A Kind of Biomolecular Probe Sensor Based on TFBG Surface Plasma Resonance

This paper reports the application of the biomolecular probe sensor based on the tilted fiber Bragg grating （TFBG） surface plasma resonance （SPR） which can recognize the specificity of the specific molecule by depositing sensitive biological membrane outside the active golden layer. The method of self-assembly was used to make the fixed sensitive biological membrane to achieve the best effect in the experiment. To illustrate the specific recognition of the DNA molecule, the TFBG-SPR biosensor was exposed to complementary DNA solutions with the concentration of 0.1 mmol/L and 0.05 mmol/L, respectively. The resonance wavelength of the TFBG-SPR biosensor increased gradually, indicating that the hybridization with the complementary DNA molecules changed the effective refractive index in the vicinity of the golden layer. Furthermore, the results illustrated the feasibility of the biomolecular probe sensor based on the TFBG surface plasma resonance for detecting the specific molecule.

Relative Irradiance Measurement and Bonding Configurations of Amorphous Fluorinated Carbon Films Deposited by Electron Cyclotron Resonance Plasma

a-C:F films are deposited by microwave electron cyclotron resonance (ECR)plasma chemical vapor deposition (CVD) using trifluoromethane (CHF3) and benzene (C6H6) as source gases at different microwave powers. The radicals in plasma originating from source gases dissociation are analyzed by relative irradiance measurement. The bonding configurations and binding state of a-C:F films are measured with Fourier-transformed infrared spectrometer (FTIR) and x-ray photoelectron spectroscopy (XPS). The results show that a-C:F films are mainly composed of CF radical at lower powers but of CF2 radical at higher powers. The deposition of films is related to the radicals generated in plasma and the main bonding configurations are dependent on the ratio of CF to CF2 radicals in films.

Simulation of nonlinear behavior in an electron cyclotron resonance plasma

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.

Correlation ofⅢ/Ⅴsemiconductor etch results with physical parameters of high-density reactive plasmas excited by electron cyclotron resonance

Reactive ion etching is the interaction of reactive plasmas with surfaces. To obtain a detailed understanding of this process, significant properties of reactive composite low-pressure plasmas driven by electron cyclotron resonance（ECR） were investigated and compared with the radial uniformity of the etch rate. The determination of the electronic properties of chlorine-and hydrogen-containing plasmas enabled the understanding of the pressure-dependent behavior of the plasma density and provided better insights into the electronic parameters of reactive etch gases. From the electrical evaluation of I（V） characteristics obtained using a Langmuir probe,plasmas of different compositions were investigated. The standard method of Druyvesteyn to derive the electron energy distribution functions by the second derivative of the I（V）characteristics was replaced by a mathematical model which has been evolved to be more robust against noise, mainly, because the first derivative of the I（V） characteristics is used. Special attention was given to the power of the energy dependence in the exponent. In particular, for plasmas that are generated by ECR with EM modes, the existence of Maxwellian distribution functions is not to be taken as a self-evident fact, but the bi-Maxwellian distribution was proven for Ar-and Kr-stabilized plasmas. In addition to the electron temperature, the global uniform discharge model has been shown to be useful for calculating the neutral gas temperature. To what extent the invasive method of using a Langmuir probe could be replaced with the noninvasive optical method of emission spectroscopy, particularly actinometry, was investigated,and the resulting data exhibited the same relative behavior as the Langmuir data. The correlation with etchrate data reveals the large chemical part of the removal process—most striking when the data is compared with etching in pure argon. Although the relative amount of the radial variation of plasma density and etch rate is approximately ？5%, the etch rate shows a slightly concave shape in contrast to the plasma density.

Wakefield Resonant Excitation by Intense Laser Pulse in Capillary Plasma

The laser-induced plasma wakefield in a capillary is investigated on the basis of a simple two-dimensional analytical model. It is shown that as an intense laser pulse reshaped by the capillary wall propagates in capillary plasma, it resonantly excites a strong wakefield if a suitable laser pulse width and capillary radius are chosen for a certain plasma density. The dependence of the laser width and capillary radius on the plasma density for resonance conditions is considered. The wakefield amplitude and longitudinal scale of bubbles in capillary plasma are much larger than those in unbounded plasma, so the capillary guided plasma wakefield is more favorable to electron acceleration.

Interaction between plasma and electromagnetic field in ion source of 10 cm ECR ion thruster

Through diagnosing the plasma density and calculating the intensity of microwave electric field,four 10 cm electron cyclotron resonance(ECR)ion sources with different magnetic field structures are studied to reveal the inside interaction between the plasma,magnetic field and microwave electric field.From the diagnosing result it can be found that the plasma density distribution is controlled by the plasma generation and electron loss volumes associated with the magnetic field and microwave power level.Based on the cold plasma hypothesis and diagnosing result,the microwave electric field intensity distribution in the plasma is calculated.The result shows that the plasma will significantly change the distribution of the microwave electric field intensity to form a bow shape.From the boundary region of the shape to the center,the electric field intensity varies from higher to lower and the diagnosed density inversely changes.If the bow and its inside lower electric field intensity region are close to the screen grid,the performance of ion beam extracting will be better.The study can provide useful information for the creating of 10 cm ECR ion source and understanding its mechanism.

Resonant magneto-optical Kerr effect induced by hybrid plasma modes in ferromagnetic nanovoids

With nanovoids buried in Co films, resonant structures were observed in spectra of polar magneto-optical Kerr effect（MOKE）, where both a narrow bandwidth and high intensity were acquired. Through changing the thickness of Co films and the lattice of voids, different optical modes were introduced. For a very shallow array of voids, the resonant MOKE was induced by Ag plasma edge resonance, for deeper ones, hybrid plasma modes, such as void plasmons in the voids, surface lattice plasmons between the voids, and the co-action of them, etc. resulted in resonant MOKE. We found that resonant MOKE resulted from the void plasmons resonance which possesses the narrowest bandwidth for the lowest absorption of voids. The simulated electromagnetic field（EF） distribution consolidated different effects of these three optical modes on resonant MOKE modulation. Such resonant polar MOKE possesses high sensitivity, which might pave the way to on-chip MO devices.

