Comparative study of the integration density for passive linear planar light-wave circuits based on three different kinds of nanophotonic waveguide

A theoretical analysis and comparison of the integration density are given for passive planar lightwave circuits based on three different kinds of nanophotonic waveguide, namely, photonic crystal waveguides, Si nanowire waveguides, and nanoslot waveguides. Two criteria for determining the integration density are used. One is the minimal decoupled separation between two parallel nanophotonic waveguides, and the other is the area occupied by a low-loss 90 degree turn. Some important functional components (such as Y branches and optical add-drop filters) are also chosen as basic elements to evaluate the integration density. It is shown that the integration densities of passive linear planar lightwave circuits based on these three kinds of nanophotonic waveguide are comparable.     

Asymmetric light transmission based on coupling between photonic crystal waveguides and L1/L3 cavity

A compact design of all-optical diode with mode conversion function based on a two-dimensional photonic crystal waveguide and an L1 or L3 cavity is theoretically investigated. The proposed photonic crystal structures comprise a triangular arrangement of air holes embedded in a silicon substrate. Asymmetric light propagation is achieved via the spatial mode match/mismatch in the coupling region. The simulations show that at each cavity’s resonance frequency, the transmission efficiency of the structure with the L1 and L3 cavities reach 79% and 73%, while the corresponding unidirectionalities are 46 and 37 dB, respectively. The functional frequency can be controlled by simply adjusting the radii of specific air holes in the L1 and L3 cavities. The proposed structure can be used as a frequency filter, a beam splitter and has potential applications in all-optical integrated circuits.     

Wideband and low dispersion slow-light waveguide based on a photonic crystal with crescent-shaped air holes

We present a procedure to generate slow light with a large group index, wideband, and low dispersion in our suggested photonic crystal waveguide. By modulation of the declinations in the first two rows of air holes, the group index, the bandwidth, and the dispersion can be tuned effectively. Utilizing the two-dimensional plane wave expansion method (PWE) and the finite-difference time-domain method (FDTD), we demonstrate slow light with the group indices of 23, 35, and 45, respectively, while restricting the group-index variation within a 10% range. We accordingly attain an available bandwidth of 40.7, 23.7, and 5.1?nm, respectively. Meanwhile, the normalized delay-bandwidth product stays around 0.45, with minimal dispersion less than 0.2 (ps²/m) for all the cases.     

Design for additive manufacturing (DfAM) methodologies: a proposal to foster the design of microwave waveguide components

ABSTRACT

Additive manufacturing offers many advantages, especially in terms of creativity and design freedom. However, this emerging technology is disrupting the way design is carried out and creativity is often limited by the cognitive barriers installed through years of traditional manufacturing processes. Likewise, as this manufacturing process is relatively recent and quite unknown to designers, its specificities are not always considered during the design phase, which leads to manufactured parts happening to differ from CAD models in terms of sizing or surface quality. Consequently, microwave components nowadays manufactured layer-by-layer do not exhibit operational electromagnetic performances. In this way, it is necessary to guide designers throughout the development of a product by drawing their attention to the different steps they must consider in order to design an additive manufactured optimised part.     

In situ microwave characterisation of medium-k hfo2 and high-k srtio3 dielectrics for metal-insulator-metal capacitors integrated in back-end of line of integrated circuits

Integration of high permittivity dielectrics or commonly named high-k dielectrics is widely investigated as a way to reduce passive component size in the chip. The complex permittivity microwave characterisation of medium-k materials such as HfO₂ and high-k materials such as SrTiO₃ is presented. The characterisation method, using coplanar, microstrip waveguides or metal ?insulator?metal (MIM) capacitor, allows a large band characterisation, from 40 MHz to 40 GHz. It also allows investigating these materials with a large-scale thickness, from 10 up to 500 nm, in different technological configurations, appropriate for insulators from immature to mature, that is, those which are ready for the integration in an advanced damascene architecture of MIM capacitor. It is shown that the permittivity of such materials can be process- and frequency-dependent.     

