Composite Cavity Research Articles

Impact of U-shaped waveguide structures on optical comb generation in microresonator systems

In the research of soliton microcombs, the pump energy conversion efficiency (ECE) of the microcomb is an important parameter. However, in traditional microresonator systems, the ECE is only a few percent. Researchers have enhanced it by introducing additional feedback coupling structures or composite cavity structures into the microresonator system to suppress the output of pump light in the soliton generation region. The additional structures may affect the output comb characteristics of the system, but most articles do not delve into this issue, which hinders the practical application of high-efficiency soliton microcombs. In this paper, we establish rate equations describing the nonlinear dynamics of a microresonator with a U-shaped waveguide feedback coupling structure (coupled-cavity system, CCS), and numerically simulate and conduct steady-state analysis of the simulation results to obtain the influence of the U-shaped waveguide on the CCS’s output comb characteristics. Then we optimize the structural parameters of the CCS reducing the parametric oscillation threshold of the pump by more than 50%, while increasing the ECE to over 25% when the optical field in the microresonator propagates in the form of a single soliton.

Utilizing an aspheric lens and compound ellipsoidal cavity for a laser uniform illumination system

To achieve uniform laser illumination of an active imaging system with a small aperture diameter and large field angle, we have developed what we believe to be a novel structure for achieving uniform beam shaping that integrates a laser source, an aspheric lens, and a composite ellipsoidal cavity to enable active laser illumination. Through an aspheric lens, the fundamental mode Gaussian beam is transformed into double Gaussian and flat-top radiation at the target plane. The double Gaussian radiation is further reflected by a complex ellipsoidal cavity, where it is evenly distributed into equal radiation flux. This flux combines with the flat-top radiation, resulting in a uniform distribution at the target plane. The parameters of the complex ellipsoidal cavity are determined using an equalization algorithm. After combining the transmission for flat-top shaping by the aspheric lens and secondary reflection shaping by the composite ellipsoidal cavity, we achieved an aperture measuring 29.7 mm with an aperture angle of 84.0°, at a distance of 2 m from the target plane, with a diameter of 3.6 m, resulting in uniformity reaching 92.7%. RMS and MT/R determine the effectiveness of the compound ellipsoidal cavity design, depending on the maximum reflection angle and transmission angle. MT/R is inversely proportional to the maximum reflection angle, while RMS is directly proportional to the transmission angle. By setting the maximum reflection angle to 32.0° and the transmission angle to 8.0°, we were able to achieve a minimum root-mean-square focusing radius of 108.6 µm along with a minimum effective MT/R ratio of 1.07. The overlap degree between transmission and reflection directly impacts the target plane’s uniformity, adjusted through a defined adjustment factor. Optimizing this factor to 0.9 maximizes the uniformity of the target plane.

Vibroacoustic Analysis of Laminated Composite L-shaped Acoustic Cavity using Multi-domain Coupled BE-FE Method

Vibroacoustic Analysis of Laminated Composite L-shaped Acoustic Cavity using Multi-domain Coupled BE-FE Method

Chimeric versus Multiple Flaps for Composite Oral Cavity Defects: A Systematic Review and Meta-Analysis.

Complex head and neck defects involving composite defects can be reconstructed using chimeric flaps or multiple flaps with separate anastomoses. Limited comparisons exist between chimeric and multiple flap reconstructions. We compare outcomes between chimeric and multiple flap reconstructions in oral cavity reconstruction. PubMed (NLM), Embase (Elsevier), Web of Science (Clarivate Analytics), and Cochrane CENTRAL (Wiley). A systematic review was conducted, including English articles reporting outcomes of oral cavity reconstruction with either chimeric flaps or multiple flaps. Data extraction included patient characteristics, flap type, and outcomes such as flap survival, partial flap loss, operating room time, hospital length of stay, and postoperative complications. Forty-seven articles comprising 1435 patients were included. Notably, 552 patients underwent multiple flaps, while 883 received chimeric flaps. Meta-analysis revealed no statistically significant difference in flap survival between chimeric and multiple flap patients (98% vs. 99%, p = 0.198). Multiple flap patients had higher rates of operating room take-backs for anastomotic issues and longer hospital stays compared with chimeric flap patients. There were no significant differences in partial flap failure, resumption of diet and speech, need for subsequent flaps, fistula formation, or general complications. This large-scale meta-analysis demonstrates equivalent flap survival between chimeric and multiple flaps in the reconstruction of composite oral cavity defects. Both approaches appear to be safe and acceptable, with comparable outcomes in terms of diet and speech resumption, rates of fistulization, and general postoperative complications. Multiple flap patients had higher rates of operating room take-backs and longer hospital stays. NA Laryngoscope, 134:4196-4202, 2024.

