Horizontal Slot Research Articles

Nanophotonic waveguide based on engineered horizontal-vertical slots for polarization independent bio-chemical sensing

A nanophotonic waveguide based on engineered horizontal and vertical slots is proposed. The proposed engineered structure is composed of three silicon ribs forming two vertical slots, and on top a gold cover in the shape of microchannel forms horizontal slot regions. We are able to increase the bulk sensitivity in TM mode by 1.5 times with the gold cover. The bulk sensitivity for TE and TM mode is reported to be 1.024 n m − 1 and 0.95 n m − 1 , respectively. Surface sensitivity, investigated numerically, is 0.265 × 10 − 2 R I U / n m for DNA hybridization and 2.3 × 2 π / r a d for hepatitis surface antigen detection.

Experimental study on the removal of fine particles using hole-slotted collectors in wet electrostatic precipitators

ABSTRACT The fine particles are considered a significant environmental pollution problem. The wet electrostatic precipitators (ESPs) are now used most widely among the advanced fine particle removal technologies. The rigid glass fiber reinforced plastics (FRP) collectors modified with hole-slotted structures were used to enhance the water film distribution over their surfaces. This paper experimentally investigated the effects of the hole-slot patterns and the operating parameters on the particle removal performance in wet ESPs using the hole-slot-structured collector. The voltage-current characteristics and the energy consumption among the different pattern collectors were discussed. Besides, the effects of the water film on the particle number concentration classification and the effects of the applied voltage and the specific collecting electrode areas (SCA) on the relative collection efficiency (RCE) were investigated and discussed. The experiment results show that the corona current of three hole-slot structured FRP collectors was higher than that of the conventional rigid collectors (CRC) at the same voltage. Using the FRP collectors with circular holes and horizontal slots could decrease the energy consumption and using the FRP collectors with vertical slots increases the energy consumption compared with the CRC when the collection efficiency was lower than 92.5%. The water film could increase the collection efficiency of the fine particles and prevent the fine particles cross through the holes and the slots. The hole-slot-structured FRP collectors were appropriate for the working conditions of high SCA and long residence time. When the water film in the hole and slotted structures was incomplete, the fine particles could pass through the collector plate to form secondary back-mixing. Implications: The wet ESPs are used most widely among the advanced treatment technologies of the fine particles’ removal. The rigid glass fiber reinforced plastics (FRP) collectors modified with hole-slotted structures were used to enhance the water film distribution over their surfaces. The hole-slot-structured FRP collectors were appropriate for the working conditions of high SCA and long residence time. When the water film in the hole and slotted structures was incomplete, the fine particles could pass through the collector plate to form secondary back-mixing.

Modelling viscous fluid filtration to select optimal bottom-hole filter designs

Determining the resistance value of filters with a filtering surface of mesh and block type is difficult mathematically. This is because many parameters affecting the shell filtration capacity. As for the mesh filters, depending on the type of weaving, the different thickness of weft and warp, the different size in the horizontal and vertical planes, the frame structure which is integral with the mesh have critical influence. As for block constructions, it is the size and uniformity of the composition of the particles, the thickness of the filter shell, the geometry of the filtration channels and other features that play the role. It is, therefore, more convenient for such filters to assess their permeability. The most promising filters are the frames with horizontal slots which have considerably less resistance and interference of the holes. In addition, the features of the frame-rod filter device make it easy to realize a greater inlet area than in other designs, with the same minimum size of the slots. Recommendations for choosing the inlet areas and the size of the filter slots should consider factors related to well production rate, the formation fluid viscosity, particle size distribution of the formations, granulometric composition of the formation, consolidation factor of the bottom-hole zone, clodding and bridging of the deposits.

Theoretical investigation of compact high-resolution interleaved arrayed waveguide gratings with multi-layer structures

In this paper, a compact high-resolution two-stage interleaved arrayed waveguide grating (AWG) system with a 3D structure on a silicon nitride (Si3N4) platform is proposed. The device is comprised of a 7-channel primary AWG with a 0.4-nm resolution and seven 26-channel second-stage AWGs, each with a 2.8-nm resolution. Different arrayed waveguide widths are utilized to achieve the wavelength tuning of the second-stage AWGs. The AWGs have a greater fabrication tolerance than conventional AWGs. A taper-MMI input structure is utilized to make the -3 dB pass-band reach 0.4 nm, which is 100% of the channel spacing. Also, the horizontal slot arrayed waveguides are individually introduced into the AWG to reduce the inter-layer crossing and bending losses, which is also found to greatly reduce the footprint of the device. The proposed AWGs have an average crosstalk of about -24 dB in the 2-µm band, demonstrating the feasibility of the on-chip 3D optoelectronic integration design.

