Terahertz reconfigurable single-layer Janus metasurface for directional-asymmetric wavefront manipulation

In this study, we propose complementary metal-oxide−semiconductor (CMOS) NOR logic gates consisting of silicon nanowire (NW) arrays on bendable substrates. A circuit consisting of two p-channel NW field-effect transistors (NWFETs) in series and two n-channel NWFETs in parallel is constructed to operate a two-input CMOS NOR logic gate. The NOR logic gates operate at a low supply voltage of 1 V with a rail-to-rail logic swing and a high voltage gain of approximately −3.0. The exact NOR logic functionality is achieved owing to the superior electrical characteristics of the well-aligned p- and n-NWFETs, which are obtained using conventional Si-based CMOS technology. Moreover, the NOR logic gates exhibit stable characteristics and have good mechanical properties. The proposed bendable NW CMOS NOR logic gates are promising building blocks for future bendable integrated electronics.

100 Gb/s all-optical multifunctional AND, NOR, XOR, OR, XNOR, and NAND logic gates in a single compact scheme based on semiconductor optical amplifiers

In this paper, a novel all-optical NOR logic gate based on two dimension (2-D) photonic crystals (PC) is designed and simulated by a cascade of two all-optical switches. The new all-optical switch is composed of a nonlinear photonic crystal ring resonator (PCRR) and T-type waveguide. The PC structure has a square lattice of silicon rod with refractive index of 3.39 in air. The bandgap of this structure is derived by the plane wave expansion (PWE) method, which is from a/= 0.32 to a/= 0.44. In this structure to work at the wavelength of 1550 nm, the lattice constant ‘a’ should be 630 nm; the total size of the proposed optical NOR gate is only 18 m × 11 m. The simulation results using two dimensional finite difference time domain (FDTD) method indicated that the proposed optical NOR logic gate is a potential candidature for ultrafast optical digital circuits.

Supramolecular porphyrin-fullerene conjugates are employed to build NOR and AND logic gates. A crown ether appended zinc porphyrin and an imidazole or an alkyl ammonium functionalized fullerene are utilized. Quenching of zinc porphyrin fluorescence upon addition of binding-site-selective fullerene inputs forms the design basis of the NOR logic gate, while replacing the fullerene entities from the porphyrin-fullerene conjugate and restoring the original fluorescence by chemical inputs form the design basis of the AND logic gate.

We consider a cylindrical vertical cavity surface-emitting laser with a square-shaped active region, operating with the two Gauss-Hermite modes TEM(10) and TEM(01). Using a rate-equation model that includes the effects of the linewidth enhancement factor, we identify in the parameter space two bistability domains. The two stable states are in one case the doughnut modes and in the other the modes TEM(10) and TEM(01). Focusing on the latter case, we study numerically the conditions for optical switching from one mode to the other on injection of an appropriate control beam, and we demonstrate the possibility of using the laser as a NOR logic gate.

All-optical switching has been theoretically analyzed in LOV2 phototropin, the blue light plant photoreceptor based on nonlinear intensity-induced excited-state absorption. The transmission of a cw probe laser beam at 660 nm through LOV2 protein can be controlled by a cw or pulsed pump laser beam at 442 nm, respectively. This modulation is sensitive to the small-signal absorption coefficient, absorption cross-section of the excited L-state at pump beam wavelength and sample thickness. It is shown that the unique spectral and kinetic properties of wild-type LOV2 and LOV2-C39A mutant, result in the probe beam getting completely switched off (100% modulation), by the pump laser beam of intensity 50 kW/cm² and 1 kW/cm², respectively. The switching response in LOV2-WT is faster (~μs) than in LOV2-C39A mutant (~ms). The results have been used to design an optically-addressed spatial light modulator and all-optical NOT, and the universal NAND and NOR logic gates. The results show the applicability of this novel plant photoreceptor protein for photonic applications.

In this paper, we propose a multilogic gate (MLG) by utilizing a dielectric-loaded graphene-based plasmonic waveguide (DLGPW) in the mid-infrared spectral region. The proposed MLG is composed of DLGPW-based switches and multimode interference (MMI) splitters and supports three logical operations-AND, XNOR, and NOR-simultaneously. First, by proper control of the graphene surface conductivity, a graphene plasmonic on-off switch is presented, and then a 3dB MMI splitter based on a DLGPW for a wavelength of 7.8μm is designed and investigated. Our studies show that electro-optical logic gates based on DLGPWs have not been reported to date. The structure of the presented MLG is very simple and CMOS-compatible. The calculated minimum extinction ratios (ER) for AND, XNOR, and NOR logic gates are 17.53dB, 53.43dB, and 17.53dB, respectively. Also, by some modifications, this structure can act as a NAND logic gate with an ER of 55.22dB. Compact footprint, high ER, and easiness of on-chip implementation are some advantages of the presented MLG.

The novel 2×VDD NOT, NAND, and NOR logic gates have been designed and implemented in a nanoscale CMOS process with only 1×VDD devices. With the proposed dynamic source bias technique, the logic gates can be designed to have 2×VDD tolerant capability. Thus, the new 2×VDD logic gates can be operated under 2×VDD voltage environment without suffering the gate-oxide reliability issue.

