Back Plane Research Articles

Bandwidth enhancement of resonating absorber using a lossy dielectric layer for RCS reduction in X-band

Abstract In this paper, a resonating absorber is proposed for radar cross section reduction in the X-band, with the inclusion of a high loss dielectric layer. The absorber consists of a pair of co-centered resonating Jerusalem cross printed on a FR4 substrate cascaded with a high-loss dielectric layer and a metallic back plane. The designed absorber offers 90 % absorption from 7.8–12 GHz with a fractional bandwidth of 42.42 %. The designed absorber is 0.106λ L thick with a compact square unit cell of size 0.076λ L (wavelength at the lowest frequency). An equivalent circuit model is developed to analyze the proposed absorber. The absorber is angularly stable for varying angle of incidences up to 40°–60° for TE and TM polarizations respectively. The planar as well as the conformal structure of the proposed absorber offer a minimum 10 dB radar cross section reduction in the X-band. The conventional approach which involves complex fabrication process of soldering thousands of lumped resistors to increase the bandwidth, whereas the proposed absorber is realized to offer wide absorption using simple PCB etching technique. To validate the design prototype is fabricated and the measurement is carried out.

Optical quantization of carbon-incorporated polysilicon and its potential application in photovoltaic devices

The polysilicon (poly-Si) in tunnel oxygen passivated contact (TOPCon) structures delivers outstanding passivation performance; nevertheless, it also introduces some level of parasitic absorption, particularly noticeable in the medium and long wavelength bands. Here, we synthesized carbon (C)-incorporated poly-Si by introducing carbon into poly-Si through the plasma enhanced chemical vapor deposition (PECVD) method, aiming to mitigate parasitic absorption. Our focus was on investigating the impact of parameters such as C content and annealing temperature on the optical properties of poly-Si, including the refractive index and extinction coefficient. Additionally, we calculated the free carrier absorption (FCA) through the reflectance and transmittance of the material. It is found that the FCA in the long wavelength band decreases with increasing C incorporating, while it increases with higher annealing temperature. Furthermore, simulations revealed that the parasitic absorption of C-incorporated poly-Si (with the CH4/SiH4 flows ratio of 3) in the back plane of TOPCon cells is approximately 0.38 mA/cm2 per 100 nm, less than 0.52 mA/cm2 per 100 nm from the conventional poly-Si. Therefore, the results show the advantages of C-incorporated poly-Si in optical properties.

High Quality Carbon Nanotube Thin Films for Transistor Application

Semiconducting carbon nanotubes (s-CNTs) are promising channel materials for both high-performance ultra-scaled field-effect transistors (FETs) and thin film transistors (TFTs) due to their excellent electronic properties. Many research groups have demonstrated the application of s-CNTs in either logical computing circuits or large area electronics. However, before the CNT-based electronics technology takes real impact, many challenges should be overcome, such as achieving high purity of s-CNTs, reliable methods for their deposition and alignment, development of scalable and cost-effective production techniques, and corresponding quality characterization metrology. In this presentation, we will report our progress on the s-CNT materials and their application for FETs and TFTs.Conjugated polymer wrapping method was used to extract s-CNTs from the raw CNT materials. We have developed a closed-loop recycling strategy, in which raw materials (CNTs and polymers) and solvents were all recycled and reused for multiple separation cycles, thus high-purity (99.9999%) and high structural quality s-CNTs were mass produced. The cost was reduced to ~ 1% in comparison with commercially available products, and total yield was increased to 36% in comparison with 2%–5% of usual separation methods.Highly unform and density-controllable thin films of random-oriented CNTs (R-CNTs) were fabricated by a dip-coating method on 4-inch/8-inch Si wafers and 2.5th generation (G2.5) backplane glasses (370 mm × 470 mm). Ultra-clean wafer-scale aligned s-CNTs (A-CNTs) were fabricated by a modified dimension-limited self-alignment (m-DLSA) method. To quantify the overall quality of both R-CNT and A-CNT films, we proposed a four-parameter metrology which includes the local tube density (DL), global density uniformity (Cv), local degree of order (OL), and the relative tube proportion in a certain orientation (Pθ) at a location. The four-parameter metrology is not only powerful for overall quality evaluation of CNT films, but also able to predict the performance fluctuation of fabricated devices.TFTs fabricated using the R-CNTs show mobility of 45-55 cm2/Vs with a high-performance uniformity (Cv ≈ 11%–13%) on a 4-inch wafer. A micro-LED display with 32×32 pixels were driven successfully by 2T1C AMTFT back plane based on R-CNT TFTs. Top-gated FETs based on A-CNTs exhibit excellent electronic performance with an on-state current (Ion) of 2.2 mA/μm, peak transconductance (gm) of 1.1 mS/μm, low contact resistance (Rc) of 191 Ω•μm and negligible hysteresis, among the best reported performance of CNT FETs. We believe our progress in the s-CNT materials will greatly push the CNT-based electronics technology into practical applications.