Quasi-TEM modes in rectangular waveguides: a study based on the properties of PMC and hard surfaces

Hard surfaces or magnetic surfaces can be used to propagate quasi-TEM modes inside closed waveguides. The interesting feature of these modes is an almost uniform field distribution inside the waveguide. But the mechanisms governing how these surfaces act, how they can be characterized, and further how the modes propagate are not detailed in the literature. In this paper, we try to answer these questions. We give some basic rules that govern the propagation of the quasi-TEM modes, and show that many of their characteristics (i.e. their dispersion curves) can be deduced from the simple analysis of the reflection properties of the involved surfaces.     

Single-mode rib optical waveguides on SOG/SU-8 polymer and integrated Mach-Zehnder for designing thermal sensors

This paper presents a successful design, realization,and characterization of single-mode rib optical waveguides on SOG/SU-8 polymers in order to highlight a new approach to designing heat sensors. The basic principle of this new thermal-sensing method relies on the differential thermal behavior regarding both acting arms of a micro Mach-Zehnder Interferometer(MZI). First, two families of single-mode straight rib waveguides composed of SOG/SU-8 polymers are analyzed. Hence, optical losses for TE/sub 00/ and TM/sub 00/ optical modes for structures on Si/SiO/sub 2//SU-8 have been estimated respectively as 1,36 /spl plusmn/ 0,02 and 2,01/spl plusmn/0,02 dB/spl middot/cm/sup -1/, while the second one composed of Si/SiO/sub 2//SOG/SU-8 presented losses of 2,33 /spl plusmn/ 0,02 and 2,95/spl plusmn/0,02 dB/spl middot/cm/sup -1/. Then, owing to modeling results, an experimental sensor is realized as an integrated device made up of SU-8 polymer mounted on a standard silicon wafer. When subjected to a radiant source, as a laser light (980 nm) is injected across the cleaved input face of the MZI, the significant change of output signal allows us to consider a new approach to measuring radiant heat flowrate. Experimental results are given regarding the obtained phase shift against the subjected thermal power. According to the modeling results, one can expect new highly sensitive devices to be developed in the next coming years, with advantageous prospective industrial applications.     

Reflectenna: a quasi passive on?off keyed microwave telemetry system for remote sensor applications

A method to transmit one-directional wireless data with low power consumption has been investigated. This system, called the 'reflectenna', works on the principle of transmitting information by modulating an incident continuous wave carrier signal prior to re-transmission and consists of two orthogonally linear polarised, micromachined microstrip patch antennas and a single-pole-single-throw switch that modulates the carrier signal. This quasi-passive method to transmit data has been tested with a transceiver system that transmits a 10 GHz carrier signal and demodulates the received signal reflected back from the reflectenna. The carrier signal was modulated with a 2 kHz square wave and a link with a range up to 25 m was achieved.     

Group delay equalised monolithic microwave integrated circuit amplifier for ultra-wideband based on right/left-handed transmission line design approach

A group delay equalised InGaP/GaAs HBT monolithic microwave integrated circuit (MMIC) amplifier with an active balun for ultra-wideband (UWB) application has been developed. The MMIC consists of a broadband amplifier with an active balun and a group delay equaliser. The group delay equaliser was designed based on a theory using a composite right/left-handed (CRLH) transmission line. Adding a right-handed (RH) transmission line to a CRLH transmission line in parallel, a convex group delay characteristic is realised. Since various UWB components have concave group delay characteristics, the group delay equaliser can compensate a concave group delay characteristic of the amplifier in an operation frequency band. In this paper, dispersion, group delay and impedance characteristics for the proposed CRLH/RH circuit have been theoretically analysed. Moreover, a minimised group delay equaliser circuit on an MMIC has been designed and fabricated based on the proposed CRLH/RH circuit. A fabricated group delay equalised InGaP/GaAs HBT MMIC amplifier with an active balun exhibited an improved group delay characteristic compared with the MMIC amplifier without the group delay equaliser. The standard deviations of group delays for a frequency variation in a gain band were decreased from 12.8 to 5.5 ps at S₂₁ and decreased from 10.3 to 7.3 ps at S₃₁.     

