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A three-dimensional fluid model for surface-wave plasma (SWP), to investigate the discharge characteristics of a rectangular SWP source working in a steady state, was presented. The simulation is performed for different gas pressures in argon and different deposited powers. The results showed that there is a peak of plasma density at a distance of 2 cm to 3 cm from the plasma-quartz interface whose position depends mainly on the gas pressure but not the deposited power. The spatial distributions of plasma parameters and their dependence on the gas pressure and deposited power are also presented and discussed. Using this model a good agreement between the simulation results and the available experimental data is obtained.

The principle of surface wave plasma discharge in a rectangular cavity is introduced simply based on surface plasmon polariton theory. The distribution of surface-wave electric field at the interface of the plasma-dielectric slab is investigated by using the three-dimensional finite-difference time-domain method (3D-FDTD) with different slot-antenna structures. And the experimental image of discharge with a novel slot antenna array and the simulation of the electric field with this slot antenna array are both displayed. Combined with the distribution of surface wave excitation and experimental results, the numerical simulation performed by using 3D-FDTD is shown to be a useful tool in the computer-aided antenna design for large area planar-type surface-wave plasma sources.

A self-consistent and three-dimensional (3D) model of argon discharge in a large-scale rectangular surface-wave plasma (SWP) source is presented in this paper, which is based on the finite-difference time-domain (FDTD) approximation to Maxwell's equations self-consistently coupled with a fluid model for plasma evolution. The discharge characteristics at an input microwave power of 1200 W and a filling gas pressure of 50 Pa in the SWP source are analyzed. The simulation shows the time evolution of deposited power density at different stages, and the 3D distributions of electron density and temperature in the chamber at steady state. In addition, the results show that there is a peak of plasma density approximately at a vertical distance of 3 cm from the quartz window.

A three-dimensional model of a surface-wave plasma (SWP) source is built numerically using the finite-difference time-domain (FDTD) method to investigate the structure of the surface wave propagation along the plasma-dielectric interface and the distributions of electromagnetic fields in the whole system. A good-performance excitation source technique for the waveguide which is pivotal to the simulation is presented. The technique can avoid the dc distortions of magnetic fields caused by the forcing electric wall. An example of simulation is given to confirm the existence of the surface waves. The simulation also shows that the code developed is a useful tool in the computer-aided design of the antenna of the SWP source.

The principle of surface wave plasma discharge in a rectangular cavity is introduced and the distribution of the electromagnetic field within a rectangular waveguide is analysed. A novel structure of a slot antenna array is presented. In comparison with the traditional slotantenna, it is shown that the designed slot antenna array can excite effectively the surface wave coupling into the chamber, and generate a stable large-area high-density plasma. These results are useful for exploring the optimized design of the slot-antenna for surface wave plasmas.

Gold nanorods with different aspect ratios are prepared in micells using a seeded growth method. Their extinction spectra are observed with an UV–visible spectrophotometer and analysed theoretically. It is known that there are two plasmon resonance peaks for gold nanorod corresponding to transverse and longitudinal plasmon resonance respectively. Moreover, the longitudinal plasmon resonance peak shifts to long wavelength when we increase the aspect ratio determined from TEM. Especially, we model the extinction spectrum using Gans' theory and compare it with our experimental result. Considering the aspect radios distribution of gold nanorods, it is found that longitudinal plasmon resonance peak will be wider than the nanorods with single aspect ratio, which is consistent with our experimental result. In addition, the effect of dielectric constant of surrounding medium is considered.

The propagating behaviours, i.e. phase shift, transmissivity, reflectivity and absorptivity, of an electromagnetic (EM) wave in a two-dimensional atmospheric pressure plasma layer are described by the numerical solutions of integral-differential Maxwell's equations through a generalized finite-difference-time-domain (FDTD) algorithm. These propagating behaviours are found to be strongly affected by five factors: two EM wave characteristics relevant to the oblique incident and three dimensionless factors. The two EM wave factors are the polarization mode (TM mode or TE mode) and its incident angle. The three dimensionless factors are: the ratio of the maximum electron density to the critical density n0/ncr, the ratio of the plasma layer width to the wave length d/λ, and the ratio of the collision frequency between electrons and neutrals to the incident wave frequency ve0/f.

We theoretically analyse the temperature effects on a surface plasmon resonance (SPR) sensor in Kretschmann configuration. The temperature effects include the thermo-optic effect and the dispersion of thermal-optic coefficient in the dielectric along with the thermal expansion effect, phonon–electron scattering and electron–electron scattering in the metal layer. We simulate the temperature dependence of the resonance position and the sensitivity of the SPR sensor under wavelength-interrogation and angular-interrogation mode of operation and the differences are pointed out in the two modes.

