Multifunctional Logic Devices Research Articles

Tunable perfect absorber and multifunctional logic device based on graphene metamaterial

Both tunable perfect absorber and multifunctional logic device can be accomplished by a novel graphene metamaterial in this paper. The metamaterial utilizes gold as a substrate, covering with a graphene flake and a graphene double-strip-array on dielectric layers. First, the perfect absorption above 99.99% in the terahertz range is achieved depends on the coupling between the two graphene layers. In addition, the tunability is based on the correlation between the conductivity and the Fermi level of graphene. As the Fermi level changes, the absorption peak of the absorber will shift, thus the tunable perfect absorber is accomplished. On this basis, the input Boolean values of the logic function are defined by the Fermi levels of graphene. The output Booleans are distinguished by monitoring the reflections and comparing them with the thresholds. Finally, the multifunctional logic device have been successfully implemented in the terahertz domain. At different frequencies, the logic gates of OR, XNOR and NAND can be realized concurrently. And the NOT logic gate can be obtained synchronously at multiple frequencies. Furthermore, the operational frequencies of the aforementioned four logic functions can be tuned by varying the other Fermi level of graphene. The maximum extinction ratios of OR, XNOR, NAND, and NOT are 13.02 dB, 26.3 dB, 12.06 dB, and 26.3 dB, respectively. This multifunctional metamaterial has potential applications in terahertz optical communication due to its straightforward structure and multiple functions.

Low-Power Negative-Differential-Resistance Device for Sensing the Selective Protein via Supporter Molecule Engineering.

Van der Waals (vdW) heterostructures composed of atomically thin two-dimensional (2D) materials have more potential than conventional metal-oxide semiconductors because of their tunable bandgaps, and sensitivities. The remarkable features of these amazing vdW heterostructures are leading to multi-functional logic devices, atomically thin photodetectors, and negative differential resistance (NDR) Esaki diodes. Here, an atomically thin vdW stacking composed of p-type black arsenic (b-As) and n-type tin disulfide (n-SnS2 ) to build a type-III (broken gap) heterojunction is introduced, leading to a negative differential resistance device. Charge transport through the NDR device is investigated under electrostatic gating to achieve a high peak-to-valley current ratio (PVCR), which improved from 2.8 to 4.6 when the temperature is lowered from 300 to 100K. At various applied-biasing voltages, all conceivable tunneling mechanisms that regulate charge transport are elucidated. Furthermore, the real-time response of the NDR device is investigated at various streptavidin concentrations down to 1pm, operating at a low biasing voltage. Such applications of NDR devices may lead to the development of cutting-edge electrical devices operating at low power that may be employed as biosensors to detect a variety of target DNA (e.g., ct-DNA) and protein (e.g., the spike protein associated with COVID-19).

Theoretical investigation of a multi-functional logic device based on plasmonic Mach-Zehnder interferometer waveguides

Optical logic device is an essential part of the all-optical signal processing system. A multi-functional logic device is proposed in this paper, it consists of plasmonic Mach–Zehnder Interferometer (MZI) waveguides and a couple of identical hexagonal resonators with swiveling ellipses embedded in them. The input boolean value is defined by the rotation angle of rotatable ellipses. The output boolean values are distinguished by monitoring the transmissions of the output port and setting the appropriate thresholds. The finite-difference time-domain (FDTD) method is used to simulate the proposed structure. Ultimately, four logical functions: NOR, AND, OR and NOT could be accomplished simultaneously. Furthermore, the contrast ratios of the four logic gates are obtained by calculating the structure simulated results. Compared with the same type of logic devices, the proposed logic device has better performance in contrast ratio. Therefore, the structure has excellent application prospects in optical communications and photonic integrated devices.