Sensor of high frequency electric fields intensity on the base of slot waveguides with electro-optic polymer filling

Purpose. Development of the structure and operation principles of high frequency electric fields intensity optical sensor.
 Methods. Method of lines was used for calculation of propagation constants and mode electric fields distribution of strip waveguides with vertical and horizontal slots filled with electro-optical polymer SEO125.
 Findings. The structure and operation principles of high frequency electric fields intensity sensor on the base of slot waveguides with vertical and horizontal slots filled with electro-optical polymer are proposed. Sensor makes it possible measuring the variable electric fields with frequencies up to 10 MHz. The sensor sensitivity order is of 30 V/m.
 Application field of research. Determination of fire-dangerous and injurious factors of electric field during emergencies elimination.

Study on Analysis and Fabrication Conditions of Horizontal SiO<sub>2</sub> Slot Waveguides Using Nb<sub>2</sub>O<sub>5</sub>

Horizontal slot waveguides enable light to be strongly confined in thin regions. The strong confinement of light in the slot region offers the advantages of enhancing the interaction of light with matter and providing highly sensitive sensing devices. We theoretically investigated fundamental characteristics of horizontal slot waveguides using Nb2O5. The coupling coefficient between SiO2 slot and air slot waveguides was calculated. Characteristics of bending loss in slot waveguide were also analyzed. The etching conditions in reactive ion etching needed to obtain a sidewall with high verticality were studied. We propose a process for fabricating horizontal slot waveguides using Nb2O5 thin film deposition and selective etching of SiO2. Horizontal slot waveguides were fabricated that had an SiO2 slot of less than 30 nm SiO2. The propagated light passing through the slot waveguides was also obtained.

Compact and broadband silicon-based transverse electric-pass power splitter using triple-guide directional couplers with hybrid plasmonic waveguides and subwavelength gratings

A compact and broadband transverse electric (TE)-pass power splitter using triple-guide directional couplers (TGDCs) is proposed and analyzed in detail, where the TGDCs are formed by two outside subwavelength grating (SWG) waveguides and a central strip waveguide with segmented hybrid plasmonic waveguides (HPWs) on its top. For input transverse magnetic (TM) mode, it is transmitted along the central strip waveguide, gradually transferred from the strip waveguide into the horizontal slots formed by strip waveguide and HPWs, and finally radiated into the claddings since the HPWs are segmented. As to the TE mode, by choosing suitable structural parameters, phase-matching condition is only satisfied for TE mode so that it is evenly coupled from the central waveguide into the outside SWG waveguides, effectively preventing the coupling of the residual TM mode in the TGDC. Consequently, a TE-pass power splitter is realized. Moreover, efficient transitions between the SWG and strip waveguides are used at the end of the outside SWG waveguides. Results show that, with the number of the segments of the HPWs being 6, a compact device of ∼9 μm in length is achieved with an insertion loss (IL) of 0.56 dB (TE), an extinction ratio (ER) of 23.74 dB, and a reflection loss of −30.6 dB (−4.94 dB) for TE (TM) mode at 1.55 μm. Also, the bandwidth is up to 150 nm when ER > 15 dB and IL < 0.9 dB. In addition, fabrication tolerances to the key structural parameters are investigated and field evolution through the present device is also presented.

Circular polarization reconfigurable antenna for mid-band 5G applications with a new reconfigurable technique

In this paper, a novel low cost, single-feed, and circular polarization reconfigurable antenna is designed and fabricated for future mid-band 5G applications. An innovative technique is used in this approach, which combines three techniques, namely: polygon U-slot, switchable vertical or horizontal slots, and shorting posts. The proposed antenna can alter its polarization sense between RHCP and LHCP with the ability to adjust the axial ratio position with respect to frequency along the impedance bandwidth of the antenna. The antenna is built on RT/duroid 5880 substrate with a maximum size of (31*31*3.15) .Two real diodes are integrated across the slot to change polarization sense. CST commercial software is used to simulate the antenna, and then it is fabricated and measured practically. Good agreements between the two results are achieved. However, The antenna has impedance bandwidth starting from 3.4995GHz to 3.73GHz with overlapped axial ratio bandwidth of 2.1% for both operation senses. Also, the antenna has good gain, and it has one resonant frequency at 3.6GHz for both operating states.

