Modification of a silicon surface visible light reflectivity by the carbon nanofilm

Crystalline silicon substrate visible light reflectivity is finely modified by a discrete growth of carbon nanofilm (CNF) on it by nanosecond pulsed laser deposition (PLD) technique. It is established that 71 nm thick CNF effectively reduces the high reflection of the substrate on average to 5% in the visible light wave range. The exact values of the thickness and refractive index of the carbon nanofilm are also determined via an analysis of reflection spectra.

Quality of radiation conversion under four-wave mixing on thermal nonlinearity with feedback

Quality of radiation conversion under four-wave mixing on thermal nonlinearity with feedback for both signal and object waves has been investigated at high reflection coefficients. It has been shown that the optimal operating mode of a four-wave converter on thermal nonlinearity is the mode in which the pumping waves have equal intensities and there is a compensation for a phase shift arising from the pumping wave self-action. In this operating mode of the four-wave radiation converter, as compared with the case of the absence of feedback for both signal and object waves, a significant increase in the amplitude reflection coefficient is observed with an increase in the pumping waves intensities. In this case, despite the decrease in the bandwidth of spatial frequencies of the object wave with an increase in the pumping wave intensities, the quality of radiation conver-sion with feedback for both signal and object waves is better than in the absence of feedback.

Reflectarray Resonant Element based on a Dielectric Resonator Antenna for 5G Applications

The performance of a proposed cross hybrid dielectric resonator antenna (DRA) element for dual polarization configuration operating at 26 GHz for 5G applications is presented in this paper. The new cross hybrid DRA unit cell is introduced which combines a cross shape DRA with a bottom loading cross microstrip patch. This technique of a bottom loading cross microstrip patch is chosen as the tuning mechanism (varying the length of the microstrip to tune the phase) instead of changing the DRA dimensions because of their ease of implementation and fabrication. By doing so, high reflection phase range with low reflection loss performance can be obtained, which is essential for a high bandwidth and high gain reflectarray for 5G applications. The design and simulation have been done using commercial software of CST MWS. The reflection loss, reflection phase and slope variation were analyzed and compared. A metallic cross microstrip patch of varying length placed beneath the DRA to act as the phase shifter to tune the phase and give smooth variation in slope with a large phase range. The proposed cross hybrid DRA unit cell provides a high reflection phase range of 342º and 1.8 dB reflection loss. The computed results are compared with experimental results revealing reasonable agreement, thereby confirming the viability of the design.

Optical bistability in reflection from multilayer metal-dielectric structure with Kerr nonlinearity

Both static and dynamic characteristics of light reflected from a specially designed multilayer metal-dielectric structure with Kerr nonlinearity have been studied in this work. Various regimes of nonlinear reflection from the structure have been demonstrated, including bistable switching between low and high reflection states, which occurs at low intensity of the incident light due to a significant enhancement in the optical field in the nonlinear layer under conditions of total internal reflection. This nonlinear structure has been proposed to use as an optically controlled intracavity laser modulator.

Synthesis Polymer Matrix Composite Epoxy-FeNdB-Mn for Radar Absorbing Material Application

<p style="margin-bottom: 0in; line-height: 115%;" align="justify"><span style="font-family: Times New Roman, serif;">In recent years, applications using electromagnetic wave technology have grown rapidly. One of them is in the military field, the wave-absorbing material used to avoid detection such as aircraft, ships, or tanks requires a super thin absorbent material which has extraordinary absorption. One of the criteria for a wave absorbing material is a soft magnet and has a high Reflection Loss (RL). This research aims to see the effect of the addition of FeNdB and Mn on the synthesis of Polymer Matrix Composite (PMC) as a wave-absorbing material.</span><span style="font-family: Times New Roman, serif;">The FeNdB milling process and Mechanical Alloying (MA) with Mn were carried out using a Planetary Ball Mill (PBM) at a speed of 1000 rpm for 60 minutes. synthesis of PMC by varying the composition of epoxy resin with magnetic powder 95: 5; 90:10; 85: 5. Based on the characterization results, the optimum RL was obtained at a composition of 85: 5 with a value of -22.40 dB at a frequency of 10.40 GHz and the magnetic properties after the addition of Mn were obtained HcJ 0.116 kOe and Br 0.41 kG. PMC hardness increased with the increase of powder in the sample with the highest value of 29.2 HD Shore D and the adhesion decreased with the addition of powder in the sample with the lowest value of 1 MPa.</span></p>