When a small metallic nanoparticle is irradiated by incident light, the oscillating electric field can cause the conduction electrons to oscillate coherently, which excites the local surface plasmons (LSPs). As is well known, excited LSPs can gather the energy of incident light to the surface of metallic nanoparticle. Recently, some nonspherical particles, e.g. tetrahedron, are suggested to obtain stronger localized electric field. We employ the discrete dipole approximation method to calculate the optical response of the tetrahedron nanoparticle, including the extinction and distribution of the electric field around the particle. The influences of some parameters, including the nanoparticle size, incident direction and polarization, are investigated to analyse the response modes and to obtain stronger localized electric field.

Surface plasmons (SPs) associated optical single-pass effect has been investigated in novel subwavelength metallic structures, including single slit and grating structures. With influence of SPs, these metallic structures can enhance transmission in incident direction and suppress it in the opposite direction, exhibiting a single-pass effect. The finite difference time domain method is employed to study the influences of structure parameters on far-field transmission, near-field electric field distribution and extinction ratio of the single-pass transmission effect. A maximal extinction ratio of 47.83 dB is achieved in the grating structure.

Planar polymer multi-model waveguides doped with Ag nano-particles and rhodamine B are fabricated and investigated by the spectroscopy analysis method as well as the M-line method. Experimental results shown that fluorescence enhancement occurs when excited by a wide band wavelength with Ag nano-particle concentration at a certain level. The maximum enhancement factor in our experiment is obtained to be about 3.8 when excited by 350 nm. Our study may have potential applications in polymers optical elements, such as polymer waveguide lasers and amplifiers.

We study the fundamental problem of reflection and refraction of a surface polariton as it strikes the interface between two waveguide structures. By making the two waveguide structures match to each other, coupling of surface polaritons to radiating modes is cancelled, and the reflected and transmitted waves consist of only surface modes. The reflection and transmission coefficients are calculated, and negative refraction of surface polaritons is demonstrated. Finite-difference time-domain numerical simulations are also performed to verify the analytical results. As one of the applications of the matched waveguide structure, a square corner reflector for phase-retardation-free reflection of surface polaritons is proposed.

The boundary diffraction wave theory is introduced to analyse a near-field diffraction (NFD) pattern of a metallic probe tip of apertureless scanning near-field microscopy. This method is simple and can give a clear physical picture. The polarization effect of the incident light and the different shapes of the metallic probe tip are simulated. The results show that the NFD pattern of the metallic probe tip is directly related to those factors.

We report on a novel organic chromophore with symmetric twisted intramolecular charge transfer (TICT) state on excitation. The properties of nonlinear transmission induced by three-photon absorption (3 PA) are demonstrated pumped with nanosecond laser pulse. Large 3 PA cross sections as high as the order of 10−74 cm6s2 have been obtained for nanosecond and picosecond laser pulses at 1064 nm from intensity-dependent transmission measurements. Similar two emissive behaviours from one-photon and three-photon excited fluorescence spectra indicate that the linear and nonlinear fluorescences share the same TICT relaxation process from the excited states. The intensity dependence of upconversion fluorescence on the incident intensity obeys the cubic law that characterizes the three-photon absorption.

In this paper, a new Y-shaped beam splitter is designed by combining the partial band gap with self-collimation in a two-dimensional photonic crystal, and the design has been validated by finite-difference time-domain simulation. Simultaneously, we improve the design and enhance the power transmission ratio by inserting an air trench into the incident waveguide. The transmission rises from 24% to 44% at the normalized frequency of 0.185 in each branch, and the maximum transmission ratio within the frequency range of self-collimation reaches 47% at the normalized frequency of 0.187.

A design of a polarization beam splitter (PBS) in two-dimensional triangular photonic crystals is proposed and numerically demonstrated, for the first time to our knowledge. The principle of the model is based on the polarization dependence of the photonic band gaps in photonic crystals; the polarization extinction ratios for transverse-magnetic and transverse-electric modes are 11.5 dB and 46.7 dB at the centre of its operating frequency range, respectively. When the central wavelength is tuned at 1550 nm, the possible operation wavelength range of this structure can be as large as 28.5 nm, which almost covers the whole C band in modern optical communication systems. Furthermore, due to its small size and only one kind of material being involved, the PBS structure may have practical applications in the integrated optics field.

