Large Quality Factor Research Articles

Shaped pulses for transient compensation in quantum-limited electron spin resonance spectroscopy.

In high sensitivity inductive electron spin resonance spectroscopy, superconducting microwave resonators with large quality factors are employed. While they enhance the sensitivity, they also distort considerably the shape of the applied rectangular microwave control pulses, which limits the degree of control over the spin ensemble. Here, we employ shaped microwave pulses compensating the signal distortion to drive the spins faster than the resonator bandwidth. This translates into a shorter echo, with enhanced signal-to-noise ratio. The shaped pulses are also useful to minimize the dead-time of our spectrometer, which allows to reduce the wait time between successive drive pulses.

Low-Frequency Vibration Energy Harvesting With Bidomain LiNbO3 Single Crystals.

Low-frequency vibration energy harvesting is becoming increasingly important for environmentally friendly and biomedical applications in order to power various wearable and implanted devices. In this paper, we propose the use of piezoelectric congruent LiNbO3 (LN) single crystals, with an engineered bidomain structure, as an alternative to the widely employed lead-based PZT. We thus compared experimentally the pure vibration energy scavenging performance of square-shaped bidomain and single-domain Y+128°-cut LN crystals and a conventional bimorph soft PZT ceramic bonded to long spring-steel cantilevers as a function of the frequency, load resistance, and tip proof mass. At a low bending resonance frequency of ca. 32.2 Hz, the bidomain LN yielded an open-circuit voltage of 1.54 kV/g, almost one order of magnitude larger than that observed in PZT. The maximum extractable average power was found to be of 9.2 mW/g2 in the bidomain LN, 6.2 mW/g2 in the single-domain LN, and 1.8 mW/g2 in the PZT piezo-elastic cantilevers. With five times higher output power density of up to 11.0 mW/(cm [Formula: see text]) under resonance conditions, bidomain LN was thus shown to be a reliable lead-free and high-temperature alternative to PZT, thanks to its considerably larger quality factor and electromechanical conversion efficiency.

A Pb(Zr,Ti)O3–Pb(Zn1/3Nb2/3)O3–Bi(Mn2/3Sb1/3)O3 quaternary solid solution ceramic with low sintering temperature, high piezoelectric coefficient and large mechanical quality factor

A quaternary high-power piezoelectric ceramic of 0.9Pb(ZrxTi1−x)O3–0.06Pb(Zn1/3Nb2/3)O3–0.04Bi(Mn2/3Sb1/3)O3 + y mol% Fe2O3 (x = 0.45–0.53) was reported to exhibit excellent overall properties of $${{\varepsilon_{33}^{T} } \mathord{\left/ {\vphantom {{\varepsilon_{33}^{T} } {\varepsilon_{0} }}} \right. \kern-0pt} {\varepsilon_{0} }} = 1615$$ , d33 = 305 pC/N, kp = 0.56, Qm = 1678, and Tc = 302 °C at x = 0.48 and y = 0.7 as sintered at 1040 °C. The relevant mechanism was ascribed to the combined effect of the formation of a traditional morphotropic phase boundary, the low-temperature sintering and amphoteric role of Bi(Mn2/3Sb1/3)O3 and the modification of Fe2O3 doping. The results demonstrate that Bi-based complex perovskite Bi(Mn2/3Sb1/3)O3 can simultaneously provide soft and hard characteristics similar to traditional Pb(Mn1/3Sb2/3)O3 and Pb(Mn1/3Nb2/3)O3. The addition of a small amount of Fe3O3 was found to have an obvious effect on the densification behavior and grain growth, and to simultaneously promote the piezoelectric properties and quality factor Qm as y ˂ 0.9. Compared with traditional piezoelectric ceramics, low-sintering temperature and excellent piezoelectric properties indicate that the studied composition in current work could have potentials for low-cost high-power device applications.

Nonlinear Characteristics of Semiconductor Optical Amplifiers for Optical Switching Control Realization of Logic Gates

Abstract This paper studies the problem of data access at the receiver with large bit error rate and low quality factor. Due to this issue the information got inaccurately at the receiver side, the data should have high quality factor and low bit error rate to be simple of identification at the receiver when using the gates. The nonlinear properties of the semiconductor optical amplifier are utilized to accomplish the Boolean variable based math work, in which AND, NAND, and OR gates potentially used to endorse the Boolean function. Through blend this gates together any Boolean function can be accomplished and utilized to perform optical signal processing. The quality factor and BER are measured by utilizing the eye diagram analyzer, the state of the output bit and also shaped by the oscilloscope visualizer in optiwave simulation program. These models can be used for wavelength converter, header recognition, parity checking, binary addition, packet-header modification, encoding and encryption with pattern matching, and data encryption with high speed and high quality factor.