Sulfuric acid speleogenesis in the North Caucasus: Sharo-Argun valley Caves (Chechen Republic, Russia)

Geological and hydrogeological conditions in the North Caucasian monocline allow ascending cross-formational flow and discharge of artesian waters from Upper Jurassic and Lower Cretaceous strata, thus enabling hypogene karst. The presence of evaporites (gypsum and anhydrite) in the deep-seated Mesozoic deposits promotes the sulfate-reduction processes, which supply H2S in the waters, thus enabling the sulfuric acid speleogenesis (SAS). Here we report on four hypogene caves of the Sharo-Argun valley. Three caves, Sheki, Magomed, and Kamila are presently active; H2S waters discharge through them. The fourth cave, Said-Emin is in the fossilized state. The active caves are characterized by high H2S contents in the air (up to 60 ppmv), high acidity of condensation solutions (pH 0.5–3.0) and abundant bacterial biofilms and mats dominated by sulfur-oxidizing bacteria. Morphological features of the caves (feeders, condensation-corrosion domes, horizontal water table notches and slots, gypsum replacement pockets, etc.) and mineral deposits (replacement gypsum, native sulfur, minerals of the alunite group) are typical of the cases formed by SAS. Sulfates and native sulfur of the caves have ‘light’ δ34S isotope compositions, consistent with sulfate-reduction in deep seated conditions and subsequent H2S oxidation in the near-surface conditions.

Theoretical study of microcavity-enhanced absorption spectroscopy for mid-infrared methane detection using a chalcogenide/silica-on-fluoride horizontal slot-waveguide racetrack resonator.

The reported chalcogenide (ChG) rectangular waveguide sensors with a small evanescent field need a large waveguide length to obtain an enhanced light-gas interaction effect. To make such sensors compact and improve the light-gas interaction effect, a microcavity-enhanced absorption spectroscopy technique for methane (CH4) detection was proposed using a mid-infrared chalcogenide/silica-on-fluoride horizontal slot-waveguide racetrack resonator. For the horizontal slot waveguide, an equivalent sensor model (ESM) and related formulations were proposed to simplify the analysis of the racetrack resonator sensor model (RRSM), and the ESM was verified through a comparison between the theoretical result of ESM and the simulation result of RRSM based on the finite element method (FEM). Due to the use of a chalcogenide/silica-on-fluoride horizontal slot-waveguide structure, the waveguide parameters were optimized to obtain a high power confinement factor of 44.63% at the wavelength of 3291 nm, which is at least 5 times higher than other ChG rectangular waveguides. The waveguide length is reduced at least 30 times due to the use of the optimized chalcogenide/silica-on-fluoride horizontal slot-waveguide and racetrack resonator. The limit of detection (LoD) is 3.87 ppm with an intrinsic waveguide loss of 3 dB/cm and an amplitude coupling ratio of 0.1 for the resonator. The response time is less than 5 µs due to the small light-gas interaction area. The influences of environmental pressure and waveguide intrinsic loss on the sensing characteristics were discussed. The compact racetrack resonator sensor structure and equivalent analytical model can also be adopted in the design of an on-chip waveguide sensor for the detection of other gas species.

An NFC-CPT-Combined Coupler With Series- None Compensation for Metal-Cover Smartphone Applications

A near-field communication capacitive power transfer (NFC-CPT)-combined coupler with a series-none compensation topology is proposed for metal-cover smartphone applications. To achieve capacitive power transfer through metal cover, the metal cover itself is used as the receiving metal plates. To realize NFC through metal cover, the cross slot including a slim horizontal slot and a rectangular slot is embedded on the metal cover, which mitigates the eddy current loss and increases the inductive coupling for the NFC antenna. Besides, the cross slot divides the metal cover into two separate metal plates, which is necessary for capacitive power transfer. Considering the space limitation and safety requirement, no compensation components are integrated inside the smartphone and only a series inductance is integrated on the transmitter side. A prototype of the proposed NFC-CPT-combined coupler has been built. The wireless power transfer and NFC through metal cover have been validated through experiment. The experimental results show that the prototype achieves 5-W output power with a 93.5% circuit efficiency at 6.78 MHz, and the detection range of the NFC antenna is 61 mm.

Uniform microwave heating system design and evaluation with an orthogonally slot‐loaded array waveguide

AbstractIn this article, we propose a 1‐kW 2.45 GHz microwave applicator with an orthogonally slot‐loaded array waveguide to improve the heating uniformity. In the conventional microwave applicator with rectangular waveguides, the heating uniformity is low due to various hot and cold spots. Using the proposed slot‐loaded array waveguide having horizontal and vertical slots, the proposed microwave applicator realizes a uniform temperature variation in the heating material and achieves an improved uniformity of up to 77.4% at 2.45 GHz compared to the conventional microwave applicator.

