Optical manipulation has been used for the trapping of micrometer-scaled objects, but it is still difficult to control the motion of small molecules on the nanometer scale at room temperature. Plasmonic metal nanostructures are expected to be useful for the optical manipulation of nanoscale molecules using a highly localized electric field. We use the plasmonic Ag nanostructure for a demonstration of optical trapping through the observation using surface-enhanced Raman scattering (SERS) imaging. The optical measurements were conducted under electrochemical potential control to stabilize the nanostructure with target molecules, 4,4′-bipyridyl (44 bpy). Upon increasing the concentration of 44 bpy molecules in an electrolyte solution at room temperature, the blinking frequency of the SERS signal was different in both the spectra and imaging. The dwell time of the SERS signals was increased from several tens of milliseconds to a few seconds, which suggested the successful observation of plasmonic trapping of small molecules through the surface diffusion control. The observed results prove the importance for the control of the surface coverage of the molecules and its influence on surface diffusion under plasmonic molecular trapping.

A numerical approach to calculate the power transfer between nanoscale waveguides was proposed. Series of complex power-transfer simulations have been performed when comparing two adjacent waveguides made of different materials. The results showed interesting focusing phenomena when coupling a waveguide sharing a high power confinement factor to a waveguide sharing a low one. In addition, we describe the physical properties of a nanoscale integrable waveguide for smooth integration in the microelectronics industry and analyze two case studies regarding such a possible integration. It seems that due to the lack of ability to confine the mode inside a nanoscale dimensions waveguide, combining waveguides with current size transistor may be, at this stage, difficult to realize without specific fits of the whole module.

Intersubband transition energy is computed for both core-shell quantum dot (CSQD) and binary capped core-shell quantum dot (CCSQD) of cubic geometry by solving the time-independent Schrodinger equation using the finite difference method. The discretization of the structures in all three spatial directions generates sparse Hamiltonian matrices, which are diagonalized to obtain energy eigenstates for the conduction band. The transition energy for the lowest three energy eigenstates is compared for different structural parameters considering GaAs  /  Al_0.42Ga_0.58As CSQDs. CSQD capped with AlAs (CCSQD) viz GaAs  /  Al_0.42Ga_0.58As  /  AlAs shows higher eigenstates and transition energy, which decreases with the increase in core thickness. Furthermore, the optical properties of these structures have been investigated which are in concurrence with the obtained eigen energy. The broader tuning range and blueshifted higher absorption coefficient of CCSQD support significant application in quantum dot detectors and lasers.

A microscopic nonlinear quantum theory of the interaction of coherent electromagnetic radiation with gapped bilayer graphene is developed. The Liouville-von Neumann equation for the density matrix is solved numerically at the multiphoton excitation regime. The developed theory of interaction of charged carriers with the strong driving wave field is valid near the Dirac points of the Brillouin zone. We consider the harmonic generation process in the nonadiabatic regime of interaction when the Keldysh parameter is of the order of unity. On the basis of numerical solutions, we examine the rates of odd and even high harmonics at the particle–hole annihilation in the field of a strong pump wave of arbitrary polarization. The obtained results show that the gapped bilayer graphene can serve as an effective medium for the generation of even and odd high harmonics in the terahertz and far-infrared domains of frequencies.

A one-dimensional photon crystal structure is proposed to design an omnidirectional broadband reflector. The structural parameters are optimized to reflect complete solar spectrum (0.3 to 2.3  μm) for both TE and TM polarized light. The design analysis is carried out using transfer matrix method. The structure is designed using alternate dielectric–dielectric layers of appropriate refractive indices and layer thicknesses. The proposed structure demonstrates more than 98% reflectivity for the complete wavelength range from 0.3 to 2.3  μm along with 73% emission in 8 to 13  μm, thus showing its potential as a dielectric-based reflector in applications such as daytime passive radiative coolers, and as a heliostat in concentrated solar power.

