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Ahmad Mohebzadeh-Bahabady

Bio: Ahmad Mohebzadeh-Bahabady is an academic researcher from Shahid Rajaee Teacher Training University. The author has contributed to research in topics: Photonic crystal & Logic gate. The author has an hindex of 7, co-authored 18 publications receiving 184 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, a small size, low power, simple and high contrast ratio (CR) structure was designed and simulated to use in photonic crystal-based all-optical logic gates.
Abstract: In this study, a small size, low power, simple and high contrast ratio (CR) structure was designed and simulated to use in photonic crystal-based all-optical logic gates. This structure can be used for both all-optical logic NOT and XOR gates. The suggested structure is composed of three waveguides and a nano-resonator. The nano-resonator was designed by removing two dielectric rods. For use as an optical NOT logic gate, one of the input ports enters the control signal. In this case, the CR between logic levels `0' and `1' is 20.53 dB, which is higher than that of the provided gates based on structures published recently. The CR for the XOR gate is 19.95 dB. The response time to the input signal of the designed gate is 0.466 ps. The simplicity of the structure, small size, and high CR are the advantages of this structure compared to previously provided logic gates. The results have proven a superior prospect for the proposed structure to use in all optical integrated circuits.

74 citations

Journal ArticleDOI
TL;DR: In this paper, an ultra-compact structure is presented for realization of all-optical NOT and XOR logic gates which can be compatible with silicon technology, and the lattice constant and the radius of the rods are selected in such a way in order to operate the logic gates at 1550nm.
Abstract: In this paper, an ultra-compact structure is presented for realization of all-optical NOT and XOR logic gates which can be compatible with silicon technology. Logic gates are based on two-dimensional photonic crystals, and the lattice constant and the radius of the rods are selected in such a way in order to operate the logic gates at 1550 nm. The proposed structure consists of three waveguides which are connected to each other using a T-shaped junction. This structure is optimized by two nano-resonators and has also two input ports and one output port. For our numerical studies, the plane-wave expansion and finite-difference time-domain methods have been used. The contrast ratios for the proposed all optical NOT and XOR logic gates are respectively 43.40 and 43.38 dB. The response time of the logic gates is 0.37 ps, which in turn creates a data transmission rate of 3.15 Tb/s. Our studies have shown that the NOT-designed logic gate is suitable for the use in optical integrated circuits.

54 citations

Journal ArticleDOI
TL;DR: Using a two-dimensional photonic crystal lattice, a compact and simple structure has been introduced in the present study to construct an all-optical half adder, which operates under the interference effect as discussed by the authors.
Abstract: Using a two-dimensional photonic crystal lattice, a compact and simple structure has been introduced in the present study to construct an all-optical half adder. The designed structure operates under the interference effect. The phase difference has been created in different states by putting the point defects and the difference in the length of the input waveguides. To do analyses, the finite-difference time-domain method and the plane wave expansion have been used. The advantages of this design include the small dimensions, high possibility of construction, compatibility with the silicon-based technology, and equality of the output power in the logic states 0 and 1. The contrast ratio calculated for the port Sum and the port Carry has been equal to 9.3 and 8.22 dB. The response time has been equal to 0.22 ps, generating the data transfer rate of 4.55 Tbps.

39 citations

Journal ArticleDOI
TL;DR: In this article, a two-dimensional finite-difference time-domain method and plane-wave expansion approach are applied to analyze a photonic crystal nano-ring resonator.
Abstract: In this paper, a biosensor is designed and optimized based on photonic crystal nano-ring resonator. The ring resonator is formed by two consecutive curves and is sandwiched by two waveguides. For analyzing this biosensor, two-dimensional finite-difference time-domain method and plane-wave expansion approach are applied. Sensing mechanism of the biosensor is based on the intensity variation scheme. When the sensing hole has different refractive indices, output transmission spectrum is shifted. Intensity variations occurred at the wavelength of 1,482.7 nm. The results show that in this biosensor for a unit change in the refractive index, intensity of the transmission spectrum is reduced by 14.26 units.

37 citations

Journal ArticleDOI
TL;DR: In this article, a nano-ring resonator-based demultiplexer was proposed, in which scattering rods are used at the corners of the structure to achieve low channel spacing and high quality factor.
Abstract: In this paper, we first present the design of a nano-ring resonator-based filter, in which scattering rods are used at the corners of the structure. By choosing a suitable radius for the dielectric rods in the nano-ring resonator, low channel spacing and high-quality factor parameters have been achieved at 1586.8 nm wavelength. Then, using this filter, a 2-channel demultiplexer is developed. In the proposed demultiplexer, two lattice constants are used: a1 for the main structure and a2 for the structure in the nano-ring resonator. The difference in the lattice constants results in an increase in the quality factor. Some of the advantages of this 2-channel demultiplexer include an average quality factor of 5443, average channel spacing of 0.35 nm, and central wavelengths of 1554.5 nm and 1557.1 nm, respectively, for the first and second channels. Moreover, the minimum and maximum inter-channel cross talks are − 17.63 dB and − 12.1 dB, respectively. Due to the 2.6 nm inter-channels spacing, this structure can be exploited in optical integrated circuits, WDM and DWDM systems.

