Tuning Elements Research Articles

An 18–28 GHz dual-mode down-converter IC for 5G applications

Emerging spectrum trends require a higher integration of 5G New Radio Frequency Range 1 (FR1) and Frequency Range 2 (FR2) bands to enhance the availability of spectrum and spectrum-sharing opportunities. To enable the reception of both FR1 and FR2 bands in a seamless hardware entity, we propose combining homodyne and heterodyne architectures. This necessitates the incorporation of a down-converter module that transfers the incoming signals from FR2 bands down to FR1, ensuring compatibility with an FR1 direct-conversion receiver (DCR) for the final signal reception. The primary focus of this paper is the design and implementation of the required integrated down-converter. The module includes an integrated balun, a low-noise amplifier (LNA) with a bypass mode, a dual-mode mixer, and an intermediate frequency (IF) amplifier. The introduced bypass mode helps to further elevate the linearity performance compared to the nominal mode. The bypass mode is designed for joint communication and sensing operation to avoid the compression of the receiver. This work also incorporates a local oscillator (LO) signal distribution network with phase tuning elements using a mixed-signal approach. The circuit is implemented in a 22-nm CMOS process, and the active die area is 0.6 mm2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext {mm}^\ ext {2}$$\\end{document}. The measurements demonstrate that the implemented chip can efficiently perform the required frequency conversion over a wide frequency range of 18–28 GHz. Conversion gain of 4.5–7.5 dB, noise figure of 15–19.7 dB, 1 dB compression point (IP1dB) of − 16 to − 10 dBm, and input third-order intercept point (IIP3) of − 5 to 0 dBm are achieved. The measured IP1 dB and IIP3 for the bypass mode are +0.5 to +4.5 dBm and +8.5 to +10 dBm, respectively.

Effect of zirconium oxide nanoparticles on thermal, optical, and radiation shielding properties of Bi2O3-B2O3-MnO2 glasses

This study has explored the DSC, UV–Vis absorption spectroscopy, gamma ray and neutron shielding properties of Bi2O3-B2O3-MnO2: ZrO2 glasses. It demonstrates a unique approach to photon shielding analysis using JENDL/PD-2016 photonuclear data and employs a validated spherical neutron model for neutron shielding. Five transparent glasses were prepared with the chemical composition (in mol%) of 29Bi2O3-70B2O3-(1-x)MnO2: xZrO2, and labeled as MZ0.00 (for x = 0), MZ0.25 (for x = 0.25), MZ0.50 (for x = 0.5), MZ0.75 (for x = 0.75) and MZ1.00 (for x = 1). The glass ceramic nature of the samples has been characterized by DTA thermograms. The glass forming ability parameters (Kgl, S & H) were found to be highest for the sample MZ1.00. The UV–Visible optical absorption spectra have been interpreted, and hence the cut-off wavelength (λcut-off) and optical band gap (Eo) were evaluated. The absorption spectra have revealed the co-existence of manganese ions in three stable valence states Mn4+, Mn3+ and Mn2+ in the samples. When ZrO2 nanoparticles were added in the composition up to x = 0.50 mol%, the red shift in the cut-off wavelength (λcut-off) with gradual shrinkage in optical band gap (Eo) has been observed. Also, the linear and non-linear optical parameters viz., refractive index (no), non-linear refractive index (n2), linear optical susceptibility (χ(1)) and non-linear optical susceptibility (χ(3)) have been evaluated. These parameters showcased that B-O, Bi-O, Mn-O, Zr-O, etc. bonds could be strengthened by subsequent reduction of polarization of the trivalent ions (B3+ ions, Bi3+ ions and Mn3+ ions) in the glass system at higher concentrations of ZrO2. Photoatomic and photonuclear attenuation studies portrayed that the sample MZ0.50 has the lowest photon shielding capability. The fast neutron effective removal cross section (ΣR) was observed to be the highest for the sample MZ1.00. Thus, these glasses can be used to design the thermally stable transparent glasses, tunable optical elements, and radiation shielding materials.