Distinguishing the topological charge of vortex beam via Fourier back plane imaging with chiral windmill structure

In recent years, research on the interaction between orbital angular momentum (OAM) of light and matter has shown a continuous influx of investigations. OAM possesses distinct properties, such as a degree of freedom with multiple states, vortex characteristics, and topological properties, which expand its applications in optical communication, optical sensing, and optical manipulation. We have observed different phenomena in the chiral metal windmill structure under excitation of spin angular momentum (SAM)-OAM beam generated by Q-plate than under SAM excitation. Fourier back focal plane (FBP) imaging under SAM beam excitation easily identifies the chirality and geometric properties of the structure. When the SAM-OAM beam excites the structure, FBP not only identifies its chirality and geometric properties but also distinguishes different OAM topological charges and signs, as well as the degree of elliptic polarization. The Stokes parametric FBP imaging reveals asymmetric polarization distribution resulting from the interaction between a vortex beam and the chiral structure. Moreover, it clearly reflects the conversion process of SAM to OAM. The experimental results match well with simulation results. These findings hold valuable insights for the advancement of optical information storage and communication using OAM, opening up new possibilities for further exploration in this field.

Optimization of an electric field calibration chamber for high-precision measurements for imaging applications

The DEVCOM Army Research Laboratory (ARL) electric field “cage” generates a uniform E-field over a large working volume, along the lines of the IEEE-Std 1308–1994. The end plates are spaced farther apart than the IEEE standard field source, and the fringing fields are controlled by the addition of “guard tubes.” This chamber was originally constructed to calibrate and characterize electric field sensors, and it has been redesigned to support quasi-static electric field imaging applications. A planar array of sensors forms a grounded end plate of the cage and is used to measure distortions in the uniform field generated by the cage due to objects placed inside. However, the array itself distorts this field and introduces significant errors. Several modifications were made to mitigate the errors, including adding nonfunctional “dummy” elements, a border around the array, and a back plane behind it. The parameter space for these additions is very large, since the number of nonfunctional elements, the width of the border, and the size and placement of the back plane can all be tuned independently. Extensive computer modeling was used to explore this parameter space and test thousands of possible designs. The design chosen yields modeled absolute field errors over a 1.2-m × 0.8-m sensing plane that are less than 0.5 % for a uniform ambient field (empty cage), and less than 1 % for a sphere with a 0.5-m radius in an ambient field.

14‐1: A Study on Flexibility Improvement of AMOLED Back Plane and Mask Reduction Process Architecture Using Photo‐sensitive Organic Insulation Films

In this work, the method of patterning inter‐layer deposition (ILD) and passivation layer (PVX) of the AMOLED back plane structure with an organic film was studied. By replacing the inorganic film of SiNx + SiO2 with an organic film Poly‐imide, back plane suitable for flexible AMOLED was secured. It was possible to secure equivalent TFT transfer characteristics of device compared to inorganic inter layer structure by applying low‐temperature buffer and 2nd gate insulator SiNx to the organic inter layer TFT device. Also, VIA + passivation layer 2 mask photo process was replaced with 1 mask photo process using a VIA Half‐tone mask. Both processes were able to secure a process architecture that can be applied to flexible and rollable displays in the future by using photo‐sensitive organic insulation films.

Smartphone-based optical sectioning (SOS) microscopy with a telecentric design for fluorescence imaging.

We propose a smartphone-based optical sectioning (SOS) microscope based on the HiLo technique, with a single smartphone replacing a high-cost illumination source and a camera sensor. We built our SOS with off-the-shelf optical, mechanical cage systems with 3D-printed adapters to seamlessly integrate the smartphone with the SOS main body. The liquid light guide can be integrated with the adapter, guiding the smartphone's LED light to the digital mirror device (DMD) with neglectable loss. We used an electrically tuneable lens (ETL) instead of a mechanical translation stage to realise low-cost axial scanning. The ETL was conjugated to the objective lens's back pupil plane (BPP) to construct a telecentric design by a 4f configuration to maintain the lateral magnification for different axial positions. SOS has a 571.5µm telecentric scanning range and an 11.7µm axial resolution. The broadband smartphone LED torch can effectively excite fluorescent polystyrene (PS) beads. We successfully used SOS for high-contrast fluorescent PS beads imaging with different wavelengths and optical sectioning imaging of multilayer fluorescent PS beads. To our knowledge, the proposed SOS is the first smartphone-based HiLo optical sectioning microscopy (£1965), which can save around £7035 compared with a traditional HiLo system (£9000). It is a powerful tool for biomedical research in resource-limited areas.

