the coupling of light to the NFT in order to match the desired radiation pattern of the antenna and thus to optimize the energy transfer. Furthermore, it allows excitation of particular surface plasmon (SP) resonances of the transducer (quadrupole or higher) by controlling the coupling angle and the phase of the two beams of light. The optimum phase shift between the TE waveguide modes incident on the NFT can be achieved either statically by making one of the MZI arms longer/shorter compared with the other one, or dynamically by changing the mode effective index of the MZI waveguide arm through electro-optic or thermo-optic modulation. In addition, the proposed MZI waveguide arrangement enables easier coupling from a laser with coupling losses from laser to MZI waveguide being below 3 dB and the design enables an arrangement of the NFT placed either on the top of the waveguide at the termination side of the MZI or between the rib and the ridge at the maximum of the electric field of the waveguide, which maximizes the SP resonance enhancement of the NFT. Another advantage is that the magnetic-write pole, in our design, can be easily integrated on the same chip, preferably above the center of the MZI, between the two arms of the interferometer and away from the propagating mode, thus avoiding blocking of the light path. [ABSTRACT FROM AUTHOR]

A type of low-barrier Schottky barrier diode (SBD), based on InGaAs/InP, is designed and fabricated, and then a 340-400 GHz zero-biased waveguide detector utilizing this diode is proposed. To predict the performance of the SBD, firstly we present a self-consistent analytical method to find the accurate values of the parameters of the SBD by using the on-wafer measured S-parameter under different bias conditions up to 40 GHz and an auxiliary de-embedding structure. The extracted values show a very good agreement with the theoretical values. Then a concept called effective capacitance is proposed to model the high frequency (340-400 GHz) properties of the SBD. This concept has greatly improved the consistency of the simulated and measured results of the detector. The measured maximum voltage responsivity and the minimum noise effective power (NEP) of the detector are 800 mV/mW and 3.46×10-11 W/Hz0.5 at 382 GHz, respectively. [ABSTRACT FROM AUTHOR]

In this paper, the tuning characteristics of band gaps and waveguides in a locally resonant phononic crystal structure, consisting of multiple square stubs deposited on a thin homogeneous plate, are investigated. Using the finite element method and supercell technique, the dispersion relationships and power transmission spectra of those structures are calculated. In contrast to a system of one square stub, systems of multiple square stubs show wide band gaps at lower frequencies and an increased quantity of band gaps at higher frequencies. The vibration modes of the band gap edges are analyzed to clarify the mechanism of the generation of the lowest band gap. Additionally, the influence of the stubs arrangement on the band gaps in multi-stub systems is investigated. The arrangements of the stubs were found to influence the band gaps; this is critical to understand for practical applications. Based on this finding, a novel method to form defect scatterers by changing the arrangement of square stubs in a multi-stub perfect phononic crystal plate was developed. Defect bands can be induced by creating defects inside the original complete band gaps. The frequency can then be tuned by changing the defect scatterers' stub arrangement. These results will help in fabricating devices such as acoustic filters and waveguides whose band frequency can be modulated. [ABSTRACT FROM AUTHOR]

We present a Slot waveguide design for dispersion compensation at 1538 nm wavelength. The design is based on a coupled strip slot waveguide with a strip slot separation of air medium. Resonance between the strip waveguide and slot waveguide has been utilized to achieve high dispersion. The simulation and analysis of design has been carried out by finite difference time domain method. Resonance between strip and slot mode results in a high negative dispersion of −4.8 × 10 ps/km-nm over an full width at half maximum bandwidth of 13 nm at 1538 nm centre wavelength. The resonance wavelength and magnitude of the dispersion can be fine tuned by varying the parameters strip width, slot width, and strip slot separation. Such a waveguide structure should find applications in the design of integrated-optic dispersion compensators for optical telecommunication and ultrafast waveguide lasers. [ABSTRACT FROM AUTHOR]