Inverse-designed flexural wave metamaterial beams with thermally induced tunability

Elastic metamaterials (EMMs) have been developed for more than two decades, but their practical applications have been scarcely reported due to their narrow bandgaps, relatively high working frequency ranges, poor load-bearing capabilities, and other implementation-related issues. As an attempt to solve some of these problems, in this work, a novel kind of tunable metamaterial beams is proposed to mitigate or isolate low-frequency and broadband flexural waves, where the integrated tunable elements made of a 3D-printed thermally sensitive material are inversely designed. The tunability is further achieved through the thermal-driving on the tunable elements. The optimized tunable elements are fabricated independently and have pretty good load-bearing capabilities under quasi-static uniaxial compression tests. They are directly glued on the host beams to form simple structured metamaterial beams without destruct the host beams. The experimentally measured transmission spectra under different thermal loadings demonstrate that the third pass-bands of the optimized three metamaterial beams at room temperature (RT) are changed to bandgaps or stop-bands as the temperature increases to about 60 °C, and vice versa. In addition, this temperature change induced bandgap is concatenated to the optimization obtained bandgap to form a wider bandgap. The good thermal reversibility is also validated by experimental tests under several thermal-loading cycles. Our present work suggests a dual-technique combined method to design low-frequency and broadband EMMs.

Tunable ultraviolet laser based on intracavity third harmonic generation of external cavity surface emitting laser

Ultraviolet laser has high frequency, short wavelength, large single-photon energy, and high spatial resolution, and has wide applications in many fields such as fine processing, life sciences, and spectroscopy. In this work, a wavelength tunable ultraviolet laser based on intracavity third harmonic generation from an external-cavity surface-emitting laser is reported. The W-type resonant cavity of the laser is composed of a distributed Bragg reflector (DBR) at the bottom of the gain chip, three plane-concave mirrors, and a rear plane mirror. On the arm containing the gain chip, a birefringent filter is inserted at the Brewster angle as the polarization and wavelength tuning element, which can also narrow the linewidth of the fundamental laser to a certain extent. A type-I phase-matched LBO crystal is placed on the beam waist between the folding mirrors M2 and M3 to convert the 980 nm fundamental laser into 490 nm blue light, and a type-I phase-matched BBO crystal is inserted in the beam waist near the rear mirror to produce a 327 nm ultraviolet output from the remained 980 nm fundamental laser and the frequency-doubled 490 nm second harmonic. Before the BBO crystal, a half-wave plate at 980 nm is employed to change the polarization of the fundamental laser, so as to meet the type-I phase-matching condition of the used BBO crystal. Owing to the larger nonlinear coefficient of the type-I phase-matched BBO crystal, and its obviously higher transmittance at 327 nm wavelength than the usually used LBO crystal, the output power is obtained to be 538 mW at 327 nm ultraviolet wavelength, corresponding to a conversion efficiency of 1.1% from pump light to ultraviolet laser. The experiment is performed under conditions of 15 ℃ temperature, 47 W absorbed pump power, 5 mm-length LBO and 5 mm-length BBO crystals. By using a 2 mm-thick birefringent filter as the tuning element, 34.1 nm tuning range of the 980 nm fundamental laser, 14.3 nm tuning range of the 490 nm second harmonic, and 8.6 nm tuning range of the 327 nm third harmonic are obtained. The ultraviolet laser exhibits good beam quality as well as acceptable power stability with the maximum power fluctuation less than 2% within 4.5 h.