Sensitive label-free sensor with high figure of merit based on plasmonic metasurface with unit cell of double two-split nanorings

We theoretically propose a sensitive label-free sensor with high figure of merit (FoM) based on Fano resonances on a plasmonic metasurface whose unit cell consists of double two-split nanorings by finite-element method. The unit cell of the proposed Fano resonant structure comprises of two thin gold nanorings each with two splits. Two Fano modes are generated in near-infrared regime through symmetry breaking by rotating the splits in nanorings in opposite directions. The fundamental feature of the proposed sensor is its relatively simple structure, double-mode usable, a large single-side quality factor of 566, and high FoM value of 378. According to our knowledge, these values are higher than those previously reported. The sensor has high substance resolving capability that its minimum detectable refractive index change can be as small as 0.00236, making it possible to distinguish different bio-tissues.

High Temperature Stability and Mechanical Quality Factor of Donor-Acceptor Co-Doped BaTiO <sub>3</sub> Piezoelectrics

Low temperature stability has limited the applications at elevated temperature for ABO3-type lead-free ceramics. And multi-grade resonances of piezoelectric ceramics are hardly obtained although the resonances are very important in some applications such as filter and resonator. High piezoelectric properties and large mechanical quality factors with multi-grade resonances can be obtained in (Li+-La3+) co-doped BaTiO3 ceramics, and excellent temperature stabilities are achieved in the ceramics. It has been shown that the thermal treatments both with and without electric field at 200 ℃ improve the piezoelectric properties and thermal stability further. Large piezoelectric constant (272 pC N-1) and huge mechanical quality factor (2012) was obtained after thermal-electrical treatment, which is caused by Li+-La3+ ionic pair aligning along the external electric filed during thermal-electrical treatment. Moreover, the present study provides an effective method to design combination properties with high temperature stability for ABO3 perovskite ferroelectric ceramics.

Thermal loading effects on Nd:YAG solar-laser performance in end-pumping and side-pumping configurations: a review

Solar-pumped solid-state lasers are promising for many applications. Among the potential applications of solar lasers are Earth, ocean, and atmospheric sensing; laser beaming; deep space communications; and energy support in space. A solar laser has also a large potential for many terrestrial applications, e.g., high temperature materials processing, magnesium–hydrogen energy cycle and so on. Solar-pumped lasers are natural candidates for applications where sunlight is plentiful and other forms of energy sources are scarce. As solar energy is the main continuous energy source in space, this technology becomes particularly attractive for space-based applications. Compared with electrically powered lasers, solar-pumped lasers benefit from simplicity and reliability because of the complete elimination of the electrical power generation and conditioning equipment. Since the report of the first sun-pumped solid-state laser, several pumping schemes have been proposed for enhancing solar-laser performance. Although the most efficient solar-laser systems have end-pumping approaches, the thermal loading effects caused by nonuniform distribution of absorbed pump light in these pumping configurations negatively affect their efficiencies. The side-pumping configuration can present higher laser beam quality as it allows uniform absorption distribution along the laser rod axis and spreads the absorbed power within the laser medium, reducing the associated thermal loading problems. Here, we report a review of research carried out on Nd:YAG solar-lasers with continuous wave emission, using either end-pumping or side-pumping techniques with a special focus on the thermal loading effects on the solar-lasers performance. In the end-pumping configuration, record-high multimode collection efficiency of 32.1 W / m2 is attained by pumping a 6-mm diameter, 95-mm length, Nd:YAG/YAG rod with 1.03 m2 area Fresnel lens. However, large beam quality factors of (Mx2=My2=61) have been associated with this approach, resulting in poor beam quality. In fundamental-mode operating, TEM00-mode, with this pumping technique, the highest collection efficiency is 7.9 W / m2 by pumping a 4-mm diameter, 35-mm length, Nd:YAG rod with 1.18-m2 area parabolic mirror with the lowest beam quality factors of 1.2. In the side-pumping configuration, the multimode collection efficiency was quite low; in contrast, the beam quality factors are much reduced. Low beam quality factors of (Mx2=8.9) and My2=9.6) are obtained by pumping a 4-mm diameter, 30-mm length, Nd:YAG rod with 2.88-m2 area parabolic mirror with only 9.6 W / m2 multimode collection efficiency. The highest multi-mode collection efficiency achieved with this pumping method is 11.7 W / m2 by pumping a 7-mm diameter, 30-mm length, Cr:Nd:YAG rod with 2.88-m2 area parabolic mirror. In the TEM00-mode regime, using the side-pumping method, the maximum collection efficiency is 4.0 W / m2 by pumping a 4-mm diameter, 25-mm length, Nd:YAG rod with 1.13-m2 area parabolic mirror. Beam quality factors <1.05 are reached by pumping a thin and long Nd:YAG rod (3-mm diameter and 50-mm length), with 1.18-m2 area parabolic mirror. More importantly, a TEM00-mode solar-laser with 1.7% laser power stability is produced, being significantly more stable than the previous TEM00-mode solar-lasers.

