Publications
2023
- High Accuracy and Cost-Effective Fiber Optic Liquid Level Sensing System Based on Deep Neural Network
Erfan Dejband, Yibeltal Chanie Manie,Yu-Jie Deng, Mekuanint Agegnehu Bitew, Tan-Hsu Tan, and Peng-Chun Peng
MDPI Sensors, 2023
Abstract: In this paper, a novel liquid level sensing system is proposed to enhance the capacity of the sensing system, as well as reduce the cost and increase the sensing accuracy. The proposed sensing system can monitor the liquid level of several points at the same time in the sensing unit. Additionally, for cost efficiency, the proposed system employs only one sensor at each spot and all the sensors are multiplexed. In multiplexed systems, when changing the liquid level inside the container, the float position is changed and leads to an overlap or cross-talk between two sensors. To solve this overlap problem and to accurately predict the liquid level of each container, we proposed a deep neural network (DNN) approach to properly identify the water level. The performance of the proposed DNN model is evaluated via two different scenarios and the result proves that the proposed DNN model can accurately predict the liquid level of each point. Furthermore, when comparing the DNN model with the conventional machine learning schemes, including random forest (RF) and support vector machines (SVM), the DNN model exhibits the best performance.
2022
- Utilizing a Tunable Delay Line Interferometer to Improve the Sensing Accuracy of an FBG Sensor System
Erfan Dejband, Cheng-Kai Yao, Yibeltal Chanie Manie, Po-Yang Huang, Hao-Kuan Lee, Tan-Hsu Tan, and Peng-Chun Peng
MDPI Photonics, 2022
Abstract: This paper proposes a novel sensing system based on a tunable delay line interferometer. The tunable delay line interferometer has been used to interpret strain, bringing us high accuracy as well as tunability. The shifted wavelength of the fiber Bragg grating (FBG) sensor caused by the applied strain can be visualized by an optical power meter (OPM) instead of an optical spectrum analyzer (OSA) by converting it to a power change using a tunable delay line interferometer (TDI). Different free spectral ranges (FSRs) are assigned to the TDI to investigate the accuracy and operation range of the proposed system. Thus, we achieve high accuracy and sensitivity by adjusting the FSR to 0.47 nm. Experimental results show that the maximum output power variation corresponding to a strain of 10 με is about 0.9 dB when the FSR is set to 0.47 nm. The proposed system is also cost-effective regarding the equipment utilized for interrogation: a tunable delay line interferometer and an optical power meter.
2021
- Prediction of THz Absorption and Inverse Design of Graphene-Based Metasurface Structure Using Deep Learning
Erfan Dejband, Jyun-Wei Li, Peng-Chun Peng, Tan-Hsu Tan
Wireless and Optical Communications Conference (WOCC), 2021
Abstract: This paper presents a new method based on the neural network for predicting the absorption of the THz Graphene-based metasurface structure and inversely designing the structure based on desired absorption spectrum. the absorption spectra have been computed for different values of structure’s parameters. A neural network is trained to predict the absorption of the structure for any random value of the structure parameters with high accuracy and less time-consuming. Moreover, the well-trained neural network can perform the inverse design of the structure based on the desired absorption spectrum. Finally, the performances of various deep learning algorithms are demonstrated.
2018
- Antenna coupled GaN-based pulsed THz emitter array, enhanced with nono-slit plasmonic waveguide modes
Pouya Torkaman, Sara Darbari, Mohammad Javad Mohammad-Zamani, Erfan Dejband, Mohsen Heidari
International Conference on Millimeter-Wave and Terahertz Technologies (MMWaTT), 2018
Abstract: An array of unbiased pulsed GaN-based terahertz emitters based on excitation of different waveguide modes in the metallic contact grating is proposed and simulated for the first time. The proposed emitter consists asymmetric metal semiconductor-metal, so dissimilar Schottky contacts induce internal electric field that accelerates the photogenerated carriers. Furthermore, by taking advantage of plasmonic cavity modes for specific dimensions of the emitter array, it is shown that THz photocurrent can be enhanced about 5 times in comparison with the unbiased emitter array of the same area. We demonstrate that, for appropriate dimensions of the top metal contact in such a THz emitter array, the first order guided modes of the sub-wavelength nano-slit waveguides will be formed between two adjusted metal contacts, which leading to an enhanced optical absorption and the consequent THz photocurrent in the active region. Finally, we have designed a THz antenna with maximum gain of 6.5, and bandwidth of 400 GHz, which is coupled to the proposed THz emitter array to improve the output radiation power.
- Switchable abnormal THz wave reflector based on molybdenum disulfide (MoS2)
Erfan Dejband,Hamidreza Karami,Pouya Torkaman, Manouchehr Hosseini,
International Conference on Millimeter-Wave and Terahertz Technologies (MMWaTT), 2018
Abstract: Recently Controlling the electromagnetic wave, especially in terahertz range is highly demanded due to the development of practical devices and application systems. In this paper, we propose a scheme to design tunable abnormal reflection structure consisting of molybdenum disulfide (MoS 2 ) array on a grounded SiO 2 and a gold layer beneath them to reflect the terahertz wave. In this structure, MoS 2 can be controlled by intrinsic carrier density or voltage bias, to control the electromagnetic reflected beam at terahertz frequency. By adjusting the geometric dimensions of the MoS 2 elements, the reflection phase can cover the range of 0-2π with linear phase shift, thus abrupt phase shifts can be introduced to design the reflected wavefront. Furthermore, the reflective phase gradient over the structure can be switched by controlling the intrinsic carrier density or voltage bias of the MoS 2 , hence reflected beam directions can be switched dynamically. The proposed scheme will bring much freedom in the design of beam manipulation devices and may be applied to terahertz radiation control. Numerical simulations verify the Snell's law generalized at working frequency and far field scattering illustrate the abnormal reflection.
2017
- Tunable electromagnetic interference shield using periodic graphene-based structures in the terahertz regime
Madjid Soltani, Erfan Dejband, Hamidreza Karami, Manouchehr Hosseini
International Conference on Circuits, Devices and Systems (ICCDS), 2017
Abstract: The demand for band broadening in communication devices has caused designing electronic circuits to draw numerous attentions among the research community. Recently, designing and implementation of electronic circuits have been developed in the THz and optical frequencies to achieve ultrafast responses. Thus, electromagnetic interference shields due to its protection effects against disturbances caused by adjacent elements have emerged as a vital issue in THz circuit designing. In this paper, two types of electromagnetic shields are proposed in the THz regime and shielding effectiveness calculated by using transmission line model. Comparisons indicate that the results obtained from the proposed method are in high accordance with those of CST-MWS commercial software..
2016
- Multi resonance perfect absorber based on graphene micro ribbons
Majid Roshanaei, Erfan Dejband Hamidreza Karami, Reza Parvaz
International Conference on Metamaterials, Photonic Crystals and Plasmonics, 2016
Abstract: Metamaterial-based perfect absorbers are used in many applications like photo-detectors, sensors, special light modulators, wireless communications and photovoltaic. The mechanism of absorption is based on the complete suppression of reflection and transmission of incident wave. Here we present a multi resonances perfect absorber made of Graphene micro-ribbons that each ribbons have different values of chemical potential witch brought us tunability, which by changing the value of chemical potential for each ribbon we can change the frequency of resonances independently and we can achieve to a tunable bandwidth. In the following the results for reflection and absorption from simulation are presented. Finally an equivalent circuit model is proposed for our structure and shown to very accurately predict the element absorption.