A generic methodology for constructing complex integrated electro-optic circuits in waveguided configurations is presented. The method is based on combining two techniques, 'laser ablation' and 'refractive index engineering by ion implantations.' The constructed circuits are side-cladded by air trenches that were produced using laser ablation and bottom-cladded by a layer with a reduced refractive index which is generated through the implantation of He ions. This fabrication technique enables the construction of circular structures with complex geometry featuring small radii of curvature, and further can be employed to construct microfluidic channels on the same substrate. The research demonstrates waveguides in both linear and circular configurations that were constructed in a potassium lithium tantalate niobate (KLTN) substrate using the aforementioned method, proving that this substrate is a suitable candidate for use in creating laboratories-on-a-chip with multifunctional capabilities. The proposed techniques used in the research are generic and applicable to a wide range of substrates. [ABSTRACT FROM AUTHOR]

Surface plasmon polariton wave propagation in a pyramidal 3D nanostructural waveguide carved in silver substrate is numerically studied by using FDTD method. Maximum field enhancement of 97 dB is obtained by using such structure which is enough to initiate high harmonic generation process. Furthermore, three times increase in amplification volume is acquired as compared with other geometries, which make the process of high harmonic generation more feasible. Moreover, effect of the polarization of the incident beam on field enhancement is also numerically investigated. [ABSTRACT FROM AUTHOR]

A new low-pass waveguide filter topology is proposed based on capacitive posts using rounded shapes. The new structure is designed using a technique that benefits from a full-wave integral equation simulation tool for arbitrarily shaped capacitive microwave circuits. This integral equation method enables one to apply an efficient filter design technique employing iris geometries other than rectangular discontinuities, such as the one based on rounded posts proposed in this work. A prototype using circular posts has been manufactured and measured obtaining excellent results as compared with predictions, thus demonstrating the practical feasibility of the new proposed filtering structure. A new filter using elliptic capacitive posts was compared in terms of multipactor risk against similar filters based on traditional rectangular windows and on rectangular posts. Simulation results indicate that the new proposed concept using rounded shapes leads to geometries that can double multipactor thresholds as compared with traditional filters. [ABSTRACT FROM AUTHOR]

ABSTRACT The article describes practical guidelines for an E-Band tuning-less waveguide diplexer design (71-86 GHz) which requires looser fabrication tolerances and provides higher yield than traditional methods. Physical considerations concerning sensitivity to manufacturing inaccuracies are discussed and proven by designing and manufacturing two different diplexers on a set of typical specifications. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:508-512, 2014. [ABSTRACT FROM AUTHOR]

A wide-beam waveguide circularly polarized antenna is designed at Ka band in this paper, in which a linearly polarized wave is transformed into a circularly polarized wave through an elliptical and gradual change waveguide structure. The design model is simulated and optimized in 3D electromagnetic simulation software HFSS.14. Simulation results show that the 3 dB beam-width is greater than 80° (±40°) and the axial ratio is less than 3 dB in this beam, the total gain is about 9 dB, and the voltage standing wave ratio is less than 1.47 in 32–38 GHz. Measured results are in good agreement with the simulation results; the antenna performance meets the design requirements. [ABSTRACT FROM AUTHOR]

A method for determining the complex anisotropic permittivity for electrically small material specimens of complex shape with biaxial dielectric anisotropy is described and representative measured results are presented. The method extracts the anisotropic tensor elements from specimen reflection measurements made with a shorted rectangular waveguide. A number of independent reflection measurements, using different specimen orientations in the waveguide equal to the number of unknown permittivity terms, are required. The specimens need not fill either dimension of the waveguide cross section and are permitted to be electrically short in the propagation direction. Measurements using WR1500 and WR1150 waveguide were made for a known isotropic low-loss dielectric specimen of complex shape. Additional measurements in WR1500 were made on two engineered anisotropic artificial dielectric specimens. Tensor permittivity elements were extracted from the measurements and were used to validate and demonstrate the accuracy and capability of the method by comparison with known values for the dielectric specimen or with explicit inclusion-binder simulation results for the engineered specimens. [ABSTRACT FROM PUBLISHER]

