Cavity Design Research Articles

Microarray Platforms Based on 3D Printing.

This paper introduces an innovative method for the fabrication and infusion of microwell arrays based on digital light processing (DLP) 3D printing. A low-cost DLP 3D printer is employed to fabricate microstructures rapidly with a broad dynamic range while maintaining high precision and fidelity. We constructed microwell arrays with varying diameters, from 200 to 2000 μm and multiple aspect ratios, in addition to microchannels with widths ranging from 45 to 1000 μm, proving the potential and flexibility of this fabrication method. The superimposition of parallel microchannels onto the microwell array, facilitated by positive or negative pressure, enabled the transfer of liquid to the microwells. Upon removal of the microchannel chip, a dispensed microdroplet array was obtained. This array can be modulated by adjusting the volume of the microwells and the inflow fluid. The filled microwell array allows chip-to-chip dispensing to the microreactor array through binding and centrifugation, facilitating multistep and multireagent assays. The 3D printing approach also enables the fabrication of intricate cavity designs, such as micropyramid arrays, which can be integrated with parallel microchannels to generate spheroid flowcells. This device demonstrated the ability to generate spheroids and manipulate their environment. We have successfully utilized precise modulation of spheroids size and performed parallel drug dose-response assays to evaluate its effectiveness. Furthermore, we managed to execute dynamic drug combinations based on a compact spheroids array, utilizing two orthogonal parallel microchannels. Our findings suggest that both the combination and temporal sequence of drug administration have a significant impact on therapeutic outcomes.

12-mJ 1-kHz cryogenically cooled rod Yb:YAG regenerative amplifier

We report on a continuous-wave (CW) pumped cryogenically cooled rod Yb:YAG regenerative amplifier delivering uncompressed 12-mJ, 90-ps, 1030-nm pulses at a 1-kHz repetition rate. The amplifier demonstrates an efficiency of 31.7%. A symmetric cavity design was utilized to compensate for the substantial thermal lensing effect, yielding a final measured beam quality of 1.1 in both horizontal and vertical directions. After significant gain narrowing, the measured spectra exhibit a bandwidth of 0.3 nm corresponding to an approximately 5 ps transform-limited pulse.

Analysis of the Marginal Continuity in Different Designs of Monolithic Zirconia Inlay-Retained Fixed Dental Prostheses: An In Vitro Study.

To evaluate the marginal integrity of three inlay-retained fixed dental prosthesis (IRFDP) designs fabricated using monolithic zirconia. In total, 30 IRFDPs were fabricated using 4-YTZP monolithic zirconia and randomly divided into three groups according to the cavity design. Groups ID2 and ID1.5 received an inlay cavity preparation, which includes a proximal box and an occlusal extension with a depth of 2 mm or 1.5 mm, respectively. Group PB received a proximal box cavity preparation without an occlusal extension. The restorations were fabricated and cemented using a dual-cure resin cement (Panavia V5) and subjected to an equivalent of 5 years of aging. The specimens were evaluated under an SEM to measure marginal continuity before and after the aging process. During the whole 5-year aging process, no specimens showed signs of cracking, fracture, or loss of retention in any restorations. In the SEM analysis, most marginal defects observed in the restorations were areas of microgaps at the tooth/cement interface (TC) or zirconia/cement interface (ZC), resulting in loss of adaptation. There was a significant difference between the groups after the aging process at both the TC (F = 4.762, P < .05) and ZC (F = 6.975, P < .05), with Group ID2 presenting the best performance. There was a significant difference between TC and ZC in all groups (P < .05), with ZC presenting more gaps in all groups. Inlay cavity designs including a proximal box and an occlusal extension exhibited better marginal stability than a proximal box without occlusal extension.

Hybrid Laser Cavity Design for Improved Photon Lifetime and Performance

Hybrid Laser Cavity Design for Improved Photon Lifetime and Performance

Synergistic Heat Transfer in Enclosures: A Hybrid Nanofluids Review

This review aims to comprehensively explore the concepts of heat transfer (HT) and entropy generation (Egen) within cavities containing hybrid nanofluids (HN). Additionally, the review encompasses various enclosure shapes, such as triangle, square, rectangle, wave, trapezoid, hexagon, octagon, semicircle, circle, cube, C-shaped, L-shaped, M-shaped, T-shaped, W-shaped, irregular shaped, and other types of cavity designs. Also, different types of hybrid nanoparticles such as silver-magnesium oxide, copper-aluminum oxide, multi-walled carbon nanotubes-iron oxide, copper-titanium dioxide, silver-copper, aluminum oxide-titanium dioxide, carbon nanotubes-aluminum oxide, multi-walled carbon nanotubes-magnesium oxide, carbon nanotubes-iron oxide, carbon nanotubes-copper, aluminum oxide-silicon dioxide, aluminum oxide-silver, nanodiamond-cobalt oxide, etc., and base fluids such as water, ethylene glycol, carboxymethyl cellulose, etc are presented in this research. In addition, a thorough analysis of the extensive literature underscores the significant influence of elements like blocks, obstacles, fins, or cylinders within cavities on both HT and Egen. These findings carry substantial practical implications for the study of thermofluid systems.