Nd:YVO4/YVO4 cascaded Raman laser pumped dual-wavelength signal wave MgO:PPLN-OPO with wide range adjustable wavelength interval

This article presents a dual-wavelength signal wave output system capable of generating a broad range of adjustable wavelength intervals. The setup involved the creation of a dual-wavelength cascaded Raman laser featuring composite cavities operating at 1176 nm and 1313 nm. Experimental investigations were carried out on an external cavity MgO:PPLN-OPO driven by the cascaded Raman laser. By setting the crystal polarization period to 27.6-34.4 µm and the temperature to 50-130°C, adjustable tunable output of dual-wavelength signal wave at 1176 nm-MgO:PPLN-OPO (1550-2294 nm) and 1313 nm-MgO:PPLN-OPO (1768-2189 nm) was achieved with a wavelength interval of 0-218 nm. Under the conditions of a period of 34.4 µm, temperature of 90°C, and an incident Raman power of 2.6 W, the highest conversion efficiency of Raman to dual-wavelength signal wave (2212, 2182 nm) was 34.2%. Furthermore, the maximum output power of dual-wavelength signal wave was recorded at 1.02 W with an incident Raman power of 3.33 W.

Characteristics of natural convection heat transfer in composite cavity

In order to study the influence of the nature of the mining airspace on the natural convection heat transfer in the unventilated working face, we establish a numerical model of natural convection in a composite cavity containing porous media by CFD method. The effects of different Rayleigh numbers (Ra), porous media thicknesses, and porosities ε on the natural convection temperature and velocity fields and heat dissipation from the heat source were comparatively analyzed. The results show that the larger Ra is, the stronger the natural convection flow and heat transfer in the composite cavity; when the thickness of porous media increases from 0.2 to 0.75, the average Nussel number (Nuave) of the high-temperature wall surface decreases by 40.38%, the Nuave of the interfaces decreases by 6.15%, the maximum dimensionless velocity of the boundary layer in the porous region decreases from 10,771 to 3775, and the dimensionless horizontal line in the center of cavity decreases by 0.05, indicating that the natural convection temperature and velocity fields and heat dissipation from the heat source are affected by different Ra. Temperature decreased by 0.05, demonstrating that the increase in the thickness of porous media will weaken the strength of the fluid side of the flow and heat transfer; porosity increased from 0.2 to 0.8, and the interfacial Nuave increased by 5.61%, demonstrating that the larger porosity makes the porous media area flow and heat transfer enhancement, but has a certain weakening effect on the flow and heat transfer in the fluid domain. The results of the study can be used for the natural convection flow and heat transfer in the unventilated coal mining face, and provide some reference value for avoiding the thermal damage of mechanical equipment.

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.

Brightness enhancement on a narrow-linewidth fiber Bragg grating-based master oscillator power amplification fiber laser

Abstract In this paper, we have experimentally demonstrated a high-power and high-brightness narrow-linewidth fiber amplifier seeded by an optimized fiber oscillator. In order to improve the temporal stability, the fiber oscillator consists of a composite fiber Bragg grating-based cavity with an external feedback structure. By optimizing the forward and backward pumping ratio, the nonlinear effects and stimulated Raman scattering-induced mode distortion of the fiber amplifier are suppressed comprehensively, accompanied with the simultaneous improvement of beam quality and output power. The laser brightness is enhanced further by raising the threshold of transverse mode instability by approximately 1.0 kW by coiling the gain fiber with a novel curvature shape. Finally, a 6 kW narrow-linewidth laser is achieved with beam quality (M2) of approximately 1.4. The laser brightness doubled compared to the results before optimization. To the best of our knowledge, it is the highest brightness narrow-linewidth fiber laser based on a one-stage master oscillator power amplification structure.

Microwave Characterization of Glucose Level Using Composite PMS-HMSIW Cavity Resonator Integrated With Microfluidic Channel

Microwave Characterization of Glucose Level Using Composite PMS-HMSIW Cavity Resonator Integrated With Microfluidic Channel

Digital laser with composite resonator for optiocal vortex laser generation

We propose a composite cavity configuration that resonates a digital laser and seeds it to the master resonator for power boost which shows the potential for power scaling of digital laser system.