The design and simulation of a multifunctional logic device based on plasmon-induced transparency using two semicircular resonators

A novel optical logic device based on plasmon-induced transparency (PIT) effect is designed. It is composed of two semicircular resonators coupled with the metal–insulator–metal (MIM) waveguide. By monitoring the different wavelengths, six logic operations (AND, OR, NAND, NOR, XOR, and XNOR) can be achieved simultaneously in the proposed structure. The performance of the device is analyzed by temporal coupled-mode theory and finite-difference time-domain (FDTD) method. Moreover, the influence of structure parameters on device performance such as the radius of semicircular resonator, the coupling distance between two semicircular resonators, and the coupling distance between waveguide and semicircular resonator are discussed in detail. The proposed device that can implement six logic operations greatly improves the integration of photonic integrated circuits (PIC), and it has the potential to provide new idea for designing of optical logic device on-chip.

Multimode excitations for complex multifunctional logic device

The simplicity and prospect of energy efficiency of microelectromechanical systems (MEMS) resonator-based computing devices have captivated considerable research interest in recent years. Hence, they are being explored for ultra-low power computing machines, which are currently needed for internet-of-things (IoT) applications. Recently, there have been successful demonstrations of fundamental logic gates. However, the realization of complex multifunctional logic devices that involve multi-input and multi-output lines are facing challenges, such as the interconnections between multiple resonators and the limited controllability of the operating frequency. In this study, we demonstrate a 1:2 Demux combinational logic device with improved energy efficiency using the multi vibration modes of a single MEMS resonator. The MEMS device consists of three connected in-plane microbeams in the form of a U-shape structure. The actuation and modulation are based on electrostatic forces. The device shows actuation energy of 0.082 fJ and 0.91 fJ for output 1 and output 2, respectively, and switching energy per logic operation of 11.01 pJ for output 1 and 5.31 pJ for output 2. This indicates 75% decrease in switching energy per logic operation in comparison with the previously reported values for electrostatically actuated MEMS resonator-based computing devices.

Improving the performance of nanostructure multifunctional graphene plasmonic logic gates utilizing coupled-mode theory

Nanostructure ring resonators are suitable devices for photonic integrated circuits. A nano-scale multifunctional logic device based on plasmon-induced transparency (PIT) is presented here. This device consists of a pair of hexagonal ring resonators coupled with two parallel metal–insulator–metal (MIM) waveguides. According to the coupled-mode theory, the appropriate detuning between the resonances wavelengths of two resonators acts as the key factor to achieve the PIT phenomenon. For this purpose, the PIT phenomenon for several metals utilized in MIM waveguides is studied. Also, graphene has been employed as the replacement for the metal under the hexagonal ring resonator and its parallel waveguides. However, the interaction of light with graphene as a 2D material is weak, by varying the dimensions of waveguides, rings, and their distances, and also, incident light wavelength and graphene chemical potential, we have achieved the desired couplings in the structure. Finite-difference-time-domain (FDTD) simulations confirm that “1” and “0” logic states which represent the high and low levels of the optical power can be achieved at the through and drop ports by changing the refractive index. It has been demonstrated that the proposed structure implements the function of logical operations including XOR and XNOR, simultaneously.

2D-FDTD simulation of ultra-compact multifunctional logic gates with nonlinear photonic crystal

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.

Design of Multichannel Osmium-Based Metalloreceptor for Anions and Cations by Taking Profit from Metal-Ligand Interaction and Construction of Molecular Keypad Lock and Memory Device.

A polypyridylimidazole-based bifunctional Os(II) complex of the type [(bpy)2Os(tpy-Hbzim-dipy)](ClO4)2 (1), where tpy-Hbzim-dipy = 4'-[4-(4,5-dipyridin-2-yl-1H-imidazol-2-yl)-phenyl]-2,2';6',2″-terpyridine and bpy = 2,2'-bipyridine, has been synthesized and structurally characterized for the construction of multifunctional logic devices. After coordination of an [Os(bpy)2](2+) unit to one of the two bidentate chelating sites, the complex offers a terpyridine motif for binding with cationic guests and an imidazole moiety for interacting with selective anionic species. Consequently, the anion- and cation-binding aspects of the metallorecptor were examined in solution and in the solid state by different spectroscopic and electrochemical methods. The complex behaves as a bifunctional sensor for F(-), AcO(-), CN(-), Fe(2+), and Cu(2+) ions in acetonitrile, whereas it is a highly selective chromogenic chemosensor for only CN(-) and Fe(2+) ions in water. Based on various output signals with a particular set of anionic and cationic inputs, the complex mimics the functions of two-input INHIBIT, OR, NOR, and XNOR logic gates, as well as three-input NOR logic behavior. More importantly, the complicated functions of a keypad lock and memory device were also nicely demonstrated by the complex. Finally, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations also provide a rationale for properly understanding and interpreting the experimentally observed results.