Low noise near-concentric optical cavity design.

Near-concentric cavities are excellent tools for enhancing an atom-light interaction as they combine a small mode volume with a large optical access for atom manipulation. However, they are sensitive to longitudinal and transverse misalignments. To address this sensitivity, we present a compact near-concentric optical cavity system with a residual cavity length variation δLC,rms = 0.36(2) Å. A key part of this system is a cage-like tensegrity mirror support structure that allows us to correct for longitudinal and transverse misalignments. The system is stable enough to allow the use of mirrors with a higher cavity finesse to enhance the atom-light coupling strength in cavity-QED applications.

Design Considerations for Continuous Wave Intracavity Backwards Optical Parametric Oscillators

In this paper, we report a theoretical systematic study of continuous wave intracavity backwards optical parametric oscillators based on periodically poled lithium niobate (PPLN) for mid-infrared (mid-IR) light generation. We study the effects of varying different cavity parameters including nonlinear crystal length, cavity size, pump laser diode spot size, output coupler radius, and cavity loss values on the output power and threshold of the proposed mid-IR laser. The effects of different physical phenomena are included in the model including pump depletion due to the nonlinear conversion process, the thermal lens effect, and mode overlap between the beams in the nonlinear crystal. We show that high output powers in the mid infrared (&gt;500 mW at 3.2 μm) can be achieved with proper cavity design and that a laser threshold with a PPLN as short as 2 cm can be reached.

Inorganic Material of Magnesium Nitrate Mg(NO3)2 Film as Q-Switcher in the C-Band Region

A novel inorganic material of Magnesium Nitrate (Mg(NO3)2) thin film is successfully investigated in the C-band region. The Q-switcher is Mg(NO3)2 thin film. The solvent casting method has been applied to prepare Mg(NO3)2 thin film before being positioned within the fiber ferrule duo to act as a Q-switcher. Thereby, the modulation depth and the saturation intensity of the Mg(NO3)2 thin film exhibit at 32.40% and 0.07 MW/cm2, respectively. It is possible to produce a steady Q-switched pulse fiber laser with a maximum pump power of 403.00 mW, a repetition rate of 72.56 kHz, and a pulse width of 3.00 µs. In addition, the tunable Q-switched pulse fiber laser is also examined using a figure-of-eight cavity design incorporating a tunable bandpass filter (TBF). Consequently, the operating wavelength is changed in the range of 1528 nm to 1552 nm, even while the pump power remains the same at 403.00 mW. During this time, the pulse width and repetition rate shifted from 2.10 µs to 4.10 µs and altered from 67.90 kHz to 35.80 kHz, respectively. Consequently, the Mg(NO3)2 thin film has the opportunity to be an effective saturable absorber for generating pulsed fiber lasers and can be applied in optical communications applications.

Scopes for Improvements in Energy Conservation and Thermomechanical Performance of Building Blocks in the Kingdom of Bahrain: A Literature Review

In regions with hot climates such as Bahrain, the utilization of air conditioning is indispensable in both public and private buildings to attain thermally comfortable indoor environments. External walls, constructed with building blocks, play a crucial role in the heat penetration into the building system. Despite extensive research on the cavity designs of building blocks, there has been a lack of comparison between individual block systems and integrated multi-block systems, considering both thermal and mechanical performance criteria simultaneously. Therefore, it is imperative to gather and review information on key parameters influencing the thermomechanical performance of building blocks, along with investigating techniques used to evaluate these parameters according to international standards. This review primarily focuses on these aspects. Additionally, it presents the historical evolution of housing types and the standard procedures followed by the Bahraini Government and block manufacturing companies in alignment with energy efficiency policies in Bahrain. Ultimately, this review aims to inspire researchers to explore other viable and innovative designs for enhancing the thermal insulation of building walls. By doing so, this work will contribute to Bahrain’s 2030 goals of fostering sustainability and mitigating environmental impact at a local level, while also aligning with the United Nations’ Sustainable Development Goals (SDGs) for 2030, specifically SDG 11, which aims to “make cities and human settlements sustainable”.