Hybrid multi-channel electrically tunable bandstop filter based on DAST electro-optical material

A voltage tunable hybrid multi-channel bandstop filter based on a metal–insulator–metal (MIM) waveguide is presented in this work, which can realize three narrowband and one broadband filtering functions simultaneously. The filter comprises two asymmetric composite cavities, which are filled with organic electro-optical material of 4-dimethylamino-N-methyl-4-toluenesulfonate (DAST). The composite cavity is composed of a rectangular cavity and an annular cavity, and the annular cavity is formed by two rectangular cavities connected with two semi-elliptical annular cavities. The transmission spectrum and magnetic field distribution of the filter are studied and analyzed by the finite element method (FEM), and the effects of the structure parameters on the transmission spectrum are discussed. Our analysis indicates that the bandstop filter has minimum transmittances of 0.02%, 0.29%, and 0.1%, minimum bandwidths of 5 nm, 9 nm, and 25 nm, and maximum quality factors (Q) of 123.7, 87.1, and 44.2, respectively, in three narrowband modes. The stopband bandwidth at the broadband mode is 70 nm, and the adjustable range is 1695–2065 nm. Additionally, the filter characteristics can be adjusted by imposing a control voltage, providing a high degree of tunability and maintaining stable filter performance. Finally, the basic structure is optimized yielding an increased bandwidth of 238 nm for the broadband mode, which does retain great electrical tuning characteristics. Consequently, the proposed structure can be applied with huge potential in high-density integrated circuits and nano-optics.

Bipaddle Pectoralis Major Myocutaneous Flap (PMMC) for Complex Composite Oral Cavity Defects: An Experience of a Tertiary Cancer Centre.

Although microvascular free flaps are considered the first choice in head and neck cancer defect reconstruction, their use is limited in developing regions by availability of resources and the expertise .The Bipaddle pectoralis major myocutaneous flap (PMMC flap) is a commonly used flap in head and neck cancer reconstruction, but in literature flap is associated with high incidence of drawbacks including donor site morbidity and added bulk of the flap reducing cosmetics and function. The purpose of the study is to evaluate the Bipaddle PMMC flap reliability, operative technique and outcome in reconstructive head and neck cancer surgery in the era of microvascular free flaps. Its a prospective study in which the records of 50 patients treated with Bippadle PMMC flap reconstruction between January 2022 to July 2022 were systematically collected and reviewed. Data of recipient site, serum albumin, history of adjuvant, recurrence, defect dimension, type of donor site closure, length of hospital stay, postoperative complications and outcomes were analysed. There were 45 males and 5 females with a mean age of 41 years (31-60). Bipaddle PMMC flap reconstruction was done in all patients of advanced squamous cell carcinoma of oral cavity. There were two males with complete necrosis of flap salvaged with latissimus dorsi flap and forehead flap. Minor infections were noted in two female and one male patient, managed conservatively and recovered well with acceptable final outcome. The Bipaddle PMMC flap is reliable for large defects in head and neck reconstructive surgery, particularly when a bulky flap is required to reconstruct composite defects where the lesion is involving the skin. Placing the flap horizontally with inclusion of nipple and areola in most of the patients increased the reach and size of available flap.

Passive white light cavities with metal coatings.

White light cavities with broadband resonance are usually filled with negative dispersion medium, which inevitably leads to gain. In this article, pure passive white light cavities are designed, in which negative dispersion medium is no longer necessary. Theoretically, if the reflection phase of the cavity wall can exhibit a negative dispersion slope, then it can also satisfy white light cavities conditions without medium. In practice, the negative dispersion property of the cavity wall can be realized by two metal coatings with different reflection coefficients. Therefore, our white light cavities are composite cavities, in which the main cavity provides resonance while the auxiliary cavity forms the cavity wall, providing negative dispersion reflection phase. Further, atomic gas can be employed to improve the performance of the white light cavities. Atomic gas exploits effects such as Electromagnetic Induced Transparency (EIT), enabling the white light cavities to be controlled by coherent driving field. With the passive characters, our design can be realized and implemented much more easily.