In this paper, a method to design high-power low-pass harmonic filters in rectangular waveguide technology is proposed. The new filters consist of a collection of smooth E-plane bandstop elements along the propagation direction and a smooth variation of the filter width. This yields to a broad rejected band for the fundamental TE10 mode, together with higher-order (TEn0 and non-TEn0) mode suppression. Two different examples with stringent requirements of the space industry are provided to demonstrate the capabilities of the new methodology. By means of high-power simulations and an extensive measurement campaign, it will be shown that the smoothness of the filter profile guarantees high-power operation even with small minimum mechanical gaps. Moreover, unlike classical techniques, our method is not restricted to filters with small gaps. Hence, filters with larger gaps (always fulfilling the demanding frequency specifications) are fabricated for even higher power-handling performance. [ABSTRACT FROM AUTHOR]

The propagation of surface waves along spatially dispersive graphene-based 2-D waveguides is investigated in detail. Graphene is characterized using a full-k_\rho conductivity model under the relaxation-time approximation, which allows to obtain analytical and closed-formed expressions for the wavenumber of plasmons supported by sheets and parallel plate waveguides, respectively. Per unit length equivalent circuits are introduced to accurately characterize the propagation in different waveguides, and analytical relations between the effective TM-mode circuit lumped elements and graphene conductivity are derived. The proposed circuits allow identifying the different mechanisms involved in spatially dispersive plasmon propagation, explaining their connection with the intrinsic properties of graphene. Results demonstrate that spatial dispersion, which significantly decreases the confinement and the losses of slow surface plasmons, must be accurately assessed in the design of graphene-based plasmonic components at millimeter-waves and low terahertz frequencies. [ABSTRACT FROM AUTHOR]

We present a technology for the manufacturing of silicon-filled integrated waveguides enabling the realization of low-loss high-performance millimeter-wave passive components and high gain array antennas, thus facilitating the realization of highly integrated millimeter-wave systems. The proposed technology employs deep reactive-ion-etching (DRIE) techniques with aluminum metallization steps to integrate rectangular waveguides with high geometrical accuracy and continuous metallic side walls. Measurement results of integrated rectangular waveguides are reported exhibiting losses of 0.15 dB/\lambda{{g}} at 105 GHz. Moreover, ultra-wideband coplanar to waveguide transitions with 0.6 dB insertion loss at 105 GHz and return loss better than 15 dB from 80 to 110 GHz are described and characterized. The design, integration and measured performance of a frequency scanning slotted-waveguide array antenna is reported, achieving a measured beam steering capability of 82 ^\circ within a band of 23 GHz and a half-power beam-width (HPBW) of 8.5^\circ at 96 GHz. Finally, to showcase the capability of this technology to facilitate low-cost mm-wave system level integration, a frequency modulated continuous wave (FMCW) transmit-receive IC for imaging radar applications is flip-chip mounted directly on the integrated array and experimentally characterized. [ABSTRACT FROM PUBLISHER]

In this article, the authors study the significant practical effects caused by the presence of a conductor plate beneath a coplanar waveguide (CPW) structure. Specifically the authors pay attention to the effects on the dispersion characteristics of the bound modes and on the signal integrity. This study allows one to discuss the reported proposal on the use of this additional conductor plate as an inexpensive alternative to air-bridges in order to alleviate the possible spurious effects produced by the potential existence of asymmetries in CPW-based circuits. [ABSTRACT FROM AUTHOR]