Design of a 3D Wilkinson power divider using through glass via technology * * Projected supported by the National Natural Science Foundation of China (Nos. 61771268, 61571248, U1709218), the Science and Technology Fund of Zhejiang Province (No. 2015C31090), the Natural Science Foundation of Zhejiang (No. LY17F040002), and the K. C. Wong Magna Fund in Ningbo University.

Due to its low electrical loss and low process cost, a glass interposer has been developed to provide a compelling alternative to the silicon-based interposer for packaging of future 2-D and 3-D ICs. In this study, through glass vias (TGVs) are used to implement 3-D inductors for minimal footprint and large quality factor. Using the inductors and parallel plate capacitors, a compact 3-D Wilkinson power divider is designed and analyzed. Compared with some reported power dividers, the proposed TGV-based circuit has an ultra-compact size and excellent electrical performance.

Acousto-Optical Transducer With Optomechanical Gain

The acousto-optical response of a microtoroidal optomechanical microresonator with optically compensated damping factor is measured and analyzed. We demonstrate that the large optical quality factor combined with the enhanced acoustic response due to radiation pressure make optomechanical microresonators excellent candidates as sensitive acousto-optical transducers with extremely low power consumption.

Simultaneous Large Mode Index and High Quality Factor in Infrared Hyperbolic Metamaterials

Semiconductor hyperbolic metamaterials comprise alternating doped (metal) and undoped (dielectric) subwavelength semiconductor layers. These materials support high wavevector modes called volume plasmon polaritons. Here, we investigate the quality and modal indices of volume plasmon polaritons in three semiconductor systems: Si:InGaAs/InAlAs, Si:InAs/GaSb, and Si:InAs/AlSb. We are able to demonstrate modal indices as high as 15, which is higher than any other artificial hyperbolic metamaterial within its respective wavelength range. We achieve this while maintaining quality factors as high as 14, comparable to those same material systems. Understanding of how the material combinations of these semiconductor hyperbolic metamaterials affect the volume plasmon polaritons provides the groundwork for the development of tunable, low-loss, infrared optoelectronic devices.

High-efficiency filters for photonic integrated networks: a brief analysis

In this paper, wide band pass filters (BPFs) and narrow band stop filters (BSFs) based on photonic crystals with large tunability have been achieved by using the resonance effect of crystal rings. The crystal structure (pillars) situated over the substrate of air is silicon, with permittivity contrast of 1/11.7 and a 2D lattice of the hexagonal system with appropriate permittivity contrast value of 1/8.9. The proposed structure is designed for the waveguide width 0.2 µm and wafer dimension 20 µm × 20 µm. The diamond ring square pillar filter possesses the highest quality factor (QF) of 1066.429 for 1493 nm drop signal with a narrow bandwidth of 1 nm. The hexagonal ring circular pillar filter acquires the highest QF of 134.5133 among the designed BPFs. The wider bandwidth of 100.4 nm is achieved by the diamond ring elliptical pillar BPF in the range of 1800–1900 nm. A bi-periodic circular pillar BSF is obtained with the large QF of 702.2727 and with the narrow bandwidth of 1.8 nm. Both the BPFs and the BSFs work at the second and third windows of an optical system, making the filters suitable for wavelength division multiplexing and networking applications.