Optical fiber temperature sensor based on beat frequency and Vernier effect of fiber ring resonator composite cavity

A fiber temperature sensing scheme based on beat frequency and Vernier effect of fiber ring resonator (FRR) with composite cavity is proposed and experimentally demonstrated. The optical FRR as a sensor is put into the linear cavity fiber laser, and Vernier effect is generated when the resonance spectrum of the optical FRR and the longitudinal mode of the laser are superimposed. The beat frequency envelope spectrum corresponding to the longitudinal mode Vernier spectrum is used to realize fiber ring sensing in electrical domain, and the sensing information is obtained by tracing the envelope of beat frequency signal, which has the advantages of stable system, simple structure, low cost and high sensitivity.

Clinical Justification for Preliminary Thermal Exposure to Composite in the Treatment of Caries: Randomized Clinical Trial

Background. Polymer composites have good aesthetic characteristics and pronounced physicochemical properties, as compared to traditional restorative materials such as amalgam. However, the polymerization reaction of composite material containing bismethacrylate group commonly used in clinical practice is always accompanied by a different degree of volumetric shrinkage (2.7%~7.1%). The resulting stress can lead to adhesion failure and some other unfavorable clinical consequences, such as enamel destruction, microcracking of composite material and formation of microleakage between composite and tooth cavity wall, which can result in recurrent caries and postoperative sensitivity, thereby affecting the long-term effect of restoration. Therefore, studying the effect of preheating on composite restoration is important for its clinical application. Objective. To improve the effectiveness of treatment of patients with dental caries by improving the physicochemical properties of composite restorations.Methods. A randomized clinical trial enrolled 180 patients aged 18 to 45 years, diagnosed with dentin caries class I, according to Black (K02.1 in ICD). The study was conducted in the Dental Clinic of Kuban State Medical University, Russia. 180 composite restorations were performed in the treatment of dentin caries of molars. Patients were randomized into 2 groups): the control group — 90 patients and the main group — 90 patients. The control and main groups, in turn, were divided into three subgroups, depending on the composite used — Estelite Sigma Quick (Tokuyama Dental, Japan), Filtek Bulk Fill Posterior Restorative (3M Espe, USA) and DentLight (VladMiVa, Russia). Each subgroup consisted of 30 patients. In the control group, the classical method of filling with a composite material at “room temperature” was applied. In the main group, a composite heating conditioner “Ena Heat” (Micerium, Italy) was used to heat the composite to 55 °C before adapting the material in the formed cavity with subsequent photopolymerization. The quality of composite restorations within the clinical study was evaluated using the modified Ryge criterion immediately after treatment and after 6, 12, 18, 24 months. Statistical processing of the obtained data was carried out by means of one-factor analysis of variance using the GraphPadPrism 9 program (GraphPad Software, USA).Results. The duration of the clinical study comprised 24 months. The study revealed a statistically significant decrease in the quality of marginal fit of composite restorations (according to the Ryge score) by 20.1% (p = 0.0001) in the control group and by 5.7% (p = 0.0328) in the main group. At the same time, no statistically significant changes in Ryge scores were reported in the subgroups of composite materials of the main group (pF = 0.9480, pE = 0.1837, pD = 0.2529). As a result of the study, an optimal time algorithm (7 seconds) for using a special furnace for preheating the composite before sealing with subsequent photopolymerization was obtained.Conclusion. The study revealed a statistically significant positive effect of the proposed algorithm for working with a heated composite on the quality of marginal fit in the long term after treatment in comparison with the classical method of working with a composite at “room temperature”.

P‐173: Late‐News Poster: Composite Cavity Design for Long Lifetime and Low Cost Organic Light‐Emitting Diodes Displays

Traditional way to upgrade the stability and current efficiency performance of OLED device is seeking for new generation of electroluminescent materials. We provide a composite cavity design for longer lifetime, lower cost, and equivalent luminance by using the same materials. It consists of two first‐order red and green cavities and a second‐order blue cavity, which means different optical thickness of the RGB micro cavities. Due to the shorter distance between emitting molecules and metal electrodes, 1st order cavity obtains longer lifetime by surface plasmon coupling. A 52.7% improvement of calculated white lifetime can be accomplished with a respective 89.1% and 54.9% longer lifetime of red and green devices. 1/3 even more organic materials can be saved. Less angular luminance decay and lower working voltage are also demonstrated in the experimental part.