High-frequency microwave cavity design for high-mass dark matter axion searches

Abstract The haloscope based on the TM010 mode cavity is a well-established technique for detecting QCD axions. However, the method has limitations in detecting high-mass axion due to significant volume loss in the high-frequency cavity. Utilizing a higher-order mode cavity can effectively reduce the volume loss of the high-frequency cavity. The rotatable dielectric pieces as a tuning mechanism can compensate for the degradation of the form factor of the higher-order mode. Nevertheless, the introduction of dielectric causes additional volume loss. To address these issues, this paper proposes a novel design scheme by adding a central metal rod to the higher-order mode cavity tuned by dielectrics, which improves the performance of the haloscope due to the increased effective volume of the cavity detector. The superiority of the novel design is demonstrated by comparing its simulated performance with previous designs. Moreover, the feasibility of the scheme is verified by the full-wave simulation results of the mechanical design model.

OSNR enhancement of Rayleigh-assisted Brillouin-Raman fiber laser via double pass configuration.

We propose and demonstrate a 10 GHz spacing multi-wavelength Brillouin-Raman fiber laser (MBRFL) with wide bandwidth and an outstanding optical signal-to-noise ratio (OSNR). This is achieved by utilizing loop mirror at one end of the laser cavity through a symmetrical bi-directional Raman pumping scheme. The setup is arranged in a double pass configuration by employing different lengths of dispersion compensating fibers (DCF). The attainment of MBRFL with outstanding performance necessitates the optimization of Raman pump power, Brillouin pump wavelength, and DCF length. By employing an 11 km DCF, when setting the Brillouin pump wavelength at 1531.4 nm, 504 Stoke lines are produced with a channel spacing of 0.08 nm. All the counted laser lines have less than a 1-dB peak amplitude variation and are spread across a 40.4 nm bandwidth that covers from 1531.4 to 1571.8 nm wavelength. In this case, the Raman pump power is fixed at 900 mW which results in average OSNR and Stokes peak amplitude level of 28 dB and -7 dBm respectively. To date, this is the simplest cavity design with the widest bandwidth and flattest spectrum together with outstanding OSNR attained in 10 GHz spacing multi-wavelength fiber lasers that incorporate a single low-power Raman pump unit.

Design and fabrication of a coupled high-Q photonic nanocavity system with large coupling coefficients.

In a previous work, we demonstrated a coupled cavity system where photons in one storage cavity can be transferred to another storage cavity at an arbitrary time by applying a voltage pulse to a third cavity placed in a p-i-n junction. In this work, we demonstrate methods to improve the transfer efficiency and photon lifetimes of such a coupled system. Firstly, we designed a photonic-crystal structure that achieves a large coupling coefficient without reducing the radiation quality factor compared to the previously proposed structure: The photonic-crystal design was changed to a more symmetric configuration to suppress radiation losses and then optimized using an automatic structure tuning method based on the Covariance Matrix Adaptive Evolutional Strategy (CMAES). Here we added two improvements to achieve an evolution toward the desired direction in the two-dimensional target parameter space (spanned by the coupling coefficient and the inverse radiation loss). Secondly, to improve the experimental cavity quality factors, we developed a fabrication process that reduces the surface contamination associated with the fabrication of the p-i-n junction: We covered the photonic structure with a SiO2 mask to avoid the contamination and the electrode material was changed from Al to Au/Cr to enable cleaning by a weak acid. Owing to these improvements of the cavity design and the fabrication process, the obtained system provides coupling strengths that are about three times stronger and photon lifetimes that are about two times longer, compared to the previously reported system.

Thermalization rate of polaritons in strongly-coupled molecular systems

Abstract Polariton thermalization is a key process in achieving light–matter Bose–Einstein condensation, spanning from solid-state semiconductor microcavities at cryogenic temperatures to surface plasmon nanocavities with molecules at room temperature. Originated from the matter component of polariton states, the microscopic mechanisms of thermalization are closely tied to specific material properties. In this work, we investigate polariton thermalization in strongly-coupled molecular systems. We develop a microscopic theory addressing polariton thermalization through electron-phonon interactions (known as exciton-vibration coupling) with low-energy molecular vibrations. This theory presents a simple analytical method to calculate the temperature-dependent polariton thermalization rate, utilizing experimentally accessible spectral properties of bare molecules, such as the Stokes shift and temperature-dependent linewidth of photoluminescence, in conjunction with well-known parameters of optical cavities. Our findings demonstrate qualitative agreement with recent experimental reports of nonequilibrium polariton condensation in both ground and excited states, and explain the thermalization bottleneck effect observed at low temperatures. This study showcases the significance of vibrational degrees of freedom in polariton condensation and offers practical guidance for future experiments, including the selection of suitable material systems and cavity designs.

