Arif Mawardi Ismail
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Preferred name
Arif Mawardi Ismail
Official Name
Arif Mawardi, Ismail
Alternative Name
Ismail, Arif Mawardi
Mawardi, A.
Main Affiliation
Scopus Author ID
57224866382
Researcher ID
ABM-8075-2022

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Analysis of an Electrically Induced Optical Waveguide in a c-axis Barium Titanate Thin Film

2021-12-01 , Arif Mawardi Ismail , Prabakaran A/L Poopalan , Nurjuliana Juhari , Mohd. Azarulsani Md. Azidin

In this paper, we report our analysis of an electrically generated optical waveguide in a c-axis barium titanate (BTO) thin film. The waveguide consists of a BTO thin film which is sandwiched between two electrodes. The thin film forms a waveguide when a voltage difference is applied across the electrodes. It is found that the formed waveguide supports both TE and TM modes, with TM modes more tightly confined within the waveguide than TE modes. The possibility to turn the waveguide on and off simply by turning the electric field on and off may prove useful for optical switching.

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Publication

Higher Order OAM Mode Generation Using Wearable Antenna for 5G NR Bands

2023-01-01 , Noor S.K. , Arif Mawardi Ismail , Mohd Najib Mohd Yasin , Mohamed Nasrun Osman , Thennarasan Sabapathy , Shakhirul Mat Salleh , Soh Ping Jack , Rambe A.H. , Ramli N.

This paper presents a flexible and wearable textile array antenna designed to generate Orbital Angular Momentum (OAM) waves with Mode +2 at 3.5 GHz (3.4 to 3.6 GHz) of the sub-6 GHz fifth-generation (5G) New Radio (NR) band. The proposed antenna is based on a uniform circular array of eight microstrip patch antennas on a felt textile substrate. In contrast to previous works involving the use of rigid substrates to generate OAM waves, this work explored the use of flexible substrates to generate OAM waves for the first time. Other than that, the proposed antenna was simulated, analyzed, fabricated, and tested to confirm the generation of OAM Mode +2. With the same design, OAM Mode −2 can be generated readily simply by mirror imaging the feed network. Note that the proposed antenna operated at the desired frequency of 3.5 GHz with an overall bandwidth of 400 MHz in free space. Moreover, mode purity analysis is carried out to verify the generation of OAM Mode +2, and the purity obtained was 41.78% at free space flat condition. Furthermore, the effect of antenna bending on the purity of the generated OAM mode is also investigated. Lastly, the influence of textile properties on OAM modes is examined to assist future researchers in choosing suitable fabrics to design flexible OAM-based antennas. After a comprehensive analysis considering different factors related to wearable applications, this paper demonstrates the feasibility of generating OAM waves using textile antennas. Furthermore, as per the obtained Specific Absorption Rate (SAR), it is found that the proposed antenna is safe to be deployed. The findings of this work have a significant implication for body-centric communications.

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A review of visible-to-UV photon upconversion systems based on triplet–triplet annihilation photon upconversion

2022-12 , Kelvin Voon Yan Jie , Mohd Fairus Ahmad , Muhammad Mahyiddin Ramli , Safizan Shaari , Arif Mawardi Ismail , Yusran Sulaiman

Due to the tunable spectrum range and potential application under non-coherent solar irradiation, triplet-triplet annihilation based molecular photon upconversion (TTA-UC) systems represent a compelling study field for a variety of photonic implementations. There were studies on the incorporation of TTA-UC technology with photovoltaic technology, which made it possible to further improve the energy harvest performance through the utilisation of the wasted spectrum. However, many TTA-UC studies are limited to energy upconversion within the visible spectrum range. For photovoltaic cells with a higher band gap, which harvest the higher energy spectrum (UV region), an efficient Vis-to-UV upconversion is preferred. The Vis-to-UV TTA-UC system was first introduced in 2006. Recently, more studies were conducted to discover the Vis-to-UV upconversion system with high quantum efficiency and low excitation intensity such as the nanocrystal sensitizerbased system and the thermally activated delayed fluorescence sensitizer-based system. Recent studies in the solvent system of Vis-to-UV upconversion system had demonstrated the dependence of the couple photostability on the solvent and extended the solvent selection to inorganic solvent. In this review, we are reviewing the research background of the Vis-to-UV TTA-UC system and discussing the current challenges and potential developments in this research area.