Realization of integrated polarizer and color filters based on subwavelength metallic gratings using a hybrid numerical scheme

This study realizes integrated polarizer and RGB (red, green, and blue) color filters using single- and multiple-layered subwavelength metallic grating structures. A hybrid numerical scheme based on the rigorous coupled-wave analysis method and a genetic algorithm is used to determine the optimal values of the grating period, filling factor, and grating thickness of three different grating structures, namely, a single-layer grating, a double-layer grating, and a double-layer grating with a lateral shift. The optical performance of the various structures is evaluated and compared in terms of the transmission efficiency at the center wavelengths 700.0?nm, 546.1?nm, and 435.8?nm of red, green, and blue light, respectively, and the extinction ratio over the visible wavelength spectrum (380-780?nm). It is shown that the double-layer grating achieves a transmission efficiency of about 50% and an extinction ratio of around 60?dB. Thus, this grating structure provides a convenient and effective means of achieving the polarizing and filtering functions in LCD panels using a single device.     

A comprehensive study on the planar type of goubau line for millimetre and submillimetre wave integrated circuits

Modifications of the traditional Goubau line into its planar type for implementation to integrated circuits of millimetre and submillimetre waves are studied in frequency range 100-400 GHz. Features and performances of this new type of transmission lines are studied for different line configurations, different dimensions and new materials with low dielectric constants. To improve the performance of this type of transmission line, perforated dielectrics or new dielectrics are used to reduce the permittivity of the supporting and adjacent slabs. Selections of line parameters are demonstrated and compared. Both miniature hybrid microwave integrated circuit and microwave integrated circuit compatible configurations are studied and discussed. Some results of characteristic impedance of this type of lines are also reported     

Retrieval of vertical constituents and temperature profiles from passive submillimeter wave limb observations of the Martian atmosphere: a feasibility study

The investigation of the Martian atmosphere is of key importance for an understanding of the planets present and past. Passive limb observations of thermal radiation at submillimeter wavelengths in the 320-350-GHz range by use of a state-of-the-art satellite receiver on a low Mars orbit allow important parameters such as the mixing ratios of H2O, HDO, 12CO, 13CO, O3, and H2O2 as well as the thermal profile to be retrieved with high precision and unprecedented vertical range and resolution, providing valuable information for better understanding of the planet's water cycle, atmospheric dynamics, and photochemistry. The feasibility of these kinds of measurement is demonstrated by means of model simulations based on realistic atmospheric, spectroscopic, and instrumental parameters. Temperature can be retrieved to approximately 90 km with half-scale height vertical resolution from single-scan measurements of emission lines of the long-lived species 12CO and 13CO. The global water-vapor distribution can be measured even under dry or wet conditions with good vertical resolution from the surface to approximately 45 km, and simultaneous observations of HDO allow useful information on the D/H ratio up to an altitude of approximately 30 km to be derived. The sensitivity of the limb-sounding technique also permits information on the photochemically important minor species O3, and H2O2 to be obtained. It is shown that spectral averaging may improve precision, altitude range, and resolution of the retrieved profiles. Other frequency bands are explored, and the 435-465-GHz range is suggested as a possible alternative to the 320-350-GHz range.     