Anthraimidazoledione-Terpyridine-Based Optical Chemosensor for Anions and Cations That Works As Molecular Half-Subtractor, Key-Pad Lock, and Memory Device

We designed in this work a new family of anthraquinone and imidazole functionalized bifunctional terpyridine receptor, 2-(4-(2,6-di(pyridine-4-yl)phenyl)-1H-anthra[1,2-d]imidazole-6,11-dione (tpy-HPhImz-Anq) for recognition and sensing of selective anions and cations as well as for the construction of multifunctional logic devices. The terpyridine motif in the receptor was utilized for the cation coordination site and the imidazole moiety as the anion binding site. Both anion and cation recognition aspects of the receptor were thoroughly investigated in acetonitrile, mixed DMSO–water, as well as in solid media via different optical channels such as absorption, steady state, and time-resolved emission spectroscopic techniques. On the basis of the absorption and emission spectral responses toward a specific set of ionic inputs, this unique bifunctional receptor can mimic several advanced logic functions such as those of half-subtractor, key-pad lock, and memory device. We also report the implementation of t...

Proposal for simultaneous all-optical AND, NOR, and XNOR logic gates using QPM cascading nonlinear effects in two PPLNs

We propose AND, NOR, and XNOR logic gates realized simultaneously for 40-Gb/s networks, in which the realization of NOR and XNOR logic gates using only MgO-doped periodically poled lithium niobate (MgO: PPLN) is reported. In our configuration, we exploit broadband quasi-phase matching (QPM) cascaded second harmonic and difference-frequency generation (cSHG/DFG), cascaded sum-frequency and difference-frequency generation (cSFG/DFG) in one MgO:PPLN, and the narrow band QPM sum-frequency generation (SFG) in another MgO:PPLN. The performance, including the quality-factor (Q-factor) and extinction ratio (ER), of the proposed multifunctional logic device is also simulated.

Sensor activity and logic behaviour of PET based dihydroimidazonaphthalimide diester

An ester terminated dihydroimidazonaphthalimide as multi-functional logic device is presented. Due to the optical changes as a function of pH this simple molecule is able to act as a molecular pH metre, a digital comparator and a half-adder. It was demonstrated that the dihydroimidazonaphthalimide comparator could be used as a fundamental element of an optical device for control of pH windows. Also, the ability of the device to detect metal ions in DMF and in water/DMF (3:1, v/v) at different pHs has been evaluated by monitoring the changes of its fluorescence intensity. Among the tested metal ions (Cd2+, Co2+, Cu2+, Fe3+, Ni2+, Pb2+, Zn2+, Bi3+, Hg2+ and Ag+) only Fe3+ and Bi3+ were efficiently detected. In water/DMF (3:1, v/v) XOR and XNOR logic gates are presented using pH and Fe3+ as chemical inputs based on encoding binary digits of logical conventions.

Ultrasmall optical logic gates based on silicon periodic dielectric waveguides

An ultrasmall silicon periodic dielectric waveguides-based multimode interference all-optical logic gate has been proposed. The device consists of three 205 nm wide single-mode input waveguides, a 1.1 μm wide and 5.5 μm long multimode interference waveguide, and three 205 nm wide single-mode output waveguides. The total length and width of the device are 13.7 μm and 3.2 μm, respectively. By changing the states of the input optical signals and/or control signals launched into the device, multifunctional logic functions including OR, NAND, NOR, and NOT gates are performed, and each logic function can be realized at a specific output waveguide in accordance with the launched control signals. The ultrasmall multifunctional logic device has potential applications in high density photonic integrated circuits.