A Quad-Band Shared-Aperture Antenna Based on Dual-Mode Composite Quarter-Mode SIW Cavity for 5G and 6G with MIMO Capability

This study introduces a new design for an ultra-compact shared-aperture antenna utilizing a quarter-mode substrate integrated waveguide (QMSIW) cavity. The proposed antenna operates as a 4 × 4 multi-input multi-output (MIMO) system in three 5G/6G millimeter-wave (MMw) bands, while functioning as a single element antenna for a 5.5 GHz wireless fidelity Microwave (Mw) band. The antenna comprises four QMSIW cavity resonators; each QMSIW is loaded with dual slots to produce tri-band MMw operation at 28 GHz, 38 GHz, and 0.13 THz. The four cavities are arranged to reuse the entire aperture by creating a conventional open-loop antenna that operates at a frequency of 5.5 GHz. Simulation, measurement, and co-simulation results show that the proposed antenna has a quad-band operation and exhibits favorable characteristics. The measured scattering parameters validate the simulated ones over the four bands under consideration. The lowest values of the measured total radiation efficiencies are 80%, 73%, 62%, and 72% (co-simulation) within the four covered bands, respectively. The antenna peak gains are 1.8 to 1.85 dBi, 4.0 to 4.5 dBi, 4.3 to 4.5 dBi, and 6.5 to 6.6 dBi within the covered bands. Furthermore, the design satisfies MIMO and diversity conditions (envelope correlation coefficient and branch power ratio) over frequency bands of operation. All excellent results are achieved from an ultra-compact size in terms of footprint area (0.018λ02), where λ0 represents the free space wavelength at 5.5 GHz. The antenna boasts an excellent reuse aperture utilization efficiency (RAU) of 92% and a large ratio frequency of 23, making it an ideal candidate for compact devices. With its superior performance, the proposed design is well-suited for a range ofs wireless communication systems, including mobile devices and the Internet of Things.

Single Longitudinal Mode Parity-Time Symmetric Brillouin Fiber Laser Based on Lithium Niobate Phase Modulator Sagnac Loop

A single longitudinal mode (SLM) parity-time (PT) symmetric Brillouin fiber laser (BFL) based on z-cut lithium niobate phase modulator (LN-PM) Sagnac loop with Hz level linewidth is proposed and experimentally verified. A 10 km single-mode fiber provide SBS gain, while an LN-PM Sagnac loop consisting of an LN-PM and two polarization controllers (PCs) is used to achieve PT symmetry. Two mutually linked feedback loops supporting orthogonally polarized light are created by utilizing inherent birefringence of LN waveguide from LN-PM without electrical signal modulation. One of the feedback loops experiences gain in a clockwise direction and the other loss in a counterclockwise direction. The polarization state of the stokes injected into the LN-PM is controlled by adjusting the PC, and SLM BFL can be achieved when the gain and loss are well matched and exceed the coupling coefficient to break the PT symmetry. Compared with existing BFL studies, this design does not call for frequency matching of several composite cavity structures or precise control of ultra-narrow bandwidth bandpass filters. In addition, a frequency-locking system based on Pound-Drever-Hall technology is employed to lessen the instability and external disturbances brought on by the ring cavity. In the experiment, the linewidth of PT symmetry BFL based on LN-PM Sagnac loop is 3.85 Hz, according to the measured linewidth of 77 Hz at the −20 dB power point. A 65 dB optical signal-to-noise ratio and a 43 dB maximum side mode suppression ratio are measured. Furthermore, the PT symmetry BFL's wavelength is tuned between 1550 and 1550.41 nm.

Design of solar concentrated uniform linear light source of composite ellipsoid cavity

The predecessor of China Optics was China Optics and Applied Optics Digest, which was founded in 1985. At that time, it was the only retrieval journal in the field of optics in China. At the end of 2008, China Optics and Applied Optics Digest was renamed

A Composite Cavity for Mode Control in Broad-Area Diode Laser

A unstable cavity structure composed of the arc-shaped cavity, Fabry-Perot cavity, and sidewall saw-tooth microstructure is proposed to achieve mode selection in high-power broad-area diode laser with 980nm wavelength. In this cavity, the loss difference between the higher-order modes and the fundamental mode is increased to suppress the lasing of higher-order modes. The lateral divergence is reduced by about 28%. The number of modes in the near-field spot is reduced and the light intensity is concentrated towards the center of the Near-field profile. Also, the lateral beam parameter product decreases by 15%.