A photonic circuit for complementary frequency shifting,in-phase quadrature/single sideband modulation and frequency multiplication: analysis and integration feasibility

A novel photonic integrated circuit architecture for implementing orthogonal frequency division multiplexing by means of photonic generation of phase-correlated sub-carriers is proposed. The circuit can also be used for implementing complex modulation, frequency up-conversion of the electrical signal to the optical domain and frequency multiplication. The principles of operation of the circuit are expounded using transmission matrices and the predictions of the analysis are verified by computer simulation using an industry-standard software tool. Non-ideal scenarios that may affect the correct function of the circuit are taken into consideration and quantified. The discussion of integration feasibility is illustrated by a photonic integrated circuit that has been fabricated using ‘library’ components and which features most of the elements of the proposed circuit architecture. The circuit is found to be practical and may be fabricated in any material platform that offers a linear electro-optic modulator such as organic or ferroelectric thin films hybridized with silicon photonics.     

A theoretical study on a novel solar based integrated system for simultaneous production of cooling and heating

An integrated system for simultaneous production of triple-effect cooling and single stage heating is proposed in this paper to harness low grade solar energy. The proposed system combines the heliostat field with a central receiver and the ejector-absorption cycle with the shaft power driven transcritical CO₂ cycle. A parametric study based on first and second laws of thermodynamics is carried out to ascertain the effect of varying the exit temperature of duratherm oil, turbine inlet pressure, and evaporators temperature on the energy and exergy output as well as on the energy and exergy efficiencies of the system. The results obtained indicate that major source of exergy destruction is the central receiver where 52.5% of the inlet solar heat exergy is lost followed by the heliostat where 25% of the inlet exergy is destroyed. The energy and exergy efficiencies of the integrated system vary from 32% to 39% and 2.5%–4.0%, respectively, with a rise in the hot oil outlet temperature from 160 °C–180 °C. It is further shown that increase in evaporator temperature of transcritical CO₂ cycle from −20 °C to 0 °C increases the energy efficiency from 27.45% to 43.27% and exergy efficiency from 2.51% to 2.97%, respectively. The results clearly show how the variation in the values of hot oil outlet temperature, turbine inlet pressure, and the evaporator temperature of transcritical CO2 cycle strongly influences the attainable performance of the integrated system.     

A novel proposal for all-optical compact and fast XOR/XNOR gate based on photonic crystal

In this paper, we aim to design an all-optical device, which can perform XOR and XNOR functions in a single structure. The proposed structure will be realized by cascading two nonlinear resonant rings. The functionality of the proposed structure is based on controlling the optical behaviour of optical rings via optical intensity. The final structure has one bias and two input control ports, along with two output ports. One port acts as an XOR and the other acts as an XNOR gate. The maximum delay times for the XOR and XNOR gates are 1.5 and 2.5?ps, respectively. Therefore, the working bit rates for the XOR and XNOR gates are 666 and 400?Gbit/s, respectively.     

In situ oil/water separation using hydrophobic-oleophilic fibrous wall: a lab-scale feasibility study for groundwater cleanup

Kapok, a natural plant fiber, possesses excellent hydrophobic-oleophilic characteristics. Its innovative use as hydrophobic-oleophilic wall that allows permeation of oil but not water into an oil recovery well is proposed. Its performance was investigated through laboratory experiments, in which diesel was used as the experimental oil. A two-dimensional hydraulic flume was setup to physically model the oil/water separation by the kapok wall. The influences of packing density, kapok wall thickness and oil thickness on the oil recovery rate were examined. The oil permeability of the packed kapok decreased from 0.0165 cm2 at 34 g/L packing density to 0.0038 cm2 at 70 g/L packing density. The kapok wall exhibited complete rejection of water while allowed oil to permeate through. The excellent oil/water separation by the kapok wall was due to surface interaction between the kapok fibers and the oil, which resulted in spontaneous penetration and permeation of the oil through the kapok wall. The oil recovery rate increased with thickness of the oil layer in the feed stream. When the oil thickness exceeded 60 mm, a constant flux of 3.8-5.0, 3.2-3.3 and 2.5-2.7 L/(m2 min) could be achieved by the kapok wall of 55-, 75- and 95-mm thick, respectively, under the natural pressure gradient. The kapok wall could be reused for several wetting/drying cycles, and only lost 27% of its initial oil permeability.     