Mid-infrared emissions of Dy3+ doped Ga-As-S chalcogenide glasses and fibers and their potential for a 42 μm fiber laser

For developing an ideal efficient and low-threshold medium for fiber lasers operated at 4 μm wavebands, 0.05 wt.% to 0.5 wt.% Dy3+ ions doped Ga0.8As39.2S60 chalcogenide glasses were investigated and a 4.2 μm fiber laser was theoretically studied based on the rate and propagation equations. It was shown that the Ga0.8As39.2S60 glass shows a desirable large Dy3+ ion solubility, which has been increased by an order of magnitude compared to As2S3 glass. Dy-rich nanocrystallines were found when the Dy3+ ions’ concentration is more than 0.3wt.% (i.e. 3000 ppmw), and the concentration quenching was found based on spectral analysis; however, no rapid decreases in lifetimes were observed. 0.3wt.% Dy3+ doped Ga0.8As39.2S60 glass possesses relatively large laser quality factor σemi × τmea = 1.70 × 10−23 cm2·s and excellent thermal stability (ΔT = 182°C), which can be successfully drawn into fibers indicating good potential for mid-infrared fiber laser.

Spectroscopic properties of Dy3+ doped tellurite glass with Ag/TiO2 nanoparticles inclusion: Judd−Ofelt analysis

Silver (Ag) and Titania (TiO2) nanoparticles (ATNPs) co−embedded and dysprosium (Dy3+) ions doped magnesium−zinc−tellurite glasses were synthesized via melt quenching method. As−prepared samples were characterized using various analytical tools. Nanoparticles concentration dependent spectroscopic properties of the prepared glasses were evaluated using Judd−Ofelt (J−O) analysis. XRD pattern verified the amorphous nature of as−quenched samples. The UV–Vis spectra revealed six absorption bands centred at 1690, 1283, 1097, 904, 800 and 755 nm, assigned to the transitions from the ground level to different excited levels of Dy3+ ions. The photoluminescence (PL) emission spectra of the glass system displayed three emission bands positioned at 482 (blue: 4F9/2 → 6H15/2), 574 (yellow: 4F9/2 → 6H13/2) and 664 nm (weak red: 4F9/2 → 6H11/2). For all the bands, the PL intensities of the studied glasses were more pronounced than singly embedded sample (either ANPs or TNPs). Furthermore, the enhancement in the PL peak intensity due to the inclusion of metallic NPs was attributed to the surface plasmon resonance mediated local field effect in the proximity of Dy3+ ions. Ligand bonding of Dy3+ showed the ionic nature of the prepared glasses. The absorption and emission spectral data were used to evaluate the J−O intensity parameters (Ωλ (λ = 2, 4, 6)) and radiative properties. Values of Ωλ (λ = 2, 4, 6) for glass with 0.1 mol% of TNPs exhibited the trend of Ω2>Ω6>Ω4 while all other glasses revealed Ω2>Ω4>Ω6. It was demonstrated that by combining two types of NPs (Ag and TiO2) hot spot with intense electromagnetic field could be created in the neighbourhood of Dy3+ ion to achieve enhanced optical attributes of the proposed glasses. The attainment of large quality factors and quantum efficiency (≈100%) in the ATNPs co−embedded glasses were established to be beneficial for the development of solid state lasers and other photonic devices.

Bound states in the continuum on periodic structures surrounded by strong resonances

Bound states in the continuum (BICs) are trapped or guided modes with their frequencies in the frequency intervals of the radiation modes. On periodic structures, a BIC is surrounded by a family of resonant modes with their quality factors approaching infinity. Typically the quality factors are proportional to $1/|\beta - \beta_*|^2$, where $\beta$ and $\beta_*$ are the Bloch wavevectors of the resonant modes and the BIC, respectively. But for some special BICs, the quality factors are proportional to $1/|\beta -\beta_*|^4$. In this paper, a general condition is derived for such special BICs on two-dimensional periodic structures. As a numerical example, we use the general condition to calculate special BICs, which are antisymmetric standing waves, on a periodic array of circular cylinders, and show their dependence on parameters. The special BICs are important for practical applications, because they produce resonances with large quality factors for a very large range of $\beta$.

Nearly bound states in the radiation continuum in a circular array of dielectric rods

We consider E polarized bound states in the radiation continuum (BICs) in circular periodical arrays of $N$ infinitely long dielectric rods. We find that each true BIC which occurs in an infinite linear array has its counterpart in the circular array as a near-BIC with extremely large quality factor. We argue analytically as well as numerically that the quality factor of the symmetry protected near-BICs diverges as $e^{\lambda N}$ where $\lambda$ is a material parameter dependent on the radius and the refraction index of the rods. By tuning of the radius of rods we also find numerically non-symmetry protected near-BICs. These near-BICs are localized with exponential accuracy outside the circular array but fill the whole inner space of the array carrying orbital angular momentum.