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Analysis of Power Distribution in Mach Zehnder Interferometer Polymer-based Waveguide for Sensing Applications

2022-12-01 , Mohd. Azarulsani Md. Azidin , Nurjuliana Juhari , Arif Mawardi Ismail , Norhayati Sabani

Two Mach Zehnder Interferometer (MZI) polymer-based waveguide designs namely MZI symmetrical and MZI asymmetrical structures were simulated and analyzed using Optiwave OptiBPM10. The two designs with device size of 4000μm x 300μm exhibit clear optical propagation path when light is simulated through them as well as displaying single mode profile. Highest output power was obtained by the MZI symmetrical design at 0.90 a.u, which suggests better waveguide design for sensing applications.

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Investigation on Wearable Antenna under Different Bending Conditions for Wireless Body Area Network (WBAN) Applications

2021-01-01 , Ismahayati Adam , Kamarudin M.R. , Rambe A.H. , Haris N. , Hasliza A Rahim @ Samsuddin , Wan Zuki Azman Wan Muhamad , Arif Mawardi Ismail , Muzammil Jusoh , Mohd Najib Mohd Yasin

This paper analysed the effects of bending on the performance of a textile antenna wherein the antenna under test was made of felt substrate for both industrial, scientific, and medical (ISM) band and WBAN applications at 2.45 GHz. Moreover, the conductive material was used for the patch, and the ground plane used a 0.17 mm Shieldit textile. Meanwhile, the antenna structure was in the form of rectangular, with a line patch in between elements to abate the mutual coupling effect. The measured operating frequency range of the antenna spanned from 2.33 GHz to 2.5 GHz with a gain of 4.7 dBi at 2.45 GHz. In this paper, the antenna robustness was examined by bending the structure on different radii and degrees along both X- and Y-axis. Next, the effects on return loss, bandwidth, isolation, and radiation characteristics were analysed. This paper also discovered that the antenna's performance remained acceptable as it was deformed, and the measured results agreed well with the simulation.

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Design of a 1-Bit Programmable Coding Unit Cell Beamforming Metasurface

2023-01-01 , Johari S. , Amri M.M. , Mohamed Nasrun Osman , Arif Mawardi Ismail , Muzammil Jusoh , Rahim M.K.A.

Traditional phased array antennas rely on costly phase shifters to steer beams by manipulating the phase of induced currents in each antenna element. In this study, we introduce a 1-bit coding metasurface as an alternative to traditional phased array antennas for beam control and modulation of electromagnetic waves. The metasurface operates at 5.8 GHz and consists of digitally controlled unit cells, each incorporating a pin diode. These diodes enable binary coding states of "1" and "0" with a significant 180-degree phase difference. The unit cell, with a dimension of 0.81λ x 0.81λ, comprises two metal patches separated by the pin diode on an FR-4 substrate. Simulation results demonstrate the distinct behavior of the metasurface, with the off-state exhibiting a reflection amplitude response of 1.8dB and the on-state showing a reduced amplitude due to on-resistance. The far-field patterns obtained from the simulations clearly indicate a 90-degree change in the radiation pattern between bit "0" and bit "1." This innovative design offers a cost-effective solution for beam control and versatile electromagnetic wave modulation, making it suitable for various applications, including beamforming in radar and communication systems.

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A Hybrid Mutual Coupling Reduction Technique in a Dual-Band MIMO Textile Antenna for WBAN and 5G Applications

2021-01-01 , Hamza A. Mashagba , Hasliza A Rahim @ Samsuddin , Ismahayati Adam , Jamaluddin M.H. , Mohd Najib Mohd Yasin , Muzammil Jusoh , Thennarasan Sabapathy , Abdulmalek M. , Azremi Abdullah Al-Hadi , Arif Mawardi Ismail , Soh Ping Jack