A conical cross-section gold nanoholes array is fabricated on a multi-mode optical fiber tip with an electron-beam lithography process. Underneath the conical gold nanoholes, nanocavities are etched into the substrate fiber glass to increase the light–matter interaction volume. Localized surface plasmon resonance of the fabricated fiber optical device is characterized by measuring the optical transmittance through the fiber tip in the visible and near infrared spectral range. The fiber optical device is used as an index of refraction sensor to detect isopropyl alcohol, ethanol, and methanol. A largely enhanced sensitivity of 652  nm per refractive index unit due to the conical cross-section gold nanoholes and the nanocavities in the fiber glass substrate is observed. Additionally, the response and recovery times of the fiber-tip plasmon sensor are measured for the first time.

The existing CMOS technology is facing severe challenges to keep up with the complicated needs of nanoscale devices due to several issues such as leakage current at nanoscale levels. Quantum-dot cellular automata has the ability to become an alternative to CMOS technology. In general, adder and subtractor are implemented as a single hardware, at the cost of a small reduction in the speed of addition and subtraction. A dedicated hardware for subtractor will reduce the circuit complexity and increase the speed of the operation. Four different subtractor circuit designs are proposed in quantum-dot cellular automata using different wire crossings and implementation techniques. Wire crossing count is critical in determining the cost of the circuit. The proposed multilayer crossover subtractor circuit has 12% fewer cells, 50% wire crossing reduction, and 10% area reduction compared to the existing design. The proposed rotated cell crossover subtractor circuit has 24% fewer cells, 33% clock phase reduction, 50% wire crossing reduction, and 40% area reduction compared to the existing design. Two clock zone crossover subtractor circuit designs are also proposed with smaller area and crossings. The proposed designs can be stretched to construct different N-bit subtractors. The proposed circuit designs are validated using coherence vector engine in QCADesigner.

Titanate nanotubes were evaluated for photocatalytic depletion of methylene blue (MB) dye under UV radiation in a cylindrical reactor. Titanate has been prepared using the method of hydrothermal treatment where the precursors are TiO₂ and NaOH. Transmitting electron microscopy (TEM) and x-ray diffraction (XRD) were used to characterize the prepared nanotubes. The effect of some parameters was examined. It was shown that removing the dye is effective: dye initial concentration 5 to 10 ppm, dosage of catalyst 0.25 to 0.50 g catalyst/l of the solution, and mixture pH 1.4 to 12.6. A total of 17 runs have been designed to take into account the effective ranges of the effective variables using the experimental Box–Behnken technique. Two polynomial models were tailored to the experimental outputs created by the response surface methodology, demonstrating a functional correlation between MB’s percent degradation and experimental parameters. Design Expert program V.6.0.7 was utilized to maximize the reaction rate of the experimental parameters. The optimum parameter values were initial concentration of MB 5.45 ppm, a dose of TiO₂ 0.50  g  /  l, and pH of the mixture 11.89. Under these conditions, the percentage of degradation of MB was 99.0995%.

Magnetic circular dichroism (MCD) is demonstrated for plasmonic bimetallic nanoparticles. They have an Ag–Au core–shell configuration, which can be synthesized using a seeded growth technique. In the seeded growth process, when the amount of Au (as coating metal) added to the Ag core is small, both ordinary (lower-energy) and extraordinary (higher-energy) modes of localized surface plasmon resonance (LSPR) are detected in optical extinction spectra, suggesting successful formation of well-defined core–shell morphology with a rather thin shell (= AgAu alloy) thickness. Interestingly, the related MCD, showing a typical bisignate magnetoplasmonic response, is more distinct than the extinction signal in the ordinary LSPR mode, but strong damping is found upon thin shell formation. Hence, such bimetallic nanosystems have an advantage of systematic tuning of their magnetoplasmonic behavior, but may not be favorable to obtaining large magneto-optical (MO) activity or MCD amplitudes. The damped MCD response is discussed from a viewpoint of spectral inhomogeneity.