We investigate optical absorption and emission spectra of Sm 3+ ions in Sm(DBM)3Phen-doped polymethyl methacrylate (PMMA). Based on the Judd–Ofelt theory, the optical intensity parameters are calculated to be Ω2 = 13.76×10−20 cm2, Ω4 = 3.41×10−20 cm2, Ω6 = 4.01×10−20 cm2 from the absorption spectrum of Sm(DBM)3Phen-doped polymethyl methacrylate. The optical intensity parameters have been used to calculate the total radiative transition rate (676.57 s −1 ) and radiative lifetime (1478 μs) of the 4 G 5/2 exciting state. The stimulated emission cross-sections σ ij and the fluorescence branch ratios for the 4 G 5/2→6 F J' and 4 G 5/2→6 H J' transitions are also evaluated. The analysis reveals that Sm(DBM)3Phen-doped PMMA is promising for applications in rare-earth-doped polymer devices.

The birefringence grating and the surface grating in azobenzene polymer liquid-crystal (Azo-PLC) films are studied by a near-field scanning optical microscope. With laser irradiation, the refractive index change caused by birefringence and the sinusoidal surface profile are observed at the near-field transmittance image and the surface topography of the grating. The grating period and the peak-to-peak value of the sinusoidal surface profile are 0.8 µm and 40 nm, respectively. The maximum diffractive efficiency of the grating is 2%. The dynamic process of the grating formation is probed and analysed. The mass diffusion responsible for the formation of the surface grating due to the temperature rise is analysed.

In this paper, the triple differential cross section for the low-energy electron impact ionization of the Li+ ion is considered in the coplanar equal energy-sharing kinematics at an incident energy of 114.083 eV. The emergence of structures in the calculated cross sections is explained in terms of isolated two-body final-state interactions and three-body coupling. The cross section shows two peaks originating from `classical' sequential two-body collisions. The position of these peaks is determined by two-body final-state interactions. In addition, it is demonstrated that the signature of three-body interactions is carried by the magnitude and ratio of these two peaks. The direct and exchange amplitudes are also considered.

Raman spectra from polymethyl methacrylate (PMMA) core polymer optical fibres (POFs) in the 200–6800 cm−1 range were investigated using an Ar+ ion laser. Raman peak shifting and Raman spectra broadening were observed and analysed in the POFs. Polarized laser-induced birefringence in an azobenzene-doped PMMA fibre material was investigated. We found both a fast response mode and a slow response mode in the rise and decay process of the laser-induced birefringence. It is demonstrated that the characteristics of polarized laser-induced birefringence were strongly dependent on the pump laser power.

Some nonlinear behavior in electron cyclotron resonance plasma was investigated using a two-dimension hybrid-mode with self-consistent microwave absorption. The saturation, oscillations of plasma parameters (plasma density, potential, electron temperature) versus operating conditions (pressure, power) are discussed. Our simulation results are consistent qualitatively with many experimental measurements.

An estimation method of plasma density based on surface plasmons theory for surface-wave plasmas is proposed. The number of standing-wave is obtained directly from the discharge image, and the propagation constant is calculated with the trim size of the apparatus in this method, then plasma density can be determined with the value of 9.1 × 1017 m−3. Plasma density is measured using a Langmuir probe, the value is 8.1 × 1017 m−3 which is very close to the predicted value of surface plasmons theory. Numerical simulation is used to check the number of standing-wave by the finite-difference time-domain (FDTD) method also. All results are compatible both of theoretical analysis and experimental measurement.

A photonic crystal fibre (PCF) surface enhanced Raman scattering (SERS) sensor is developed based on silver nanoparticle colloid. Analyte solution and silver nanoparticles are injected into the air holes of PCF by a simple modified syringe to overcome mass-transport constraints, allowing more silver nanoparticles involved in SERS activity. This sensor offers significant benefit over the conventional SERS sensor with high flexibility, easy manufacture. We demonstrate the detection of 4-mercaptobenzoic acid (4-MBA) molecules with the injecting way and the common dipping measurement. The injecting way shows obviously better results than the dipping one. Theoretical analysis indicates that this PCF SERS substrate offers enhancement of about 7 orders of magnitude in SERS active area.

We demonstrate active manipulating plasmonic signals with metal-nonlinear optical material–metal (M-NL-M) arrays consisting of slits with variant widths. The parameters of the M-NL-M array structure are derived by theoretical analysis of dispersion relationship. The splitting angle can be modulated by the incident light intensity, and verified by a nonlinear two-dimensional finite difference time domain method. The physical principle of this phenomenon is analysed from the phase of surface plasmon polaritons and Fabry–Perot (F-P) resonance in slits.

