Microwave phased array antennas (PAAs) have great importance on electromagnetic detection due to their ability to control complex beam patterns and multiple beamforming. Analog PAAs require microwave phase shifters for phase controlling of antennas; However, these systems cause the beam-squint problem in the radiation pattern of the antennas and thus limit the bandwidth. Among the solutions proposed for this problem, the true-time delay (TTD) technique based on photonic delay circuits shows better emission loss factors and bandwidth. In photonic TTD circuits, phase modulator systems play one of the most important functions in the transmission of microwave to photonic signals. In this paper, a low noise and high modulation bandwidth system is designed and fabricated for long-term stable laser current modulator performance. The laser current modulator system designed and built in this paper has long-term thermal stability of 1.6 ppm/°C, repeatability of 31.7nA, a modulation response greater than 10 MHz, and time response to load impedance changes of 67 nS. After building an optical modulator circuit to investigate the behavior of this modulator in a PAA system based on TTD, the data related to the impedance response time of this circuit is modeled as a Gaussian function in the frequency domain and have been investigated and simulated along with other components models of a TTD system to obtain the optimal characteristics of a modulation spectral shaper. Based on the characteristics required for the modulation spectral shaper, a fiber optic booster with specific dispersion and nonlinear coefficients is innovatively introduced. The results of the modulator-booster integration indicate the reduction of distortion and lower power consumption in the frequency spectrum and radiation patterns of the transmitted and received signals of the antenna array.
Spinel zinc orthotitanate (Zn 2 TiO 4 ) has attracted considerable attention as a promising semiconductor photocatalyst. Zn 2 TiO 4 and Zn 1.85 M 0.15 TiO 4 (M = Cu 2+ , Ni 2+ , Co 2+ , and Mg 2+ ) were synthesized via a two-step solid-state reaction method. Their structural, morphological, optical, and photocatalytic properties were systematically examined to evaluate the influence of metal-ion doping. XRD spectroscopy confirmed that all the prepared materials formed a cubic structure with the impurity of ZnO. The crystallite sizes of the prepared materials were in the nanometer range (40.41–45.65 nm). Morphological FESEM analysis revealed spherical-shaped particles, while EDS analysis confirmed the presence and homogeneous distribution of the constituent elements. HRTEM analysis further verified the crystalline nature of the materials through clear lattice fringes and corresponding d-spacing values. FTIR analysis confirmed the presence of functional groups associated with Zn-O and Ti-O bonding. The synthesized materials exhibited optical activity in the ultraviolet region. UV–Vis analysis demonstrated that metal-ion incorporation enhanced visible-light absorption and reduced the optical band gap energy from 3.22 eV for pristine Zn 2 TiO 4 to 2.70 eV for Co-doped Zn 2 TiO 4 . Photoluminescence analysis indicated that doping influenced the recombination behavior of photogenerated charge carriers. The photocatalytic activity of the samples was tested using MB dye under UV irradiation. The highest degradation efficiency was 92.23%, and this was achieved for the sample Zn 1.85 Ni 0.15 TiO 4 , confirming that doped Zn 2 TiO 4 is a promising photocatalyst for environmental remediation applications.
Spinel zinc orthotitanate (Zn2TiO4) has attracted considerable attention as a promising semiconductor photocatalyst. Zn2TiO4and Zn1.85M0.15TiO4 (M = Cu2+, Ni2+, Co2+, and Mg2+) were synthesized via a two-step solid-state reactionmethod. Their structural, morphological, optical, and photocatalytic properties were systematically examined to evaluate the influence of metal-ion doping. XRD spectroscopy confirmed that all the prepared materials formed a cubic structure with the impurity of ZnO. The crystallite sizes of the prepared materials were in the nanometer range (40.41–45.65 nm). Morphological FESEM analysis revealed spherical-shaped particles, while EDS analysis confirmed the presence and homogeneous distribution of the constituent elements. HRTEM analysis further verified the crystalline nature of the materials through clear lattice fringes and corresponding d-spacing values. FTIR analysis confirmed the presence of functional groups associated with Zn-O and Ti-O bonding. The synthesized materials exhibited optical activity in the ultraviolet region. UV–Vis analysis demonstrated that metal-ion incorporation enhanced visible-light absorption and reduced the optical band gap energy from 3.22 eV for pristine Zn2TiO4 to 2.70 eV for Co-doped Zn2TiO4. Photoluminescence analysis indicated that doping influenced the recombination behavior of photogenerated charge carriers. The photocatalytic activity of the samples was tested using MB dye under UV irradiation. The highest degradation efficiency was 92.23%, and this was achieved for the sample Zn1.85Ni0.15TiO4, confirming that doped Zn2TiO4 is a promising photocatalyst for environmental remediation applications.
An RF-driven Josephson weak link can retain a measurable response maximum after that maximum ceases to identify the first Shapiro-step voltage. We reanalyse archived antenna-coupled YBCO measurements using a branch-paired, continuity-aware framework that separates symmetric voltage detuning from common-mode offset and permits an explicit non-identifiable outcome. The source archive comprises 181 TXT entries; the preserved analysis cohort contains 134 distinct RF-exposed records. At 155 GHz, Device A retains paired errors of 0.467–0.539% from 10 to 50 K, develops a 3.481% paired displacement at nominal 60 K, and yields no defensible first-step assignment in ten standard-frequency records at nominal 70 K despite persistent maxima. Device B remains identifiable at all 15 nominally matched temperature–frequency conditions and in 14/14 available nominal-70 K RF records (0.560% RMS error). Across 20 documented sensitivity settings, the broad condition-level interpretation is maintained, with two isolated false-positive acceptances under stress settings. A constrained overlapping-response reconstruction reproduces the displaced maximum, while fits to native acquired I–V samples also admit a flexible asymmetric single-response description; the microscopic decomposition is not identified. The results establish a practical distinction between detecting a maximum and assigning an identifiable Shapiro-step voltage, while documenting the uncertainty and configuration-comparison limits of the historical measurements.
The present article included organic light photodetectors (OPDs) based on Poly(vinyl alcohol) (PVA) supported with fluorescein (FLOs) and graphene nanosheets (GNs), and FLOs-supported PVA was fabricated and investigated. Two discs, one of FLOs/PVA (W) and the other of FLOs + GNs/PVA (G), each 2 um thick, were prepared by pouring the solution onto a clean Petri dish. Silver electrodes were deposited on them and used as photodetectors. It was found that adding of GNs shortened the rise and recovery times of the fabricated OPDs under visible-light illumination. The optical band gap [ Eg] decreases with FLs + GNs/PVA, ranging from 4.03 eV for FLs /PVA to 3.97 eV for FLs + GNs/PVA. The response was over a wide range of wavelengths (325–700 nm). with a −5V, 0 V and 5 V applied bias and 325–750 nm visible light illumination, the high responses of the W and G OPDs are 75.5 and 228.5, respectively . The quantum efficiency versus the luminous intensity of the two photodetectors indicated that of G OPDs is better than with W OPDs (EQE = 20–28% implies light intensity 25 mW/cm2 under measurement at a forward bias of 5 V). In addition, the other prepared material was used to study their thermometric measurements. FLOs/PVA and FLOs + GNs/PVA discs of 4 um thickness were prepared by the casting method. The thermal measurements of the discs were examined and compared with those of a pure PVA disc. It was observed that adding FLOs dye increased thermal conductivity, whereas adding GNs enhanced it.