Radiation beam scanning for leaky wave antenna by using slots

This paper provides an insight of a new, microstrip leaky wave antenna. It holds the ability to continue steer its beam at a swapping frequency. This is done with acceptable impedance matching while scanning and very little gain variation. Investigation is carried out on LWAs’ control radiation pattern in steps at a band frequency via vertical and horizontal slots. The enhancement is realized by etching horizontal and vertical slots on the radiation element. This study also presents a novel half-width microstrip leaky wave antenna (LWA). The antenna is made up of the following basic structures group’s vertical and horizontal slots. The reactance profile at the microstrip’s free edge and thus the main beam direction is changed once the control-cell states are changed. The radiation pattern direction changes by sweeping the operating frequency between 4 GHz to 6 GHz.The main beam may be directed by the antenna between 15 o and 55 o . C band achieved the measured peak gain of the antenna of 10 dBi at 4.3 GHz beam scanning range.

Strip-loaded horizontal slot waveguide for routing microdisk laser emission

A strip-loaded horizontal slot waveguide is used for routing the emission of a microdisk laser. The active region of the laser contains InAs/InGaAs/GaAs quantum dots operating in CW mode under optical pumping. Although the quantum dots emit in a broad range, the laser emission is single mode with λ = 1290 nm . Atomic layer deposition is used for the fabrication of the TiO 2 / SiO 2 / TiO 2 slot waveguide covering the 10-µm-diameter disk. The horizontal slot waveguide covers the microdisk and traps the emission in the fundamental TM mode of the three-stack layer. Once light is localized inside this planar waveguide, a loading strip creates an effective index difference, which is sufficient to confine the mode laterally and leads to the guiding of the lasing emission. An analytical model for the five-layer horizontal planar slot waveguide was developed in order to optimize the slot waveguide according to the operation wavelength of the microlaser and the different materials involved. Scanning near-field optical microscopy is used to observe the propagation of light within the waveguide and confirm the mode coupling into it and therefore the guiding along the loading strip.

Epitaxial single-crystal rare-earth oxide in horizontal slot waveguide for silicon-based integrated active photonic devices.

We have epitaxially grown high-quality single-crystal rare-earth oxide thin films, including Gd2O3 and erbium-incorporated (ErGd)2O3, on silicon-on-insulator substrate, and investigated their optical properties when embedded in horizontal slot waveguides. (ErGd)2O3 with an erbium concentration in the mid-1021 cm-3 range shows well-resolved Stark-split photoluminescence emission peaks in the telecommunications band and a photoluminescence lifetime-concentration product as large as 2.67×1018 s·cm-3 at room-temperature. Using these materials, horizontal slot waveguides with strong optical confinement in low-refractive-index rare-earth oxide layers, have been fabricated for silicon-based integrated active photonic devices. Thanks to the strong light-matter interaction, a large waveguide modal absorption of 88 dB/cm related to erbium ions is achieved, leading to a large potential optical gain. Intense emissions from the waveguides are also observed, with a radiation efficiency on the order of 10-4. These results indicate that a combination of epitaxial rare-earth oxide thin films and horizontal slot waveguides provides a promising platform for light amplification and generation on silicon.

Three-Octave Supercontinuum Generation Using SiO2 Cladded Si3N4 Slot Waveguide With All-Normal Dispersion

We investigate a silicon nitride (Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> ) horizontal slot waveguide with silicon dioxide (SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) cladding, which can achieve a flat and low normal dispersion of -15.56 ps/(nm·km) over a 3270-nm wavelength range from 1170 to 4440 nm, covering a 1.9 octave bandwidth. By launching a 100-fs 90-kW hyperbolic secant input pump pulse, a three-octave supercontinuum (SC) from 504 to 4229 nm can be generated using a 5-mm long waveguide. The generated SC spectrum is highly coherent, as it is mainly expanded by self-phase modulation (SPM) and optical wave breaking (OWB) in all-normal dispersion regime. The degree of coherence can achieve >0.99 from 1250 to 4300 nm. Therefore, the proposed waveguide could potentially serve as a key element in the on-chip broadband source for silicon photonic platform.