The normalized phase-amplitude representation and the Darboux figure are first defined. Then as an example, we establish the quantum optics description for the field in photonic crystal fibers in the defined representation. The field is evolved from one Darboux state to another state in the Darboux figure. By the continuous inputting (pump) of light, the waves induced by nonlinear effects become stronger (the wave frequency number remains constant at the same distance, and their intensities accumulate). The blueshifted waves induced by the third-order resonant susceptibility are not strong enough to cover other nonlinear effect and turn weak along the length (pump turns weak).

(GaIn)₂O₃ nanostructures are synthesized successfully via chemical vapor deposition without any other reaction or catalyzer material. The morphology and crystal structure are characterized by an energy dispersive spectrometer, scanning electron microscopy, x-ray diffraction (XRD) analytic technologies, and photoluminescence (PL) spectra. With the increasing of temperature, the structure changed from monoclinic to cubic, while the morphology changed from column to spherical. The evolution of the structure and morphology should associate with the variation of the indium content of the (GaIn)₂O₃. The room temperature PL shows a wide emission band, which confirms the cubic and monoclinic structures reveled by XRD. The obtained (GaIn)₂O₃ with different morphologies and structures can offer different choices for applications.

Porosity of semiconductor material has been used for various applications including gas sensing. However, the utilization of such materials for liquid sensing is still unexplored. Keeping this in mind, a highly porous structured film of lead sulphide (PbS) was engineered using a physical vapor deposition process. The fabricated PbS film was characterized for its shape and porosity using SEM, AFM, and Raman spectroscopy. Thus, the prepared PbS film was tested for various analytic aqueous media, such as ethanol, methanol, isopropanol, butanol, acetone, formaldehyde, and water for sensing. It was perceived that the prepared film was selectively responding to ethanol, while no such response was seen for the other analytic aqueous media and water. The prepared film showed a linear response for the detection of ethanol with the sensitivity of ∼0.002 transmission intensity (a.u.) per concentration of water (v/v%) at 1450 nm with a detection limit of 1.1%. Being operated in the short wavelength infrared range, this sensor can find applications in various fields, such as biofuel, medical, and organic chemistry. As compared to refractive index-based sensors which show nonmonotonic behavior with the concentration of water in ethanol, our sensor exhibits monotonic behavior over the whole range.

We synthesized cadmium sulfide (CdS) submicron particles in reverse micelles. We chose the surfactants and the water-to-surfactant molar ratio to influence the formation of reverse micelles such that their average size was 100 nm. The actual size of the particles that we synthesized was consistent with the expected reverse micelle size. The synthesized CdS particles exhibited a strong photoluminescence that comprised an interband emission with a quantum confinement effect and a broad emission that originated from the surface trap states. When combined with the blueshifted absorption edge seen in the submicron particle solution, our prepared submicron particles were an aggregation of semiconductor quantum dots. The submicron-size semiconductor particle is appropriate as an optical trapping target in a variety environments and is beneficial for sophisticated resonant optical manipulation, including enhanced optical trapping force and recoil force manipulation.

We demonstrate continuous and reversible spectral modulation of a photonic crystal cavity resonant mode using electrostatic force. The design and simulation of an H₀ cavity were done using finite-element analysis methods. Fabrication of the sample device was done in a cleanroom using state-of-the-art nanotechnologies that are compatible with fabrication techniques for complementary metal-oxide semiconductors and microelectromechanical systems. Upon the change of the applied bias voltage, the resonant tuning effect is quantitatively demonstrated. Furthermore, the dynamic response of the transmission output intensity with respect to the oscillating applied voltage is demonstrated.

On the basis of Huybrechts’ strong-coupling polaron model, the Tokuda modified linear-combination operator method and the unitary transformation method were used to study the properties of the strong-coupling polaron in a polar slab considering the influence of the Rashba effect, which is caused by the spin–orbit interaction, with the triangular quantum well. Numerical calculation on the KCl, as an example, is performed. The expression for the effective mass(m±*) of the polaron as a function of the slab thickness (d), the velocity (u), and the coupling constant (α) was derived. Numerical results show that the interactions between the orbit and the spin with different directions have different effects on the m±* of the polaron.