In this article, finite element analysis and fabrication of a horn-type megasonic waveguide for nanoparticle cleaning is carried out. To design the megasonic system, the impedance graph of the megasonic waveguide is analyzed using the finite element method software ANSYS. The predicted antiresonance frequency of the piezoelectric actuator used in the system is 1003 kHz, which agrees well with the measured value of a manufactured piezoelectric actuator 1005 kHz. In addition, the antiresonance frequency of a quartz waveguide with the lead zirconate titanate actuator is predicted as 1001 kHz, which also agrees well with the experimental data of 1003 kHz. Acoustic analysis to predict the acoustic pressure distribution of the waveguide is performed, and well distributed pressures in water is observed at the end of the waveguide. Also, the acoustic pressure of the developed quartz waveguide is measured and compared with that of a commercial megasonic system having 1 MHz operating frequency. The quartz waveguide system provides a 25% more acoustic pressure output. In addition, the standard deviation is decreased by 27%. Finally, a particle removal efficiency test shows over 91% particle removal after cleaning. These results suggest that the horn-type megasonic waveguide can be applied to the nanoparticle cleaning process. [ABSTRACT FROM PUBLISHER]

The non-reciprocal phase shifter in the design of the waveguide differential phase-shift circulator consists of two or four suitably magnetised ferrite tiles on the top and bottom walls of the waveguide. It may be adjusted in terms of a reciprocal condition and a non-reciprocal one. The first condition essentially fixes the geometry of a typical phase-shift section except for the thickness of each ferrite tile; the second determines the connection between the split-phase constants and the thickness of the tiles for parametric values of gyrotropy. The purpose here is to satisfy the first requirement of the two-tile geometry using a calculation and to meet the second one by having recourse to measurements. It includes some preliminary experimental data on new four- and eight-stacked ferrite tile structures. It is likely to prove of value in the design of large continuous wave power devices. [ABSTRACT FROM AUTHOR]

Abstract: We present a semi-analytic method to calculate the dispersion curves and the group velocity of photonic crystal waveguide modes in two-dimensional geometries. We model the waveguide as a homogenous strip, surrounded by photonic crystal acting as diffracting mirrors. Following conventional guided-wave optics, the properties of the photonic crystal waveguide may be calculated from the phase upon propagation over the strip and the phase upon reflection. The cases of interest require a theory including the specular order and one other diffracted reflected order. The computational advantages let us scan a large parameter space, allowing us to find novel types of solutions. [Copyright &y& Elsevier]

A numerical model for predicting the multipactor breakdown effect in wedge-shaped hollow waveguides is presented in this paper. The computation of electromagnetic fields is based on the boundary integral–resonant mode expansion method, which provides the modal chart of hollow waveguides with any arbitrary cross section. The advantage of using wedge-shaped waveguides with respect to conventional rectangular ones is the deviation of the resonant paths of the electrons toward regions with lower voltages, thus reducing the probability of multipactor threshold for certain input power. To validate this method, our results have been compared with simulations from previous theoretical studies. Once the simulation tool is validated, it is used to predict the multipactor threshold of wedge-shaped waveguides with different symmetric inclination angles of their horizontal plates. Finally, susceptibility curves as the ones already available for rectangular waveguides are presented. These charts are useful for designing innovative waveguide geometries with improved multipactor-free working power ranges. [ABSTRACT FROM AUTHOR]

The article focuses on the waveguide optical light beam deflector that uses thermooptic (TO) or electrooptic (EO) effect. It mentions that waveguide deflectors are implemented through evanescent coupling and EO prism. It discusses the structure of deflectors which consist of a Y-shaped waveguide with electrodes coupled to a slab waveguide for fast deflection. It states that an electrode on each arm of Y-shaped waveguide will control the refractive index of the refraction.