24 citations


Cited by
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Journal ArticleDOI
TL;DR: A two-dimensional photonic crystal ring resonator based sensor is proposed and designed to detect the glucose concentration in urine over the range of 0 gm/dl-15 gm /dl and can predict the result very accurately without any delay, hence, this attempt could be implemented for medical applications.
Abstract: Photonic sensing technology is a new and accurate measurement technology for bio-sensing applications. In this paper, a two-dimensional photonic crystal ring resonator based sensor is proposed and designed to detect the glucose concentration in urine over the range of 0 gm/dl-15 gm/dl. The proposed sensor is consisted of two inverted “L” waveguides and a ring resonator. If the glucose concentration in urine is varied, the refractive index of the urine is varied, which in turn the output response of sensor will be varied. By having the aforementioned principle, the glucose concentration in urine, glucose concentration in blood, albumin, urea, and bilirubin concentration in urine are predicted. The size of the proposed sensor is about 11.4 µm×11.4 µm, and the sensor can predict the result very accurately without any delay, hence, this attempt could be implemented for medical applications.

74 citations

Journal ArticleDOI
TL;DR: In this paper, a small size, low power, simple and high contrast ratio (CR) structure was designed and simulated to use in photonic crystal-based all-optical logic gates.
Abstract: In this study, a small size, low power, simple and high contrast ratio (CR) structure was designed and simulated to use in photonic crystal-based all-optical logic gates. This structure can be used for both all-optical logic NOT and XOR gates. The suggested structure is composed of three waveguides and a nano-resonator. The nano-resonator was designed by removing two dielectric rods. For use as an optical NOT logic gate, one of the input ports enters the control signal. In this case, the CR between logic levels `0' and `1' is 20.53 dB, which is higher than that of the provided gates based on structures published recently. The CR for the XOR gate is 19.95 dB. The response time to the input signal of the designed gate is 0.466 ps. The simplicity of the structure, small size, and high CR are the advantages of this structure compared to previously provided logic gates. The results have proven a superior prospect for the proposed structure to use in all optical integrated circuits.

74 citations

Journal ArticleDOI
TL;DR: In this paper, a photonic crystal ring resonator based bio sensor is designed to sense different blood constituents in blood in the wavelength range of 1530 nm to 1615 nm for biomedical applications.
Abstract: In this paper, a photonic crystal ring resonator based bio sensor is designed to sense different blood constituents in blood in the wavelength range of 1530 nm‒1615 nm for biomedical applications. The blood constituents such as hemoglobin white blood cell, red blood cell, blood sugar, blood urea, albumin, serum bilirubin direct, and ammonia are sensed for the corresponding transmission output power, Q factor, and refractive index changes. As the blood constituent has unique refractive index, the resonant wavelength and output power are varied from one to another, which are used to identify the blood constituents.

71 citations

Journal ArticleDOI
TL;DR: In this article, the authors examine various types of photonic crystal sensors, such as waveguides, nanoresonators, LX resonators, holes, multi-channel resonators and fibers.
Abstract: Photonic crystals are nanoscale structures that affect the motion of photons. The strong light limitation in photonic crystals and the adjustment of its structural parameters have led to the emergence of photonic crystal biosensors. Moreover, the use of holes as a feature of photonic crystals has resulted in sensors that are very sensitive to low refractive index changes with a small sensing area, which offers flexibility and integration on single-chip systems. Using emerging optofluidic technology, label-free biosensors are on the rise. In this review, we examine various types of photonic crystal sensors, such as waveguides, nanoresonators, LX resonators, holes, multi-channel resonators, nano RINGS resonators, and fibers. These sensors are based on the measurement of biomolecules and the refractive index properties that have been identified. Finally, a variety of challenges and guidelines for the construction of label-free diagnostic biosensors are examined.

61 citations

Journal ArticleDOI
TL;DR: In this article, an ultra-compact AlGaAsκ(3) photonic crystal structure to realize multifunctional logic responses is reported, and the properties of the proposed model are numerically investigated with different physical parameters by the 2D-finite difference time domain (FDTD).
Abstract: In the present paper, we aim to report an ultra-compact AlGaAsκ(3) photonic crystal structure to realize multifunctional logic responses. The properties of the proposed model are numerically investigated with different physical parameters by the 2D-finite difference time domain (FDTD) method. For this purpose, the effect of the geometrical parameters and dielectric materials, including Si and InSb, in the near-infrared region are studied. To obtain dynamical tunability of the proposed model, the effect of the defects is then utilized. Numerical results show that the proposed devices are able to operate as multifunctional logic devices including an AND gate and a demultiplexer. Moreover, the structure has a compact footprint of 8.85 μm×8.85 μm×100 nm. We expect that this theoretical result leads to remarkable applications in photonic integrated circuits, e.g., optical memory.

56 citations