Efficient Mesh Space Mapping Optimization for Tunable Filters Incorporating Structurally Simplified Coarse Mesh Model Without Tunable Elements

Efficient Mesh Space Mapping Optimization for Tunable Filters Incorporating Structurally Simplified Coarse Mesh Model Without Tunable Elements

Bandwidth-Enhanced Frequency-Agile Stacked Patch Antenna Sharing Common Tuning Element

Bandwidth-Enhanced Frequency-Agile Stacked Patch Antenna Sharing Common Tuning Element

Heterogeneous-IRS: A Green IRS Structure With Dynamically and Statically Tunable Elements

Heterogeneous-IRS: A Green IRS Structure With Dynamically and Statically Tunable Elements

Fabry–Perot Antenna Based on an Electrically Tunable Slot Antenna and a Two-Layer Frequency-Selective Surface

Introduction. One of the directions in Fabry–Perot antenna design consists in increasing its operation frequency range. In the present work, we set out to develop a Fabry–Perot antenna with a smooth gain pattern across a wide frequency range. To that end, a tunable slot antenna based on a thin-film ferroelectric varactor was used. The major development criterion was a high uniformity of the gain pattern, not exceeding 1 dB in the given frequency band. Aim. To develop a Fabry–Perot antenna for the 4.9–5.5 GHz frequency range with a high gain uniformity within the operating frequency band.Materials and methods. The antenna under development was based on thin-film ferroelectric capacitors as tunable elements. Fluoroplastic plates metallized on both sides were used as a dielectric material for manufacturing a frequency selected surface and a slot antenna. The parameters of ferroelectric elements were measured using a resonance technique, while the parameters of the dielectric material were determined using the Nicholson–Ross–Weir method.Results. The developed antenna has an operating frequency band of 4.9–5.5 GHz. Samples of ferroelectric capacitors and foiled dielectric material were manufactured and experimentally investigated. A tunable slot antenna was fabricated, and its characteristics were measured. The simulation results show that the gain value of the developed Fabry–Perot antenna is not less than 10 dB in the operation frequency range. Variations in the gain value within the operating frequency band do not exceed 0.7 dB.Conclusion. A Fabry–Perot antenna based on an electrically tunable slot antenna and a two-layer frequency-selective surface was developed. The operating frequency band of the developed device ranges within 4.9–5.5 GHz, which corresponds to the frequency band of Wi-Fi networks. Optimization of the antenna design parameters made it possible to achieve higher gain values under their minor variations in the operation frequency band.

Terahertz rewritable wavefront modulator based on indium oxide and DMSO-doped PEDOT:PSS.

An optically rewritable and electrically erasable terahertz (THz) wavefront modulator based on indium oxide (In2O3) and DMSO-doped PEDOT:PSS is proposed. The modulator has a three-layer structure of In2O3/PEDOT:PSS/quartz, which can weaken the THz transmission under the action of light excitation. Optically written THz Fresnel plates, which can focus the input Gaussian beam into a point, were realized. After optical excitation, the function of the device reduces slowly if it is stored in the room environment. However, the function can be stored for a long time if it is encapsulated in the nitrogen environment. If a bias voltage of 22 V is applied on the device, the function of the device can be erased in 10 seconds. The new function can be written into the device after wiping. Experiments on THz rewritable holographic devices are carried out to show the validity of this approach. This method can provide new devices for THz wavefront modulation and develop tunable optical imaging elements.

A bifunctional superconducting cell as flux qubit and neuron.

Josephson digital or analog ancillary circuits are an essential part of a large number of modern quantum processors. The natural candidate for the basis of tuning, coupling, and neromorphic co-processing elements for processors based on flux qubits is the adiabatic (reversible) superconducting logic cell. Using the simplest implementation of such a cell as an example, we have investigated the conditions under which it can optionally operate as an auxiliary qubit while maintaining its "classical" neural functionality. The performance and temperature regime estimates obtained confirm the possibility of practical use of a single-contact inductively shunted interferometer in a quantum mode in adjustment circuits for q-processors.