One-dimensional photonic crystal filter using a gradient-index layer

This work deals with a monochromatic filter which is designed using a symmetrical one-dimensional photonic crystals (1DPC) containing a gradient refractive index (GRIN) defect layer introduced in the center of the system. The results show that, by choosing some appropriate parameters of the defect layer such as the function of the refractive index and its geometric thickness, we are able to determine a high-performance monochromatic filter. The important obtained result is that we can obtain a very large quality factor of this filter by a GRIN function having the sinus form and the position of its transmission peak can be predefined by selecting the geometric thickness of the defect layer.

Quality factor assessment of finite-size all-dielectric metasurfaces at the magnetic dipole resonance

Recently there has been a large interest in achieving metasurface resonances with large quality factors. In this article, we examine metasurfaces that comprised a finite number of magnetic dipoles oriented parallel or orthogonal to the plane of the metasurface and determine analytic formulas for their resonances’ quality factors. These conditions are experimentally achievable in finite-size metasurfaces made of dielectric cubic resonators at the magnetic dipole resonance. Our results show that finite metasurfaces made of parallel (to the plane) magnetic dipoles exhibit low quality factor resonances with a quality factor that is independent of the number of resonators. More importantly, finite metasurfaces made of orthogonal (to the plane) magnetic dipoles lead to resonances with large quality factors, which ultimately depend on the number of resonators comprising the metasurface. In particular, by properly modulating the array of dipole moments by having a distribution of resonator polarizabilities, one can potentially increase the quality factor of metasurface resonances even further. These results provide design guidelines to achieve a sought quality factor applicable to any resonator geometry for the development of new devices such as photodetectors, modulators, and sensors.

Investigating on Through Glass via Based RF Passives for 3-D Integration

Due to low dielectric loss and low cost, glass is developed as a promising material for advanced interposers in 2.5-D and 3-D integration. In this paper, through glass vias (TGVs) are used to implement inductors for minimal footprint and large quality factor. Based on the proposed physical structure, the impact of various process and design parameters on the electrical characteristics of TGV inductors is investigated with 3-D electromagnetic simulator HFSS. It is observed that TGV inductors have identical inductance and larger quality factor in comparison with their through silicon via counterparts. Using TGV inductors and parallel plate capacitors, a compact 3-D band-pass filter (BPF) is designed and analyzed. Compared with some reported BPFs, the proposed TGV-based circuit has an ultra-compact size and excellent filtering performance.

Electromagnetic diode based on photonic crystal cavity with embedded highly dispersive meta-interface

In this paper, we propose a scheme for subwavelength electromagnetic diodes by employing a photonic crystal (PC) cavity with embedded electromagnetically induced-transparency (EIT)-like highly dispersive meta-interface. A nonreciprocal response, with 21.5 dB transmission light contrast and 12.3 dBm working power, is conceptually demonstrated in a microstrip transmission line system with asymmetric absorption and nonlinear medium inclusion. Such high-contrast transmission and relatively low-threshold diode action stem from the composite PC-EIT mechanism. This mechanism not only possesses a large quality factor and strong localization of fields but also does not enlarge the device volume and drastically reduce transmittance. Our findings should be beneficial for the design of new and practical metamaterial-enabled nonlinear devices.

Performance Limits of Luminescent Solar Concentrators Tested with Seed/Quantum-Well Quantum Dots in a Selective-Reflector-Based Optical Cavity.

Luminescent solar concentrators (LSCs) can serve as large-area sunlight collectors for photovoltaic devices. An important LSC characteristic is a concentration factor (C), which is defined as the ratio of the output and the input photon flux densities. This parameter can be also thought of as an effective enlargement factor of a solar cell active area. On the basis of thermodynamic considerations, the C-factor can reach extremely high values that exceed those accessible with traditional concentrating optics. In reality, however, the best reported values of C are around 30. Here we demonstrate that using a new type of high-emissivity quantum dots (QDs) incorporated into a specially designed cavity, we are able to achieve the C of ∼62 for spectrally integrated emission and ∼120 for the red portion of the photoluminescence spectrum. The key feature of these QDs is a seed/quantum-well/thick-shell design, which allows for obtaining a high emission quantum yield (>95%) simultaneously with a large LSC quality factor (QLSC of ∼100) defined as the ratio of absorption coefficients at the wavelengths of incident and reemitted light. By incorporating the QDs into a specially designed cavity equipped with a top selective reflector (a Bragg mirror or a thin silver film), we are able to effectively recycle reemitted light achieving light trapping coefficients of ∼85%. The observed performance of these devices is in remarkable agreement with analytical modeling, which allows us to project that the applied approach should allow one to boost the spectrally integrated concentration factors to more than 100 by further improving light trapping and/or increasing QLSC.