Enhancing Red Brick Performance: A Study on Aluminum Oxide/Graphite Composite Material Effects

The objective of this research was to add nano/micro composites to red bricks in order to reduce costs while increasing strength. A finite element model (FEM COMSOL) was created to determine the best cavity design and placement in nano/micro composite bricks in order to decrease density and boost mechanical characteristics. Several nano/micro composite materials were used to broaden this red brick’s mechanical, electrical, energy storage, and thermal uses. The development of a finite element model COMSOL for red brick blocks with the ideal cavity shape and location for analyzing mechanical characteristics was applied for the first time in the paper. The concrete blocks were produced and strengthened using two distinct types of nano/micro materials to further enhance the stretcher of red bricks’ nanocomposites. The addition of Al2O3/Graphite NPs influences the mechanical properties of clay bricks. A detached study of Al2O3/Graphite nanoparticles affects the mechanical properties of clay bricks including compressive strength, water absorption, and density is reported. It also includes the comparison of traditional clay bricks with Al2O3/Graphite NPs mixtures.

Influence of access cavity design on root canal instrumentation efficacy in molars - An in vitro study.

Several designs of access cavity have been evolved in the recent past with the concept of minimal tooth tissue removal which would improve the root canal treated teeth fracture resistance. To investigate the effect of conservative design access cavity during the instrumentation of maxillary molar root canals. Eighty noncarious maxillary molars were assigned to the traditional and conservative access groups (n = 40 each). After designated access preparations, the teeth were immersed in Lugols's solution for staining the pulp tissue. Root canal instrumentation was performed with TruNatomy file system. Pre- and postinstrumentation nano-computed tomography (CT) images were taken and reconstructed using CT-An software. Root canals volumetric analysis was done with CT-Vol software. The analysis of the data was dealt with Shapiro-Wilk test and independent t-test. The volume of pulp canal space before and after instrumentation changed significantly between the traditional and conservative access design groups, according to an independent t-test. In comparison, the mean volume of dentin removed was much larger in the TAC group (P = 0.0016). The independent t-test manifests difference significantly between traditional endodontic access cavity (TAC) and conservative access cavity (CAC) with percentage of unprepared canal walls. The mean percentage of unprepared area was significantly lesser in TAC group as compared to CAC group (P = 0.0022). The volume of dentin removed was greater in TAC than with the CAC design. The amount of untouched canal wall area was significantly higher in conservative access design than with the traditional access design group.

Optical injection locking and optical-fiber data transmission by directly modulated wavelength tunable laser transmitters

Enhancement of the small- and large-signal modulation performance of wavelength tunable laser diode (TLD) transmitters under strong optical injection locking (OIL) is investigated numerically in back-to-back and optical-fiber transmission schemes. Our model is based on the spatiotemporal description of laser dynamics as due to the composite cavity design of TLDs, the usual rate equation formalism is not directly applicable. We demonstrate that TLD transmission strongly depends on wavelength tuning, which was investigated over a 21-nm range between 1529 and 1550 nm emission wavelengths. The best performance for both free-running (FR) and OIL TLDs is achieved at shorter wavelengths, 1529 nm for our device. Although in both cases this is due to larger differential material gain at shorter wavelengths, the underlying physics of the effect is completely different. For an FR TLD, it is the resonance oscillation frequency (ROF) that defines the best modulation speed, while for an OIL TLD, the achievable modulation speed depends on the cavity mode shift due to optical injection. Both the ROF and the cavity mode shift increase when the differential gain increases. However, the ROF is the device’s fixed parameter, while the cavity mode shift is defined by the OIL conditions, and thus, it can be optimized. The superior performance of the optical fiber digital data transmission with the OIL TLD is demonstrated at around 20-Gb/s modulation speed for standard fibers. This result is attributed to an enhanced modulation response and suppressed frequency chirping of the OIL TLD, and it is important for practical utilization of TLD transmitters.