Effect of vacancy and pyridinic-like X-atom (X = Mg, B, C, and N) doping on the electronic and magnetic properties of antimonene: First-principles insights

We have explored the effect of vacancy and pyridinic-like X-atom (X = Mg, B, C, and N) doping on the geometries, electronic structure, and magnetism of antimonene (Sb) by means of first-principles calculations. The results showed that Sb with a single vacancy (SV-Sb) becomes a ferromagnetic metal with a moment of 0.33 µB. The X-atoms were doped at the edge site of the SV-Sb to form SV-nX-Sb (n = 1, 2, 3). All doped atoms except Mg form strong bonds with neighboring Sb-atoms. The stability of the designed structures was verified from formation energy (Efor). It was found that the SV-1X-Sb system is energetically more favorable (i.e. has the lowest Efor) for X = Mg, B, and C, while SV-3N-Sb is found more stable than SV-1N-Sb and SV-2N-Sb. Unlike metallic SV-Sb, the SV-1Mg-Sb, SV-1B-Sb, SV-1 C-Sb, and SV-3N-Sb structures exhibit semiconducting properties with a small band gap (of less than 0.5 eV). The ferromagnetism of SV-Sb is retained for X = B, and N doping, whereas Mg and C doping turned SV-Sb to non-magnetic, caused by the reconstruction of the edge Sb/X atoms. In addition, selective doping significantly altered the work function of the host material. These findings suggest the potential use of non-magnetic elements for tuning the electronic and magnetic properties of the monolayer antimonene for extended applications.

A magnetorheological vibration absorber with bidirectional tunability for pipelines

A magnetorheological elastomer (MRE) is employed as a tunable stiffness element in a dynamic vibration absorber (DVA) due to its remarkable magnetic tunability. However, the natural frequency of the MRE-based DVA can only be tuned towards high frequency under magnetic fields, which fails to solve, or even exacerbates, the low-frequency pipeline vibration. To tackle this issue, an innovative DVA (H-DVA) with bidirectional magnetic tunability is proposed in this paper. The hard magnetic MRE filled by NdFeB particles is selected as the core tunable stiffness element in H-DVA. Besides, the discretization distribution design scheme for the mass oscillators is adopted to improve the flexibility of H-DVA. Then, the magnetic field simulation and resonance frequency shifting test of H-DVA under different magnetic fields are completed to validate the bidirectional magnetic tunability. Lastly, the vibration absorption effect is verified in a self-established experimental pipeline system. The experiment results demonstrate that the resonance frequency of the proposed H-DVA exhibites a maximum frequency shift of approximately −2.7 Hz under reversed magnetic field. Compared to H-DVA working in zero field state, the acceleration magnitude of the pipeline vibration is further reduced by 8.8% when applying −1.5 A to the H-DVA under 55 Hz excitation. Similarly, the acceleration magnitude is further reduced by 22.2% when applying 2 A to the H-DVA under 85 Hz excitation. Thus, these findings confirm that the H-DVA proposed in this paper not only achieves the bidirectional magnetic tunability, but also improves the vibration absorption effect for pipeline vibration.

A Review of Progress about Birefringent Filter Design and Application in Ti:sapphire Laser

All-solid-state tunable lasers have been widely used in many fields including multi-photon microscopy, time-resolved photoluminescence, atomic physics, and so on owing to their broadband output spectrum range, good beam quality, and low noise. To cover the broad fluorescent line of the laser crystal as much as possible, a birefringent filter (BRF) is always the most popular candidate for acting as a tuning element. In this review, the tuning characteristics of BRF and the design rule as well as its progress in practical application are summarized. Especially, it is worth noting that laser crystal itself begins to act as the BRF for wavelength tuning except for its gain characteristic, which has paved a new way for developing a kind of novel tunable laser. We believe that this review will not only provide a valuable reference for the design of BRF but also lay the foundation for developing a new application of BRF.