We re-examine the classical one-dimensional transmission grating to explain the enhanced transmission in the surface impedance approximation. The nearly zero transmission and extraordinary transmission phenomena related to the surface plasmon are presented by analysing the scattering amplitude of waveguide mode at the output surface of grating. It is revealed that the transmission peaks are related to the Fabry–Perot factor and the interaction of surface plasmon and other diffractive orders.

Sub-diffraction-limit imaging in the optical hyperlens based on cylindrical metamaterials is studied. Some parameters of hyperlens, such as the dispersive relation and the divergence angle of imaging, are numerically analysed with the ray trajectory method and effective medium theory. The dependence of imaging properties on dielectric constant is discussed. As a result, a 0° divergence angle is obtained for the best imaging effect. This work will be helpful for the design, structure fabrication and resolution improvement of the optical hyperlens.

Influence of hyperlens structure parameters, such as curvature radius and layer number, and incident wavelength on the beam propagation is numerically investigated by FDTD. It is found that the intensity and the full width at half maximum (FWHM) of the output beam can be controlled by the structure parameters and operating wavelength. The optimized structure parameters and operating wavelength are obtained, which will be of great significance in design and fabrication of optical hyperlens with high resolution.

We report a novel single-frequency fibre ring laser using self-injection locking with a distributed-feedback (DFB) fibre laser at 1550 nm. The operating wavelength is controlled by a saturable absorber and a DFB fibre laser in the ring cavity the saturable absorber acts as a narrow band-pass filter. In the primary experiment, the laser output exceeds 100mW with the linewidth less than 2kHz. The laser is stable, and no mode-hopping is observed within eight hours. Compared with other cavity designs using spatial hole-burning, our laser shows high controllability.

Conventional all-optical switches based on azo polymer films and the all-optical switches based on the attenuated total reflection (ATR) geometry are investigated. A conventional switch system, including a pump beam of 532 nm and a probe beam of 650 nm, is based on the photoinduced birefringence effect of azo polymer. An ATR switch in a prism-multilayer configuration is achieved by changing the reflectance of the probe beam with an external pump beam. The ATR method provides the substantial improvement of the speed and the efficiency of the modulation over the conventional method. Although the azo polymer response still remains relatively slow, an enhanced nonlinear refractive index of the azo polymer film can effectively increase the modulation.

Based on the rigorous coupled-wave analysis algorithm, we have systematically analysed the effect of the geometrical parameters of a dielectric film coated metallic grating with subwavelength slits on extraordinary optical transmission for s-polarization illumination. Results show that the dielectric film which sustains a waveguide electromagnetic mode on the top of the metallic lamellar grating can strongly enhance the transmittance, the positions of the transmission peaks are mainly determined by the period of the metallic grating, the thickness and refractive index of the dielectric film. This structure shows potential applications in excellent polarizers or polarization-isotropic devices at infrared spectral range by appropriately choosing the geometrical parameters.

We report the observation of rectangular shape spectrum in passively mode-locked fibre laser with positive dispersion cavity. The spectrum is broad and flat, and 3 dB bandwidth can be up to 17.61 nm. Multiple-pulse operation is observed in our laser system. The spectrum width, pulse energy, pulse width and peak power of the mode-locked laser output change with the appearance of multiple-pulse operation.

The composite PMMA films containing Ag nanoparticles and rhodamine 6G are prepared. We investigate the fluorescence properties and nonlinear optical properties of R6G/PMMA films influenced by Ag nanoparticles. The fluorescence enhancement factor is about 3.3. The corresponding nonlinear refractive index is measured to be −2.423×10−8 esu using the Z-scan technique, which is much enhanced compared with the R6G/PMMA film. The results indicate that these enhancements are attributed to surface plasmon resonance of Ag nanoparticles.

When an electromagnetic (EM) wave propagates in an atmospheric pressure plasma (APP) layer, its attenuation depends on the APP parameters such as the layer width, the electron density and its profile and collision frequency between electrons and neutrals. This paper proposes that a combined parameter—the product of the line average electron density and width d of the APP layer (i.e., the total number of electrons in a unit volume along the wave propagation path) can play a more explicit and decisive role in the wave attenuation than any of the above individual parameters does. The attenuation of the EM wave via the product of and d with various collision frequencies between electrons and neutrals is presented.

The finite-difference-time-domain (FDTD) method is applied to simulate the two-dimensional propagation of electromagnetic TM (S-polarization) mode in atmospheric plasma and in metal layer for strong electron-neutral collisions. Dependence of the wave attenuation on both plasma parameters and incident wave angle are obtained. It is indicated that for a given electron density profile the attenuation depends strongly on the incident angle, the wave frequency, the width of plasma layer, and the collision frequency between electrons and neutrals.