Deterministic placement and effective-mass pinning of topological polariton bound states in the continuum

The exciton-polaritons derived from the light-matter interaction of an optical bound state in the continuum (BIC) with the strong excitonic resonance in a transition metal dichalcogenide (TMD) monolayer can inherit ultra-long radiative lifetimes and significant nonlinearities up to room temperature. Yet such realization can be challenging with conventional approaches to the photonic cavity design, typically due to poorly-resolved Rabi splittings at room temperature and an unstable energy positioning of the BIC state. We show and experimentally validate a strategy to dramatically improve the state-of-the-art on both points, by embedding a tungsten disulfide (WS2) monolayer deep within a Bloch-surface-wave stack, where the photonic mode is moulded by a 1D photonic crystal with a compound periodicity. In particular, we introduce a deterministic placement principle to the design of the PhC, allowing to stabilize the energy positioning of a topologically-protected BIC polariton eigenstate, with an effective mass which we can robustly pre-assign at choice as either positive or negative. This is in stark contrast to typical waveguide realizations of polariton BICs: only negative polariton effective masses can be commonly achieved, while sudden jumps to a weaker-interacting positive-effective-mass BIC are at the same time possible upon small perturbations, in fact hijacking the advantage from a topological protection when present.

Composite Restoration Design Effect During Curing and Chewing.

The purpose of this work is to observe the effect of the cavity design of the direct composite restoration on a real case of the patient's tooth structures after applying his mandibular kinematics with finite element analysis. Four complex maxillomandibular models of teeth 17 and 47 were constructed from the patient's cone-beam acquisition and the patient's kinematic data recorded with Modjaw® were added. Different shapes and sizes of mesio-occluso-distal (M.O.D.) composite restorations were simulated, including the polymerization shrinkage of this material. Finite element analyses were used to observe the Von Mises stresses occurring during polymerization and mastication. The stresses were observed at the cavity margin and the amplitude of the stresses was higher when the enamel volume was lower. The reduction in occlusal enamel volume with the open-angle vestibular and palatal walls resulted in a greater increase in stresses observed on the structures. The occlusal enamel is the area that bears the maximum masticatory stress, the loss of this enamel volume generates a much greater concentration of stress on the underlying structures. It is important to preserve as much enamel tissue as possible when designing a cavity for a direct composite restoration.

Co-Influence of Restoration Bonding and Inlay Cavity Design on Fracture Load of Restored Tooth.

The aim of this study was to investigate the co-influence of indirect mesio- occlusal-distal (MOD) cavity geometry and inlay restoration bonding on quasi-static fracture load of the restored tooth. Forty-eight intact human molar teeth were selected and prepared for standardized edge-shaped or round-shaped MOD cavities. The resin composite (Cerasmart, GC) inlays were bonded with the state-of-the-art inlay bonding protocol or with intentionally deteriorated bonding using n-hexane-wax solution for preconditioning. Restored teeth were loaded along the long axis of the tooth. Ultimate fracture load was recorded, and the type of fracture was visually determined and classified. Statistical analysis of load values was performed by Kruskal-Wallis test. Round-shaped cavity design with bonded restoration presented the highest fracture load (1658N). Bonding had significant influence on the fracture load of roundshaped cavity design (p=0.0003), whereas cavity design had no influence when the bonding was deteriorated (p=0.8075). In the case of deteriorated bonding, either the inlay or tooth fractured separately whereas in the bonded inlays fractures were commonly found both in the tooth and inlay. According to this study, bonded inlay restoration increased fracture resistance, while cavity design had no statistical difference on fracture resistance of the restored tooth.

Evaluation of The Effect of Outer Skin Slope on Fire Safety in Double-Skin Façade Systems

In order to increase energy efficiency and user comfort, double skin façade designs are becoming increasingly popular in the built environment as an alternative to traditional façede and curtain walling systems. The vertical cavity between the outer and inner skins of double skin façade systems, which is critical for natural ventilation, can destroy the effectiveness of façade designs by creating fire hazards due to the creation of uninterrupted areas between spaces. It is essential for the sustainability of the buildings to make appropriate fire safety designs for the risks of spreading toxic gases released in a possible fire through the double skin façede cavity to monitor the design before the building is built and to take the necessary precautions. Therefore, that paper developed a numerical model using computational fluid dynamics to monitor the smoke propagation through the cavity of the double skin façade and the temperature changes in the building. As a contribution to the physical modeling studies of double skin façade systems in the literature, the effect of changing the slope of the outer skin on smoke propagation and temperature changes was investigated. A design model was created by developing 9 scenarios: 4 wide angles, 4 acute angles, and a right angle, each with an angle varying by 3 degrees. While acute-angle cavity designs increased the flue effect in the cavity and increased the direction speed and density of the smoke towards the cavity, wide-angle cavity designs reduced the ambient temperature.