Meta-heuristic based decision support for portfolio optimization with a case study on tracking error minimization in passive portfolio management

In this paper we describe the concept and design of a meta-heuristic based decision support system generator (DSS-generator) for portfolio optimization. We report extensively on experience with the application of a specific DSS that has been customized for controlling and optimizing passively managed stock funds. Here, the constraints from the law on investment trust companies as well as several fund specific guidelines prohibit that the benchmark can be identically reproduced. For measuring the performance of the portfolio a tracking error model with data stemming from a factor model is applied. Our results show that the system provides proposals for the fund manager in acceptable time which are feasible with respect to the guidelines and excellent in quality.     

新型SiO_2基微/介孔材料的合成及其对集成电路生产中VOCs废气的吸附研究

采用新型SiO2基微/介孔材料为吸附剂,针对集成电路(Integrated Ciruit,IC)产业中废气排放的特点,以丙酮、苯、甲苯为挥发性有机化合物(VOCs)的典型,进行了一系列吸附实验.用气相色谱定时测取VOCs获得动态穿透曲线,就各VOCs分别在SiO2基微/介孔材料、疏水沸石、活性炭3种吸附荆上的吸附以及SiO2基微/介孔材料对3种不同VOCs的吸附进行了研究,同时考察了水蒸汽脱附对该材料吸附性能的影响.实验结果显示,该吸附剂在对VOCs的吸附中较疏水沸石FX-I和活性炭有着明显的优势,主要表现在透过时间的延迟和传质区长度的缩短.     

An integrated scheduling and material-handling approach for complex job shops: a computational study

We suggest an extension of the shifting bottleneck heuristic for complex job shops that takes the operations of automated material-handling systems (AMHS) into account. The heuristic is used within a rolling horizon approach. The job-shop environment contains parallel batching machines, machines with sequence-dependent setup times, and re-entrant process flows. Jobs are transported by an AMHS. Semiconductor wafer fabrication facilities (wafer fabs) are typical examples for manufacturing systems with these characteristics. Our primary performance measure is total weighted tardiness (TWT). The shifting bottleneck heuristic (SBH) uses a disjunctive graph to decompose the overall scheduling problem into scheduling problems for single machine groups and for transport operations. The scheduling algorithms for these scheduling problems are called subproblem solution procedures (SSPs). We consider SSPs based on dispatching rules. In this paper, we are also interested in how much we can gain in terms of TWT if we apply more sophisticated SSPs for scheduling the transport operations. We suggest a Variable Neighbourhood Search (VNS) based SSP for this situation. We conduct simulation experiments in a dynamic job-shop environment in order to assess the performance of the suggested algorithms. The integrated SBH outperforms common dispatching rules in many situations. Using near to optimal SSPs leads to improved results compared with dispatching based SSPs for the transport operations.     

Theoretical and experimental study on passive mode-locking composite Nd:GdVO4/Nd:GdVO4/Nd:GdVO4 lasers

Stable passive mode-locking multi-segment composite Nd:GdVO₄ lasers with a semiconductor saturable absorber mirror were demonstrated for the first time. For the composite crystals, the output power increased linearly with the increase of the incident pump power, showing excellent thermo-mechanical performances. While for the conventional crystal, power saturation was observed when the incident pump power exceeded 8.79 W. The maximum average output power of 1.465 W was achieved by Nd(0.1%):GdVO₄/Nd(0.5%):GdVO₄/Nd(1%):GdVO₄ composite crystal at an incident pump power of 9.28 W. The largest pulse energy of 14.90 nJ and the highest peak power of 0.53 kW with a pulse duration of 28.0 ps were also obtained by using the same composite crystal, revealing that the multi-segment composite crystal with a proper combination of Nd³⁺-doped concentrations could obtain the optimal laser performance.