Improvement of the Bias Instability Characteristics Driven by Organic Film in IGZO TFT for OLED Back Plane

Improvement of the Bias Instability Characteristics Driven by Organic Film in IGZO TFT for OLED Back Plane

Modification of transformer coupled permeameter for frequency extension

A broadband and high-sensitivity permeability measurement system that covers 10 MHz–20 GHz was previously developed and named the transformer coupled permeameter (TC-Perm). This paper describes the modifications of the TC-Perm system to further extend the operation frequency range on both the high and low frequency sides. In the previous system, the high frequency limit was set by a large notch appearing at around 22 GHz, which was considered to be caused by the excitation of two unwanted modes. In the new system, the jig design was modified to have a back ground plane and vias to suppress these unwanted modes, which resulted in a clean transmission characteristic over the entire frequency range up to 44 GHz. The low frequency limit is determined by the noise figure (NF) of the vector network analyzer input, which was measured to be ∼35 dB in the previous system configuration. The new system employed a low noise amplifier and analog switches to improve the NF to be 2.7 dB below 100 MHz. As a result of these modifications, the operation frequency range of the new TC-Perm system was extended to cover 1 MHz–44 GHz, which is sufficient for characterizing magnetic materials used in noise suppression sheets targeting fifth-generation millimeter-wave (5G mmWave) wireless communication.

49‐4: Novel Composition of Black Bank for OLED

The black colored bank in the back plane of OLED provides not only fine pixels but also high outdoor visibility due to prevention the reflected extraneous light from the lower metal electrode. It has been applied to polarizer‐free panels and commercialized. Lower reflectance of black bank is important for high performance in polarizer‐free panel and many studies are in progress. We present a novel compositional black bank containing a tetraaza porphyrine dye (TAP) with high optical density. The TAP dye shows strong absorption near 550 nm and low reflectance, improving outdoor visibility of display.

CSRR Structure Design for NV Spin Manipulation with Microwave Strength and Fluorescence Collection Synchronous Enhancement.

In this work, we designed, simulated, and tested a complementary split ring resonator (CSRR) for the purpose of applying a strong and uniform microwave field for the manipulation of nitrogen vacancy (NV) ensembles. This structure was fabricated by etching two concentric rings on a flat metal film that was deposited on a printed circuit board. A metal transmission on the back plane was used as the feed line. The fluorescence collection efficiency was improved by about 2.5 times with the CSRR structure compared to that without CSRR. Furthermore, the maximum Rabi frequency could reach 11.3 MHz, and the Rabi frequency variation was smaller than 2.8% in an area of 250 × 75 μm. This could pave the way to achieving high-efficiency control of the quantum state for spin-based sensor applications.

A Miniaturized Dual-Band Short-Ended ZOR Antenna with Backed Ground Plane for Improved Bandwidth and Radiation Efficiency

This paper presents a miniaturized planar dual-band short-ended metamaterial antenna with the backed ground plane to improve antenna bandwidths and radiation characteristics. The proposed dual-band metamaterial (MTM) antenna has been made up of the composite right- or left-handed transmission line (CRLH-TL) concept. Here, the backed ground plane has been employed to generate an extra coupling capacitance (CC), which shifts the ZOR frequency in the lower band while also improving ZOR matching and increasing the impedance bandwidth of the higher-order mode. In this proposed MTM antenna, interdigital capacitance (IDC) has been used in place of a simple series gap, which shifts the higher-order impedance bandwidth into a lower frequency band for second-band Wi-MAX applications (3.3–3.7 GHz). The proposed antenna offers a short-ended MTM, and hence the ZOR frequency is controlled by a series of LC lumped parameters. The proposed antenna offers dual-band behavior with measured −10 dB impedance bandwidths of 5.55% and 41.57% at centered frequencies of 2.70 GHz and 4.33 GHz, respectively. The overall electrical size of the designed antenna is 0.225λ0 × 0.144λ0 × 0.0144λ0 at ZOR (f0 = 2.70 GHz), where λ0 is the free space wavelength; therefore, it is applicable for different Wi-MAX application bands (2.5–2.7 GHz/3.3–3.8 GHz). Furthermore, the proposed dual-band MTM antenna provides compactness, low loss, stable gain, and radiation efficiency, and also offers omnidirectional radiation patterns in the E-plane and dipolar type radiation patterns in the H-plane, respectively.