Characteristics and Performance of Microstrip Patch antenna for C Band and X Band

This article present a compact proposed patch antenna for impedance matched for simple two horizontal slot is placed in a active patch with a via hole in sandwiched between radiated patch and bottom plane of an microstrip patch antenna for a band of 4 to 12Ghz application. The planned antenna is synthesized by using glass reinforced epoxy laminated material (FR4) and electromagnetic 3D view (IE3D) software. The software based design is suitable for a band of 3.3//5.5 Wi-Max and 5.3/5.8 WLAN frequency band. It is also suitable for satellite application The ground and exciting patch is separated by 1.5mm thickness. The proposed antenna parameter is design for 10Ghz..For such design the achieved Bandwidth for an antenna is 53 % at a VSWR&lt;2, acceptable return loss (S11) = - 22.5dB, and the directivity of an antenna is 6 dBi. The antenna is appropriate for an application of X band. The designs of an antenna and its result have been discussed in detail.

A compact broadband coplanar waveguide fed circularly polarized printed monopole antenna with asymmetric modified ground plane

In this communication, a broadband circularly polarized (CP) monopole antenna with coplanar waveguide (CPW) feeding is proposed. It consists of a modified rectangular monopole, an asymmetric ground plane, a two-linked inverted L-shaped strips on the left CPW ground, and two rectangular horizontal slots in asymmetric CPW ground plane. The overall dimension is only 0.47λ o × 0.47λ o. The antenna prototype has been fabricated. The measured results indicate that a broad −10 dB impedance bandwidth (IBW) of 107.5% (4.3 GHz, 1.85-6.15 GHz) and a broad 3 dB axial ratio ARBW of 104.3% (4 GHz, 1.855-5.9 GHz) can be achieved; the average realized gain is 2.3 dBi for the entire CP band. The proposed antenna is an attractive candidate for several wireless communication systems.

Compact cross-slot waveguide polarization beam splitter using a sandwich-type coupler.

A compact silicon-based cross-slot waveguide (CSW) polarization beam splitter (PBS) utilizing a sandwich-type coupler is proposed. The coupler consists of two identical CSWs separated by a horizontal slot waveguide (HSW), and S-bend sections at each end of the coupling section are introduced to decouple and separate the light. Owing to the strong birefringence of the HSW, the coupling length ratio between two different polarized modes (TE and TM) is adjustable in a suitable range by simply changing the gap width between the CSW and the HSW. The coupling length of the TM mode can be easily made half of that of the TE mode with a proper gap width, which is a favorable condition to realize a short PBS. Then, by making the length of the coupling section equal to the coupling length of the TE mode, the TE and TM modes are split. The PBS has the advantages of a small footprint and a high polarization extinction ratio (PER) and may be useful in the polarization management of a CSW-based on-chip optical system. Numerical results indicate that a PBS of ∼12µm with an insertion loss (IL) of 0.17 (0.53) dB, PER of 24.12 (21.14) dB for the TM (TE) mode is achieved at the wavelength of 1.55 µm, with a bandwidth covering the full C band for keeping PER>15dB and IL<1dB.

A Study to Assess the Bond Strength of Acrylic Teeth With Different Retentive Features.

ABSTRACTBackground and Aim:Flexible denture base has been gaining attention as a denture base material because of its toxicological safety, comfort, and enhanced aesthetics. Debonding of acrylic teeth from the flexible denture base material has posed a great problem to the clinician and patient. This study aimed at comparing the bond strength between flexible denture base with acrylic teeth having different mechanical modifications.Materials and Methods:Forty mandibular molar teeth (Combination Acry Rock, Badia Polesine (Ro), Italy) were used in four groups for mechanical modifications on the ridge lap area. The groups were group 1 (no mechanical modifications), group 2 (round groove 2 mm in diameter and 2 mm deep on the ridge lap surface), group 3 (horizontal slot 2 mm deep, 2 mm wide, and 4 mm long prepared on the ridge lap surface of the teeth), and group 4 (T-shaped groove 2 mm deep, 2 mm wide, and length of 4 mm mesiodistally and 2 mm buccolingually prepared with a straight fissure bur). The acrylic teeth were attached to a wax block of dimension 1.2 cm × 1.2 cm × 2.5 cm. These were flasked and dewaxed, followed by injection molding with Valplast flexible denture base material. The bond strength was assessed by attaching the specimens to universal testing machine tested under a tensile load at a cross-head speed of 1 mm/min till it fractured. Data obtained were statistically evaluated by one-way analysis of variance and post hoc test.Results:There was significant increase in mean bond strength after various mechanical modifications. Group with T-shaped diatoric hole showed greatest bond strength value compared to other groups.Conclusion:Incorporating mechanical retentive features with increased surface area and undercut can improve the bonding of acrylic teeth to flexible denture base.