Broadband ventilated metamaterial silencer for high reflection based on Fano-like interference

Conventional sound shielding structures is difficult to meet the requirements of low-to-middle frequency broadband sound insulation and free ventilation. In this paper, we propose a ventilated metamaterial silencer based on Fano-like interference, which can achieve the sound transmission loss (STL) of more than 10 dB in the range of 516–970 Hz with subwavelength thickness (0.11 [Formula: see text]) while remains an opening area ratio of 23%. The designed silencer is composed of a large central orifice and four surrounding coiling channels, making the sound waves passing through the two areas generate Fano-like asymmetric transmission spectrum and form efficient reflection to insulate sound coming from various directions. The parametric studies are also carried out to investigate the tunable acoustic performance. Experiment measurement matches well with the simulation results. In the future, the proposed silencer may have potential applications in practical environments requiring broadband sound insulation and free air flows.

Multimodality Image Analysis in a Cohort of Patients with Atypical Juvenile Ocular Toxocariasis

Purpose. To analysis the multimodal imaging of a group of patients diagnosed clinically with atypical juvenile ocular toxocariasis (OT). Methods. In this case series study, we examined 9 young patients diagnosed with atypical OT. Routine ophthalmological examinations, fundus photography, optical-coherence tomography (OCT), fluorescein angiography (FFA), and B-mode ultrasound were performed. A questionnaire was used to record whether the patients were newly diagnosed and whether they had a history of exposure to a cat and dog. Aqueous humor and serum samples were taken for serological tests. Results. In all the patients, yellow-and-white dot-shaped lesions and perivascular white sheath were seen in the fundus. Heterogeneous changes including hyper-reflection in the disrupted neuroretina, hyper-reflection in the outer retinal layer, high-reflection mass on the surface of the neuroretina accompanied with reflective attenuation, and high-reflection mass involving the entire neuroretina or high-reflection mass in the vitreous body were noticed in OCT images. On FFA, seven of these patients (77.8%) showed leakage of fluorescein in the small- and medium-branch veins of the retina, and a “bristle-like” change indicated increased permeability of the vessels. B-mode ultrasound showed proliferative membranes and proliferative bands (33.3%), as well as spotted opacity in the vitreous (66.7%). The antibodies to Toxocara canis in the aqueous humor and serum were positive, and the Goldmann–Witmer coefficient was significantly increased in 6 out of 7 patients. Conclusions. Multimodality images are useful in the diagnosis of atypical juvenile OT, which could be easily overlooked and misdiagnosed.

Tunable Omnidirectional Band Gap Properties of 1D Plasma Annular Periodic Multilayer Structure Based on an Improved Fibonacci Topological Structure

In this paper, the characteristics of the omnidirectional band gap (OBG) for one-dimensional (1D) plasma cylindrical photonic crystals (PCPCs) are based on an improved Fibonacci topological (IFT) structure are studied. The influences of the azimuthal mode number, incident angle, plasma thickness, and plasma frequency on the OBG are discussed. It is concluded that increasing the azimuth modulus can significantly expand the bandwidth of the OBG, and the OBG can be moved to the low-frequency direction by increasing the plasma frequency. In addition, an interesting phenomenon can be found that when the number of azimuthal modes is equal to 2, the TM wave can produce an extra high reflection zone. It provides a theoretical support for designing the narrowband filters without introducing any physical defect layers in the structure.