A high-performance NOT logic gate (inverter) was constructed by combining two identical metal-insulator-semiconductor field-effect transistors (MISFETs) made on an individual CdS nanobelt (NB). The MISFETs, which used high-κ HfO2 dielectrics as the top-gate insulator layer, show excellent performance, such as low threshold voltage (∼ −0.1 V), a high on/off ratio (∼108), small subthreshold swing (∼65 mV dec−1) and threshold voltage hysteresis (∼30 mV). The supply voltage for the inverter can be as low as 1 V with a voltage gain as high as 14. When the supply voltage is 7 V, the voltage gain is 72, which is the best reported value, as far as we know, for the inverters based on NB/NW n-channel MISFETs. Besides, the inverter can work in a larger input range with highly stable output voltages. Their high output voltages can make full use of the supply voltages, and their low output voltages can be close to zero. NAND and NOR logic gates have been constructed by assembling three such CdS NB MISFETs, which show high performances as well. The operating principle of the inverter is discussed in detail.

Background and Objectives: Universal NOR gate is one of the most important gates in digital design. The all-optical NOR gate can be designed using photonic crystals. These types of gates have a small size and can be integrated.Methods: In this paper, an optical NOR gate is designed based on 2D photonic crystals. A square lattice has been used to design this structure. This logic gate has two main inputs, a bias input and an output. Because the output of the NOR gate must be “1” for zero inputs, a bias input is required. A combination of linear and point defects has also been used to create waveguides. Results: One of the characteristics of this structure is its small size for use in optical integrated circuits. The use of a small number and simple point defects makes the design of this gate easier. The obtained delay time for this gate is 0.06ps. Due to these features, this gate can be used in high-speed optical integrated circuits.Conclusion: In this paper, an all-optical NOR logic gate is designed and simulated using photonic crystals. The use of a small number of point defects has reduced the delay time of this gate. The proposed NOR gate can be used in high-speed optical integrated circuits.

Recently, reconfigurable metasurfaces have facilitated dynamic manipulation of electromagnetic (EM) waves, opening new opportunities for fascinating meta-devices. So far, most devices are working in reflection region with limited polarization states. Here, we demonstrate a reconfigurable multifunctional transmissive metasurface for both linearly and circularly polarized waves manipulations. Specifically, the designed meta-atom contains dual-layer metallic cross-strips and one-layer circular slotted patch. Eight positive-intrinsic-negative diodes are loaded between each strip structure through via hole, with each two of diodes as a group along x- and y-direction, respectively, and thus supporting four switchable states via different applied bias voltages. Numerical results indicate that the designed meta-atom achieves high-rate transmission of 0.9 and individual phase manipulation in four independent transmission channels at 7.4 GHz. As a proof-of-concept demonstration, we numerically and experimentally show different versatile functionalities, including anomalous deflections with steered beams in range of 0° ∼ 40°, orbital angular momentum generation with mode of l = 1, and beam focusing among four polarization-encoded channels at 7.4 GHz. Our metasurface owns the advantages of multi-polarization EM wave manipulations in transmission mode, which completely distinguishes from previously reported works with single polarization in reflection mode.

Multi-level fluorescent logic gate based on polyamine coated carbon dots capable of responding to four stimuli

A detailed theoretical analysis of reverse saturable absorption (RSA) to saturable absorption (SA) transition has been presented in Ru complex [{Ru (bipy)2}2L][PF6], with picosecond laser pulses at 532 nm wavelength. Interestingly, it is shown that an increase in pulse intensity leads to transition from RSA to SA, with increased contrast, due to strong excited-state absorption. Theoretical results are in good agreement with reported experimental results. The effect of pulse intensity, pulse width, frequency and concentration has been studied to optimize the RSA to SA transition, which has been used to design all-optical picosecond NOT, AND, OR, and the universal NAND and NOR logic gates. The designs are the first application of Ru dioxolene complex based all-optical logic gates with picosecond switch off/on time. These results show the potential of transition-metal complexes for photonic applications.

We have synthesized a new molecular switch-based on a macrocycle-clip complex-whose switching behavior not only can be controlled through the use of either K+-[2,2,2]cryptand or NH4+-Et3N systems but also provides color changes that are visible to the naked eye; consequently, this system operates as a two-input NOR functioning molecular logic gate.

We demonstrate a technique to convert p-type single-walled carbon nanotube (SWNT) network transistor into ambipolar transistor by thermally evaporating C60 on top. The addition of C60 was observed to have two effects in enhancing ambipolar characteristics. First, C60 served as an encapsulating layer that enhanced the ambipolar characteristics of SWNTs. Second, C60 itself served as an electron transporting layer that contributed to the n-type conduction. Such a dual effect enables effective conversion of p-type into ambipolar characteristics. We have fabricated inverters using our SWNT/C60 ambipolar transistors with gain as high as 24, along with adaptive NAND and NOR logic gates.