The propagation of electromagnetic waves is reconsidered in the context of cylindrical tunnels through material of uniform electrical properties. In the absence of internal conductors, the wave solutions reduce to well-known analytic expressions, requiring the solution of a single transcendental equation in complex phase space. Any given tunnel configuration has a wide range of solutions in phase and frequency space. Identifying these solutions can be a significant numerical challenge. Both the Newton-Raphson method and the winding number technique have been described in previous publications, and each can be prone to missing solutions. This paper reviews these two solution techniques and develops a combination of the two to provide a fast and efficient procedure for locating the roots in well-defined regions of phase space. [ABSTRACT FROM AUTHOR]

We study numerically and analytically a binary mixture of quantum dots exhibiting gain and loss. For a mixture of gain quantum dots and silver nanoparticles, we find conditions when the composite shows negative dielectric constant operation and lossless operation. The composites of this kind may be used for dense integration of photonic components as well as modulation and switching in optical interconnect systems [ABSTRACT FROM AUTHOR]

An optical backplane based on a meshed polymer waveguide architecture enabling high-speed board-to-board optical interconnection is presented. This planar array of multimode polymer waveguides can provide passive strictly non-blocking links between server line cards fitted with optical transmitter and receiver arrays. This architecture offers a scalable and low-cost solution to the bandwidth limitations faced by electrical backplanes and is suitable for PCB integration. The reported backplane demonstrator uses a matrix of 100 waveguides each capable of 10 Gb/s operation to interconnect 10 cards for a total capacity of a terabit per second aggregate data rate in multicast mode. Characterisation of the backplane demonstrator reveals low link losses of 2 to 8 dB for a multimode fibre input and crosstalk values below −35 dB. Error free data transmission at 10 Gb/s is achieved with a power penalty of only 0.2 dB at a bit-error-rate of 10−9. Additionally, lossless operation of a Gigabit Ethernet link over the backplane is achieved even when using the worst-case highest loss links. [ABSTRACT FROM AUTHOR]

We report that completely athermal design of a slotted silicon waveguide is possible by combining the negative thermo-optic (TO) coefficient of, for example, polymethyl methacrylate (PMMA) with the positive TO coefficient of silicon. When used in a microring resonator structure, the filled overcladding slotted waveguide and the unfilled (air-filled) overcladding slotted waveguide can both achieve athermal characteristics. Simulations indicate a wide range of realizations with proper design parameters of the slotted waveguides, namely, the silicon strip and slot widths. Preliminary experimental results on fabricated devices demonstrate that the temperature dependence is reduced from 91 pm/°C for a regular microring resonator to 52 pm/°C for the PMMA-clad microring resonator. Completely athermal realization is expectable in similar devices with improved fabrication techniques. For the external optical source, we demonstrate a stable 3.5 THz wide (175 modes×20 GHz) optical comb source with nearly flat spectral phase. Adjustable mode spacing and wavelength tunability across the C-band are maintained so that comb lines can be matched to the specified wavelength grid of the computing system. With such schemes, temperature controls of individual optical components in the optically interconnected computing chips become unnecessary, greatly reducing the complexity of the computing system. [ABSTRACT FROM AUTHOR]

We discuss the recently developed hybrid silicon evanescent platform (HSEP), and its application as a promising candidate for optical interconnects in silicon. A number of key discrete components and a wafer-scale integration process are reviewed. The motivation behind this work is to realize silicon-based photonic integrated circuits possessing unique advantages of III–V materials and silicon-on-insulator waveguides simultaneously through a complementary metal-oxide semiconductor fabrication process. Electrically pumped hybrid silicon distributed feedback and distributed Bragg reflector lasers with integrated hybrid silicon photodetectors are demonstrated coupled to SOI waveguides, serving as the reliable on-chip single-frequency light sources. For the external signal processing, Mach–Zehnder interferometer modulators are demonstrated, showing a resistance-capacitance-limited, 3 dB electrical bandwidth up to 8 GHz and a modulation efficiency of 1.5 V mm. The successful implementation of quantum well intermixing technique opens up the possibility to realize multiple III–V bandgaps in this platform. Sampled grating DBR devices integrated with electroabsorption modulators (EAM) are fabricated, where the bandgaps in gain, mirror, and EAM regions are 1520, 1440 and 1480 nm, respectively. The high-temperature operation characteristics of the HSEP are studied experimentally and theoretically. An overall characteristic temperature ( T0) of 51°C, an above threshold characteristic temperature ( T1) of 100°C, and a thermal impedance ( Z T) of 41.8°C/W, which agrees with the theoretical prediction of 43.5°C/W, are extracted from the Fabry–Perot devices. Scaling this platform to larger dimensions is demonstrated up to 150 mm wafer diameter. A vertical outgassing channel design is developed to accomplish high-quality III–V epitaxial transfer to silicon in a timely and dimension-independent fashion. [ABSTRACT FROM AUTHOR]