This paper presents a hybrid mutual coupling reduction technique applied onto a dual-band textile MIMO antenna for wireless body area network and 5G applications. The MIMO antenna consists of two hexagonal patch antennas, each integrated with a split-ring (SR) and a bar slot to operate in dual-band mode at 2.45 GHz and 3.5 GHz. Each patch is dimensioned at 47.2 × 31 mm2. This hybrid technique results in a simple structure, while enabling significant reduction of mutual coupling (MC) between the closely spaced patches (up to 0.1 λ). This technique combines a line patch and a patch rotation technique, explained as follows. First, a line patch is introduced at an optimized distance to enable operation with a broad impedance bandwidth at both target frequencies. One of the patches is then rotated by 90° at an optimized distance, resulting in a significant MC suppression while maintaining the dual and broad impedance bandwidth. The proposed MIMO antenna is further evaluated under several bending configurations to assess its robustness. A satisfactory agreement between simulated and measured results is observed in both planar and bending conditions. Results show that the MIMO antenna achieves an impedance bandwidth of 4.3 % and 6.79 % in the 2.45 GHz and 3.5 GHz band, respectively. Moreover, very low MC (S21 <-30 dB) is achieved, with a low (< 0.002) envelop correlation coefficient, and about 10 dB of diversity gain at both desired frequencies using this technique. Even when bent at an angle of 50° at the x-and y-axes, the antenna bent maintained a realized gain of 1.878 dBi and 4.027 dBi in the lower and upper band, respectively. A robust performance is offered by the antenna against the lossy effects of the human body with good agreements between simulated and measured results.

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Fabrication of Strontium Titanate thin film with pre-crystallized layer via sol-gel spin coating method

2022-12 , Kelvin Voon Yan Jie , Mohd Fairus Ahmad , Muhammad Mahyiddin Ramli , Safizan Shaari , Arif Mawardi Ismail , Yusran Sulaiman

The technique of pre-crystallized layer is introduced in the strontium titanate (STO) thin film fabrication to improve the coating thickness and the crystallinity. The STO thin films were fabricated on glass substrates via the spin coating method with STO precursor solution that was synthesized through the sol-gel process. The characteristics of the thin films were analyzed through X-ray diffraction (XRD) analysis, profilometry, UV-Vis spectra analysis and scanning electron microscopy (SEM) analysis. In the present study, the samples of 20 layers and 25 layers (deposited on the pre-crystallized layer) exhibited better crystallinity as compared with the samples of 5 layers, 10 layers and 15 layers (without the pre-crystallized layer). The samples of 25 layers exhibited the highest film thickness (224 nm), highest absorbance intensity and the highest XRD peak intensity at 32, 40, 47 and 58°, which represent the planes (110), (111), (200) and (210), respectively. The pre-crystallized layer served as the mechanical support for further layer deposition.

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Publication

Analysis of power distribution in mach zehnder interferometer polymer-based waveguide for sensing applications

2022-12 , Mohd. Azarulsani Md. Azidin , Nurjuliana Juhari , Arif Mawardi Ismail , Norhayati Sabani

Two Mach Zehnder Interferometer (MZI) polymer-based waveguide designs namely MZI symmetrical and MZI asymmetrical structures were simulated and analyzed using Optiwave OptiBPM10. The two designs with device size of 4000μm x 300μm exhibit clear optical propagation path when light is simulated through them as well as displaying single mode profile. Highest output power was obtained by the MZI symmetrical design at 0.90 a.u, which suggests better waveguide design for sensing applications.

View
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Publication

Analysis of an electrically induced optical waveguide in a c-axis barium titanate thin film

2021-12 , Arif Mawardi Ismail , Prabakaran A/L Poopalan , Nurjuliana Juhari , Mohd. Azarulsani Md. Azidin

In this paper, we report our analysis of an electrically generated optical waveguide in a 𝑐- axis barium titanate (BTO) thin film. The waveguide consists of a BTO thin film which is sandwiched between two electrodes. The thin film forms a waveguide when a voltage difference is applied across the electrodes. It is found that the formed waveguide supports both TE and TM modes, with TM modes more tightly confined within the waveguide than TE modes. The possibility to turn the waveguide on and off simply by turning the electric field on and off may prove useful for optical switching.

View