The finite-difference-time-domain method is applied to simulate the two-dimensional propagation of a p-polarization mode electromagnetic wave in atmospheric plasma and metal layer for strong electron–neutral collisions. It is indicated that for a giving electron density profile, the p-polarization attenuation is very different from the s-polarization attenuation and it depends even strongly on the incident angle. The mechanism of p-polarization attenuation is analysed by the interference of wave and the relationship between the attenuation property and the main parameters is given.

The propagation property of an electromagnetic wave in a thin plasma layer at high pressure is investigated with the finite-difference time-domain method. The effects of the non-uniformity of plasma distribution, and the frequency of incident wave on the propagation property of the electromagnetic wave are discussed. Numerical results indicate that the phase shift and the reflectivity of wave are sensitive to plasma density distribution, and reflectivity is lower at the middle band of frequency for different plasma distributions.

We present a new concept of the microfluidic super-resolution near-field structure (MSRENS) based on a microfluidic structure and a super-resolution near-field structure. The near-field distance control, ``nano-probe'' and scanning can be realized simultaneously using the MSRENS, which is similar to a near-field scanning optical microscope. The design and simulation results are presented. Numerical simulation has demonstrated that the MSRENS with spatial resolution beyond the diffraction limit could be applicable in chemistry, biologics, and many other fields.

We present a new laser Doppler velocimetry based on self-mixing effect using a single longitudinal-mode vertical-cavity surface-emitting laser modulated by a dynamic triangular current. It can indicate the direction of velocity without ambiguity in a wide dynamic range of 5.2–479.9 mm/s. The accuracy of velocity measurement is better than 3.1% in the whole velocity range when a diffusing target is used for measurements. More interestingly, it works very well on different diffusing surfaces, even on a black glossy photographic paper.

A step-index polymer optical fibre (SI POF) containing rhodamine B in poly (methyl methacrylate) (PMMA) has been fabricated by a perform technique. The rhodamine B content of the doped SI POF is 5 ppm-wt. The spectra of the doped SI POF with different fibre lengths were measured. Amplified spontaneous emission (ASE) at 609 nm of an SI POF in length 40 cm has been observed at ambient temperature by end-pumping with a Nd:YAG laser operated at 532 nm. The threshold of absorbed pump power for the onset of ASE is about 0.003 mJ.

This paper shows the evolution of density and temperature of multi-charged ions in an electron beam ion trap (EBIT). Three cases are studied: the continuous neutral gas injection, ion source injection, and evaporative cooling. The effects of the neutral gas density, axial potential, and the beam current density on the ions evolution are discussed.

The optical transition probability of Nd3+ (0.5 mol%) doped lanthanum-modified lead zirconate titanate (PLZT) is investigated. The absolute intensities of its forced electric dipole transitions between 400 nm and 1000 nm were measured, from which we obtain three phenomenological parameters, Ω2 = 0.787×10−20 cm2, Ω4 = 1.182×10−20 cm2, and Ω6 = 1.042×10−20 cm2, according to the Judd–Ofelt theory. The radiation lifetime (346.9 μs) of the 4F3/2 metastable state, the stimulated emission cross-section σij (2.49×10−21 cm2, 6.51×10−21 cm2, 2.17×10−21 cm2) and the fluorescence branch ratios are calculated. We also measured the fluorescence lifetime (155.84 μs) and calculated the quantum efficiency (46.1%). The analysis reveals that Nd3+-doped PLZT, based on its large electro-optical effect, has potential applications in active optical devices.

We investigate the polarized emission behaviour of an Eu3+ doped azo-polymer waveguide. Affected by the azobenzene groups in the photoinduced orientation process by the 532 nm linearly polarized laser, the ligands were realigned orderly perpendicular to the direction of the orientation direction. This leads to the polarized absorption and emission of the waveguide in the orientation direction. By an m-line apparatus based on the prism coupling technique, two guided propagation modes were observed in the waveguide, and the refractive index at 650 nm in TE polarizations is 1.7505.

The propagation of a normal incident electromagnetic plane wave in a mixture of rare plasma and dense neutral gas is investigated by one dimensional model. The numerical results show that the amplitude of wave electric field is decayed dramatically and its phase is modulated obviously in a distance of a few wave lengthes due to the frequent collisions between electrons and neutrals (the collision frequency ?c is near or even larger than the wave frequency ?0).