We numerically demonstrate ultra-wideband mid-infrared supercontinuum (SC) generation in a liquid-filled arsenic–selenide circular photonic crystal fiber (C-PCF). The inner ring air-holes are filled with two different nonlinear liquids: chloroform (CHCl₃) and carbon disulfide (CS₂). Based on simulation results, we show that ultra-wideband SC spectra spanning from 1 to 20  μm can be achieved using only 5-mm long CHCl₃ liquid filling with a pump optical pulse of 10-kW peak power at the wavelength of 2.55  μm. In addition, using 5-kW peak power, SC spectrum spanning up to 12  μm is obtained in the case of the CS₂ liquid-filled C-PCF.

Quantum-dot cellular automata (QCA) is an evolving technology to design circuits at nanometer levels. Most of the digital systems have an adder integrated in the circuit. Circuits in QCA are implemented using majority gates. Most of the existing adder designs are implemented using majority logic and exclusive-or logic. The circuits in QCA are prone to fabrication defects that can affect the performance of the circuit drastically. Missing cell defect is crucial among them. In this work, the existing gates used to implement the adders are analyzed, and a reliable clock zone full adder is proposed using the better fault tolerant gate. The proposed adder is more reliable since both the Sum and Carry are generated by reliable gates. Missing cell defect analysis and design validation are carried out using QCADesigner. The proposed design has fewer cells and more reliability compared to the designs which have considered reliability as an important factor to design adders.

The generation of high-order harmonics in quasi-one-dimensional graphene nanoribbons (GNRs) initiated by intense coherent radiation is investigated. A microscopic theory describing the extreme nonlinear optical response of GNRs is developed. The closed set of differential equations for the single-particle density matrix at the GNR-strong laser field multiphoton interaction is solved numerically. The obtained solutions indicate the significance of the band gap width and Fermi energy level on the high-order harmonic generation process in GNRs.

Results on alternative processing of CdS_xSe_{1  −  x} nanoparticles, starting from the sequential growth of CdS/CdSe bilayers by a chemical bath deposition technique on soda lime substrate and their subsequent annealing are reported. Different salts, such as cadmium chloride and cadmium nitrate, were used as cadmium precursors to deposit different CdS and CdSe films. The impact of different salts on the formation of the CdS_xSe_{1  −  x} nanoparticles is studied as a function of the S/(S + Se) compositional ratio. The structural, optical, and morphological properties of CdS_xSe_{1  −  x} nanoparticles deposited with S/(S + Se) compositional ratios of 0.06, 0.22, 0.78, and 0.81 were analyzed. The x-ray diffraction, UV–vis, Raman spectroscopy, scanning electron microscope, and EDX techniques were used to characterize CdS_xSe_{1  −  x} nanoparticles. As an important result, it is found that band-gap energy of the ternary phase can be tailored as a function of S/(S + Se) composition.

We designed and studied a narrowband absorber with two absorption peaks for mid-infrared spectroscopy and multispectral detection applications. The absorber is composed of a silicon grating loaded on a continuous gold film. The grating has two silicon strips in each unit cell, with the same height but different widths. Numerical results indicate that the absorption peaks under normal incidence locate at wavelengths of ∼3.863 and ∼4.004  μm, with bandwidths of ∼28 and ∼33  nm, respectively. Both peaks exhibit high absorptivities of >0.996. We found that the excited surface-plasmon-polariton modes traveling in different directions in the structure are spectrally separated and result in the two absorption peaks.

Fano resonances based on circle-with-inner-core and stub structure are investigated using data derived from the finite element method and theoretically explained by the multimode interference coupled mode theory and the electric distribution in the system. The parameters of specific structure are modified to investigate the influence of different parts for this metal–insulator–metal system. Due to the high sensitivity to filled dielectric materials, the proposed structure can be applied as a refractive index sensor, whose performances are also explored. High sensitivity is gained as high as 1183.3  nm  /  RIU. And the figure of merit, a key parameter to describe the sensing characteristic, is achieved as 5.1115  ×  10⁴, which is better than most similar structures. Our work is significant for the sensitive refractive index nanosensor.