Some Practical Applications of Discretely Tunable Couplers’ Matrix Model

The findings of a research of the practical application of a previously developed model of a decametric waves discrete coupler are presented. Due to the high accuracy achieved in describing the transforming properties of Coupler in the operating frequency range, together with the apparatus of the theory of complex variables, in particular with the method of conformal maps of fractional linear functions, it was possible to solve a number of applied problems. A method for calculating the area of consistent loads of discretely tunable power circuits of arbitrary structure has been developed. For completeness of the result, the case of matching a generator with a complex value of internal resistance with a given quality (with an acceptable value of the traveling wave coefficient) has been considered. The proposed approach to matching assumes that for any possible antenna load there must be appropriate combinations of discretely tunable elements of the Coupler power circuit that ensure matching with a given quality. The design ratio for images of arbitrary circles and straight lines conformally mapped by a matching quadrilateral to a given complex domain (i.e., expressions for calculating the coordinates of the circle center and its radius, as well as coefficients of the equation of straight lines) has been obtained. Studies of the matching properties of various circuits implemented on discrete elements have been carried out. The results of this study are important when choosing the structural design of the Coupler power circuit. Calculation formulas are obtained that allow us to estimate the relative losses of active power in the Coupler power circuit. This contributes to the reasonable choice of the best configuration option from several, similar in quality matching, thereby avoiding complicated temperature settings of the circuit elements. An exhaustive search method of tuning the discrete contour of the Coupler has been proposed, which is extremely simple and does not require heavy calculations with matrices and complex numbers.

Active Metasurfaces for Non‐Rigid Light Sail Interstellar Optical Communication

AbstractThe non‐rigidity of the nanophotonic metasail platform and the intense imparted optical force from the terrestrial laser source lead to deformations during the propulsion stage. These deformations must be taken into consideration due to their potential adverse impact on communication performance. Alterations in the shape of the sail body result in varying angles of incidence and polarization components observed by the photonic unit cell, significantly impacting their intended performance. Based on this premise, this paper proposes utilizing a reflective all‐dielectric, low‐power active metasurface that dynamically compensates for the effects of deformation and facilitates beam‐steering for communication purposes among different light sails in interstellar space. Configured as p‐n multi‐junction layers, the constituent elements of the metasurface enable modulation of carrier concentrations through multigate biasing. Through electrostatic simulations, it demonstrates that the required permittivity modulation of can achieve a wide phase span of 320°. Furthermore, it has investigated the effect of the presence of non‐functional portions in the far‐field radiation pattern of the light sail and highlighted the critical role of tunable elements in mitigating its impact. The obtained results hold great promise for realizing successful interstellar downlink communication between such gram‐scale nano‐crafts and Earth.

Silicon Programmable Photonic Circuits Based on Periodic Bimodal Waveguides

AbstractProgrammable photonic circuits are dense assemblies of waveguide meshes in which the flow of light can be reconfigured by software to implement a wide variety of functions, ranging from radiofrequency filtering to optical computing. However, most programmable architectures to date rely on rather bulky Mach‐Zehnder interferometers (MZIs), which are not suitable for large‐scale and high‐density integration. Here, an alternative approach to MZI‐based programmable photonic circuits by using slow‐light‐enhanced periodic bimodal waveguides (PBWs) as programmable units is presented. This study experimentally demonstrates low‐loss short tuning elements of 30× 1.7 µm2 in area, achieving a two‐orders of magnitude integration density improvement compared to conventional MZIs. A rectangular arrangement of these tunable units is proposed for 3× 3 and 4× 4 matrix multiplication operations to design a feedforward circuit with a footprint of only 100× 250 µm2. Finally, the performance trade‐off and benchmark with alternative programmable unit cells are analyzed in order to address the ever‐growing demand for large computing requirements in next‐generation applications such as artificial intelligence and quantum information processing.