LAPPD operation using ToFPETv2 PETSYS ASIC

Single photon sensitive detectors used in high energy physics are, in some applications, required to cover areas the size of several m2, and more specifically in very strong demand with an ever finer imaging and timing capability for Cherenkov Ring Imaging Detector (RICH) configurations. We are evaluating the Large Area Picosecond Photo-detector (LAPPD) produced by INCOM company, as a possible candidate for future RICH detector upgrades. In this work we perform tests on the second generation device, which is capacitively coupled to a custom designed anode back plane, consisting of various pixels and strips varying in size, that allows for connecting various readout systems such as standard laboratory equipment, as well as the TOFPET2 ASIC from PETsys company. Our aim is to evaluate what can be achieved by merging currently available technology, in order to find directions for future developments adapted for specific uses.

Wideband Low-Profile Eight-Port Eight-Wave Annular-Ring Patch Antenna Based on Using Eight Dual-Shorted Dual-Resonant Ring Sectors for 8 × 8 MIMO Mobile Devices

A wideband eight-port eight-wave annular-ring (AR) patch antenna for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times $ </tex-math></inline-formula> 8 MIMO mobile devices is presented. The AR patch antenna is formed into eight dual-resonant 45o-ring sectors to radiate eight very-low-correlated or generally uncorrelated waves for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times $ </tex-math></inline-formula> 8 MIMO application. Each ring sector is loaded with two shorting pins and excited by a simple probe feed to generate its half- and quarter-wavelength resonant modes at close frequencies to form a dual-resonant wide operating band. Additionally, all 16 shorting pins of the eight ring sectors have a same distance to the patch center, thereby forming a shorting circle to function like a circular metal wall in the AR patch. This makes the surface currents coupled from the excited ring sector to adjacent sectors to be mainly confined inside the shorting circle. Therefore, with the eight probe feeds located outside the shorting circle in the AR patch, enhanced port isolation is obtained. With the proposed design, the eight-port AR patch antenna having a low profile of 1.4 mm (about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.028\lambda $ </tex-math></inline-formula> at 5.9 GHz) and an outer diameter of 46 mm (about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.91\lambda $ </tex-math></inline-formula> at 5.9 GHz) can generate eight very-low-correlated waves over a wide band of about 5.9-7.2 GHz (fractional bandwidth 20% based on 3:1 VSWR for mobile device application). Also, the proposed antenna has a back ground plane and is especially suitable for on-metal surface application. The use of a single proposed antenna can be conveniently applied for the mobile device or Internet-of-Things (IoT) device to cover such as 5.925-7.125 GHz for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times $ </tex-math></inline-formula> 8 MIMO operation in the possible new mobile communication spectrum.

Wide-band octagon-star fractal microstrip patch antenna for terahertz applications

In this paper, an ultrawideband microstrip patch antenna is proposed for utilizing in terahertz applications. The design consists of three nested octagon-star shaped microstrip patches and an irregular partial ground construction having a rectangular ring resonator with a backing plane. The third iterative unsymmetrical antenna, which is supplied by a modified feedline, has a notch loaded modified ground plane. The antenna operates in impedance bandwidth of 180% (0.6–11.5 THz frequency range) and VSWR ≤ 2.6. The total dimensions of the antenna are 800 × 600 × 81.29 µm. It offers a 16.64 dB peak realized gain and excellent radiation patterns. Wide bandwidth and high peak gain are two benefits of the proposed antenna. The antenna has multiple applications that are introduced in the paper. CST STUDIO Simulator, is used to design and analyze of the proposed antenna.

Security enhancement for adaptive optics aided longitudinal orbital angular momentum multiplexed underwater wireless communications.