Hollow metal waveguides feature well collimated beams and small losses across air gaps. This enables introduction of multiple optical beam splitters, or taps, along the waveguide to multicast signals from a source to multiple receivers. The splitters need to be of sufficient thickness to provide mechanical integrity and ease of handling. As a result, passing through the thickness leads to a beam walk-off. Walk-off dependence on the splitter thickness and its effect on the system optical efficiency are investigated. Two methods to compensate the walk-off are described: by offsetting the outgoing waveguide, and by introducing an additional symmetric optical element to shift the beam back to the original optical path. Both methods have been shown to effectively mitigate the walk-off effects. [ABSTRACT FROM AUTHOR]

As data rates continue to increase in high-performance computer systems and networks, it is becoming more difficult for copper-based interconnects to keep pace. An alternative approach to meet these requirements is to move to optical-based interconnect technologies which offer a number of advantages over the legacy copper-based solutions. In order to meet the stringent requirements of high performance and low cost, manufacturable waveguide technologies must be developed. Past solutions have often employed polymer waveguide technologies, which can be expensive and limited by modal dispersion. In the present work, hollow metal waveguides (HMWGs) are investigated as a potential alternative. These waveguides demonstrate very low optical losses of <0.05 dB/cm and the capability to transmit at extremely high data rates. The fabrication, modeling, characterization of the HMWGs are discussed to enable photonic interconnect solutions for future generations of computer and server products. [ABSTRACT FROM AUTHOR]

In this paper, we studied ZnO-based film bulk acoustic resonator (FBAR) device fabricated on a specially designed multilayered Bragg reflector part. Very thin chromium adhesion layers (0.03 μm thick) were additionally deposited to improve the quality of the Bragg reflector and some thermal treatments were performed to improve the resonant characteristics of the FBAR device. At the operating frequency of ∼2.7 GHz, excellent resonant characteristics were observed in terms of return loss and quality factor, and effective electromechanical coupling coefficient. [ABSTRACT FROM AUTHOR]

A simple method for a Q-band planar triple-mode filter with quasi-elliptic function response is proposed in this letter. This filter is implemented using a high-order mode cavity with substrate-integrated waveguide (SIW) technology and standard printed circuit board (PCB) process. By adopting an orthogonal input and output feed-line and introducing some perturbation, transmission zeros are generated on both sides, which have significantly improved filter selectivity and out-of-band rejection. This triple-mode resonator is then combined with a circular dual-mode cavity to obtain a highly selective filter in Q-band with better stopband rejection. Both of the two filters are fabricated and measured. Low insertion loss and sharp sideband characteristic are observed, which is in good agreement with simulation. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 600–603, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24114 [ABSTRACT FROM AUTHOR]

In this work, a new type of wideband coplanar bandpass filter with sharp skirts and large stopband is proposed. The filter exhibits a flat response in the passband, and a steep slope and a high rejection in the stopband. The filter design is based on the use of a broadside-coupled (BC) coplanar-waveguide (CPW) directional coupler as a transversal filtering section (TFS). This is performed by conveniently loading two ports of the coupler with shunt stubs, so that the signals in the output port interfere in a way that a bandpass filter response is obtained. The suggested filter scheme has been validated experimentally throughout the design, fabrication, and measurement of a wideband coplanar bandpass filter centered at 2.0 GHz, formed by two TFS connected in cascade. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 294–298, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24029 [ABSTRACT FROM AUTHOR]