Continuous beam steering with a varactor-based reconfigurable intelligent surface in the Ka-band at 31 GHz

Varactor diodes have been proposed as active tuning elements of reconfigurable metasurfaces in the Ka-band. However, their experimental realization in this frequency range has not been demonstrated yet. We report the implementation of such a reconfigurable intelligent surface (RIS) made of 20×20 unit cells. By active tuning of the bias voltage of the varactors, the phase of the backward diffracted wave can be continuously tuned between 0° and 180°. Thus, the phase tuning can be independently controlled for each unit cell. The frequency working range of the RIS is 1.1 GHz (from 30.6 to 31.7 GHz). As an illustration of the practical use, we demonstrate continuous beam steering of microwave radiation at 31 GHz in a defined propagation plane.

An Automated Router With Optical Resource Adaptation

Photonic Integrated Circuits are rapidly becoming more reconfigurable using tunable waveguide elements, coming closer to realizing ‘general purpose’ programmable waveguide meshes. To utilize the full potential of such circuits, special software routines need to be developed to determine the optical paths inside the mesh. Right now, current methods either scale exponentially in problem size or are severely lacking performance-wise, largely unable to find solutions, especially in recirculating waveguide meshes with square or hexagonal unit cells. We present an algorithm that computes an efficient configuration that correctly routes all given signals. Whereas similar papers look at meshes containing 7 to 20 hexagonal cells, in this paper, meshes of up to hundreds of hexagonal cells are considered. We compare the results of our algorithm to an earlier proposed algorithm and to an optimal solution. Several parameters are introduced in the algorithm. These are studied and an optimizer is implemented to determine effective values for them.

Advancing IoT wireless sensor nodes with a low profile multiband RF rectifier based on multi-stub J-Inverter network

In this paper, a unique RF rectifier design is introduced, employing a multi-stub J−Inverter impedance matching network (IMN). The structure of the IMN comprises a series of three sections with multiple stub tuning elements interconnected via a meandered line (MDL) to form multi-frequency susceptance blocks. The rectifier has been developed to work at frequency bands: 1.84, 2.10, and 2.45 GHz. These frequencies align with the designated bands for GSM/1800, UMTS/2100, and Wi-Fi, respectively. By implementing a complete ground architecture, the rectifier utilizes a minimal space of 0.57λg×0.3λg on the RT/Duroid 5880 PCB board. The experiment’s outcomes show the proposed RF rectifier’s effectiveness in converting radio frequency (RF) signals into direct current (DC) power (RF-to-DC). The results indicate PCE values of 32.70%, 27.60%, and 24.50%, corresponding to input powers of -20 dBm at the targeted operational frequencies. Additionally, the rectifier design proposed within this study achieves its peak RF-to-DC PCE of 75.30% when energized by an input power of 3 dBm. Moreover, notable stability is demonstrated by the rectifier, sustaining an RF-to-DC PCE surpassing 50% throughout the frequency range spanning 1.7 to 2.4 GHz. This robust performance remains consistent even at lower input power levels, such as -10 dBm Furthermore, the rectifier can produce a direct current (DC) voltage output ((VDC)), measured at 0.411 V in an ambient context. The integration of the rectifier with the power management module (PMM), facilitated through the utilization of the bq25504-674 evaluation module (EVM), successfully established a connection within the PMM system. This integration yielded a (VDC) of 1.270 V. Hence, through proficient management of the proposed RF rectifier, it becomes feasible to utilize ambient RF signals to energize a range of low-energy devices effectively.

A Tunable Gain Microstrip Antenna for Compact Pattern-Reconfigurable Array

In this letter, a method of tunable gain microstrip antenna for compact pattern reconfigurable array is proposed. The tunable gain element is realized by integrating a switchable resistive attenuator which is composed of a RF SP4T and four loading resistors. The method is demonstrated on a 6-element sidelobe reconfigurable array operating at 2.45 GHz which consists of three kinds of tunable gain elements with different gains. The measurements have a good agreement with the simulations and show the first sidelobe level (SLL) range from -14 dB to -20 dB of the array at 2.45 GHz in H-plane is achieved based on the tunable gain range from 5 dBi to 1.9 dBi of the elements.