The frozen-wave-based longitudinal orbital angular momentum multiplexing (LOAMM) system developed in [IEEE Photonics J.10, 7900416 (2018)10.1109/JPHOT.2017.2778238] has the potential to overcome the crosstalk effects induced by turbulence. In this paper, we propose a defocus measurement aided adaptive optics (DMA-AO) technique for turbulence compensation in a LOAMM underwater wireless optical communication (UWOC) system to investigate the enhancement of physical layer security. Relying on a phase retrieval algorithm and probe beam, three amplitude-only measurements obtained from different back focus planes can realize phase reconstruction of distorted OAM beams. Moreover, the so-called mixture generalized gamma-Johnson SB (GJSB) distribution is proposed to characterize the probability density function (PDF) of reference-channel irradiance of OAM. The GJSB allows for obtaining closed-form and analytically tractable expression for the probability of strictly positive secrecy capacity (SPSC) in a single input single output (SISO) system. Furthermore, the average secrecy capacity (ASC) and probability of SPSC for a multiple input multiple output (MIMO) system are investigated. Compared to the traditional OAM multiplexing system based on Laguerre-Gaussian (LG) beams, the LOAMM system with a probe beam assisted DMA-AO technique has potential advantages for improving the security performance in UWOC.

Characterization of Conductor-Backed Dielectric Substrates Using a Novel Resonance-Based Method

A novel microwave resonance-based method is presented in this paper for complex permittivity characterization of conductor-backed materials. The proposed method constructs a nondestructive technique for extracting complex permittivity proprieties of thin conductor-backed dielectric substrates. The conductor-backed sample is integrated with a planar resonator by employing the conductor backing plane as a grounding surface to the resonance structure. The planar resonator is a finite circular conductive patch hosting a complementary split ring resonator (CSRR). The proposed method exhibits high sensitivity to the conductor-backed material measurements and characterization. Experimental validation of the numerical analysis of the proposed method is provided. Commonly used conductor-backed dielectric substrates with a wide range of relative permittivity values ranging from 2.2 to 10.2 were characterized using the proposed method. Compared to the state of the art material characterization methods using planar resonators, the presented method provides a nondestructive technique for complex permittivity characterization of thin conductor-backed dielectric substrates with high sensitivity to the dielectric properties.

Design of an Ultrawideband Circularly Polarized Printed Crossed-Dipole Antenna Based on Genetic Algorithms for S-Band CubeSat Applications

As in any satellite, onboard antennas for CubeSats are crucial to establish communication with ground stations or other satellites. According to its application, antennas must comply with standardized requirements related to size, bandwidth, operating frequency, polarization, and gain. This paper presents an ultrawideband circularly polarized two-layer crossed-dipole microstrip antenna for S-band CubeSat applications using genetic algorithms optimization tools included in the 3D electromagnetic simulation software Ansys HFSS. The antenna is constructed on a 10 × 10 cm Cuclad-250 substrate with a back copper flat plane, located at λ/4 at 2.25 GHz operating frequency. The backplane with the exact substrate dimensions improves gain and reduces inside satellite radiation. Measured bandwidth defined by S11 at a −10 dB was higher than 1835 MHz with S11 = −24.68 dB at the central frequency of 2.25 GHz, while measured VSWR at the same frequency was 1.124. At 2.25 GHz, the maximum measured gain and the minimum measured axial ratio in the broadside direction were found to be 6 dBi and 0.22 dB, respectively. There are antenna simulations and measurements, as long as its fabrication guarantees application requirements that make it ready for prespace testing.

Transmission Mueller matrix imaging with spatial filtering.

In this Letter, we report a study on the effects of spatial filtering for a transmission Mueller matrix imaging system. A spatial filter (SF) is placed on the back Fourier plane of the imaging lens in a dual-rotating-retarders Mueller matrix imaging system to select photons within a certain scattering angle. The system is then applied to three types of human cancerous tissues. When imaging with a small-aperture SF, some polarimetry basis parameters show sharp changes in contrast in the cancerous regions. Monte Carlo simulations using a simple sphere-cylinder scattering model also show that spatial filtering of the scattered photons provides extra information on the size and shape of the scattering particles. The results indicate that spatial filtering enhances the capability of polarization imaging as a powerful tool for biomedical diagnosis.

P‐13.9: Study of AMOLED Vertical‐Crosstalk mechanism and improvement

The Simulation Model of Back Plane Circuit Vertical Crosstalk (BP‐VC) of AM‐OLED displays was established according to the experimental VC test method in this paper. The impact of the Pixel Storage capacitance (Cst) and the Parasitic Capacitance had been studied. Pixel with good simulated VC had been optimized by increasing Cst and decreasing the parasitic capacitance of gate electrode of driving TFT (N1 node) and Gate line (Cap2), thus reaching the achievement that BP‐VC decreases from 1.54% to 0.76% in 6.5 inch FHD OLED Display.