A square monopole coplanar antenna with a circular base is proposed for ultra wideband (UWB) communications. The design parameters are analyzed and optimized to obtain a good performance and the measured return loss below -10 dB is from 2.8 to over 40 GHz. The proposed antenna has advantages of low profile, small size, UWB, and omni-directional pattern. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 408–411, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24062 [ABSTRACT FROM AUTHOR]

An extreme wideband tapered slot antenna (TSA) fed by coplanar waveguide (CPW) for wideband applications is presented. A novel logarithmic flare slot and a double-Y balun are introduced into the design of the antenna. The experimental results demonstrates that this antenna achieves a ratio impedance bandwidth of 21.6 : 1 for VSWR ≤ 2 from 1.19 to 25.8 GHz, exhibits good end-fire patterns and moderate gains in the measured bandwidth from 1.2 to 13 GHz. The coplanar design, CPW feeding technique makes it easy for the integration of the antenna into circuit boards. [ABSTRACT FROM AUTHOR]

In order to perform robust millimeter-wave S parameter measurements of integrated circuits, and to connect them to standard measurement equipment, a transition from microstrip to the WR 12 standard rectangular waveguide is requested. This paper proposes a new millimeter-wave microstrip to the standard WR 12 rectangular waveguide (RWG) transition by the bias of an intermediary Substrate Integrated Waveguide (SIW). The SIW technology allows wide-band and high performance circuit fabrication and enables robust transition between planar integrated circuits and standard waveguides. Commercial Finite Element Method Software, High Frequency Structure Simulator (HFSS) was used to perform the design and the optimization in term of return and insertion loss. [ABSTRACT FROM AUTHOR]

A compact broadside coupled (BSC) backward directional coupler based on composite right/left-handed (CRLH) coplanar waveguide (CPW) is proposed. The design is symmetric on both sides of the substrate and comprises of series gap capacitor, broadside-coupled capacitor, and shunt meandering short-circuited stub inductor. Compared to existing directional couplers, the proposed coupler has much smaller size, broader bandwidth, phase balance and easy fabrication. An equivalent circuit model including series inductance, capacitance, shunt inductance and capacitance tank has also been established. Good agreement between the full-wave simulation and equivalent circuit model verifies the effectiveness of the proposed circuit model. Measured bandwidth from 9.9 ∼ 14.7 GHz centered at 12 GHz (40%) is observed with the device size of 1.8 × 1.3 cm2. [ABSTRACT FROM AUTHOR]

This paper presents, for the first time, the analysis and design performance of tunable left handed coplanar waveguide transformer designed on a ferrite substrate. The proposed transformer is studied analytically and verified numerically. Results show that the proposed transformer has tunable dual band of operation with frequency tuning range from 2.35 GHz to 3.85 GHz with return loss from 10 dB to 25 dB. Such tunability can be achieved by changing the DC magnetic bias. The advantages of the proposed transformer are its tuning capability, its multi functionality operation, and its compact size. [ABSTRACT FROM AUTHOR]

Abstract-A novel substrate integrated waveguide (SIW) multibeam antenna based on the parabolic reflector principle is proposed and implemented at 37.5 GHz, which takes the advantages of low loss, low profile, high gain, and mass producible. A prototype of the proposed antenna with seven input ports generating a corresponding number of output beams is fabricated in a standard PCB process. The measurements are in good agreement with the simulations, and the results demonstrate that this type of printed multibeam antenna is a good choice for communications applications where mobility and high gain are simultaneously required. [ABSTRACT FROM AUTHOR]

A numerical analysis is presented about the performance of non-collinear acousto-optic interaction in LiNbO3 guiding structures. To get the optimal design for a higher diffraction, the SAW power required for 100% diffraction (P100) dependences on the length of acousto-optic (AO) interactions, guided optical mode, waveguide depth and driving frequency are investigated. Some valuable results are obtained for design of guided-wave acousto-optic devices. [ABSTRACT FROM AUTHOR]