Development of plasma sources for Dipole Research EXperiment(DREX)

Dipole Research EXperiment（DREX） is a new terrella device as part of the Space Plasma Environment Research Facility（SPERF） for laboratory studies of space physics relevant to the inner magnetospheric plasmas. Adequate plasma sources are very important for DREX to achieve its scientific goals. According to different research requirements, there are two density regimes for DREX. The low density regime will be achieved by an electron cyclotron resonance（ECR） system for the ‘whistler/chorus＇ wave investigation, while the high density regime will be achieved by biased cold cathode discharge for the desired ‘Alfvén＇ wave study. The parameters of ‘whistler/chorus＇ waves and ‘Alfvén＇ waves are determined by the scaling law between space and laboratory plasmas in the current device. In this paper, the initial design of these two plasma sources for DREX is described. Focus is placed on the chosen frequency and operation mode of the ECR system which will produce relatively low density ‘artificial radiation belt＇ plasmas and the seed electrons, followed by the design of biased cold cathode discharge to generate plasma with high density.

Understanding hydrogen plasma processes based on the diagnostic results of 2.45 GHz ECRIS at Peking University

Optical emission spectroscopy（OES）, as a simple in situ method without disturbing the plasma, has been performed for the plasma diagnosis of a 2.45 GHz permanent magnet electron cyclotron resonance（PMECR） ion source at Peking University（PKU）. A spectrum measurement platform has been set up with the quartz-chamber electron cyclotron resonance（ECR） ion source [Patent Number： ZL 201110026605.4] and experiments were carried out recently. The electron temperature and electron density inside the ECR plasma chamber have been measured with the method of line intensity ratio of noble gas. Hydrogen plasma processes inside the discharge chamber are discussed based on the diagnostic results. What is more, the superiority of the method of line intensity ratio of noble gas is indicated with a comparison to line intensity ratio of hydrogen. Details will be presented in this paper.

Left-handed properties of a composite structure with metallic wires in a homogeneous Lorentz medium

The electromagnetic properties of a composite structure with metallic wires in a Lorentz medium were studied. The results show that the electromagnetic properties of the medium host influence the plasma resonance of metallic wires and the left-handed character of the composite. The plasma frequency of metallic wires reduces with the rise of permittivity or permeability of the medium host. Also, the negative permeability of the medium can destroy the wires’ plasma resonance and prevent the realization of left-handed properties. The high loss of medium permittivity or permeability also inhibits the metallic plasma resonance. The negative influence of the media host on the left-handed properties of the composite structure can be effectively reduced by proper structure design, such as introducing a nonmagnetic medium in the host or using an anisotropic medium.

One-pot Synthesis of Mesostructured Ag/Siliea Composite Films

Mesoporous silica films embedded with Ag nanoparticles were directly synthesized by a solgel dip-coating process, combining alkyl （ethylene oxide） surfactant as temple and tetraethoxysilane as inorganic precursor. The addition of Ag^＋ ion to the reaction sol was prior to the formation of films, followed by the heat treatment at 150℃ led to the creation ofAg nanoparticies. The formation ofAg nanoparticles and the change of its surface plasma resonance absorption were characterized by Uv-vis. The small angle XRD test indicated that the films had an ordered hexagonal mesoporous structure, of which the unit cell parameter was about 4.26 nm. The TEM images and EDS spectra of the samples have directly verified the presence of mono-dispersed Ag nanoparticles within the films, due to the confine effects of mesopores.

High sensitivity dual core photonic crystal fiber sensor for simultaneous detection of two samples

The optical control ability of photonic crystal fiber(PCF)is a distinctive property suitable for improving sensing and plasma performance.This article proposes a dual-core D-channel PCF sensor that can detect two samples simultaneously,which effectively solves the problems of coating difficulty and low wavelength sensitivity.The PCF has four layers of air holes,which dramatically reduces the optical fiber loss and is more conducive to the application of sensors in actual production.In addition,by introducing dual cores on the upper and lower sides of the central air hole,reducing the spacing between the core and the gold nanolayer,a stronger evanescent field can be generated in the cladding air hole.The optical fiber sensor can detect the refractive index of two samples simultaneously with a maximum sensitivity of 21300 nm/RIU.To the best of our knowledge,the sensitivity achieved in this work is the highest sensitivity with the dual sample synchronous detection sensors.The detection range of the refraction index is 1.35-1.41,and the resolution of the sensor is 4.695×10^(-6).Overall,the sensor will be suitable for medical detection,organic chemical sensing,analyte detection,and other fields.

Photonic crystal fiber polarization filter with two large apertures coated with gold layers

A novel photonic crystal fiber（PCF） polarization filter is designed and fabricated; it consists of two large apertures coated with gold. The asymmetric structure separates the resonance position in the vertical direction well. Due to the metal layer covering, loss is greatly improved. Finite element method is applied for numerical simulation. The influences of varying gold thickness and varying the diameters and the center positions of the larger apertures on filtering performance are evaluated. Theory of coupling between surface plasma and core mode is introduced. By modulating the parameters, we realize a single polarization filter at 1.31 μm and 1.55 μm. The basal mode loss in the y direction can reach 1408.80 dB/cm at 1.31 μm and 1911.22 dB/cm at 1.55 μm respectively, but basal mode loss in the x direction is relatively small, 0.82 dB/cm and 1.87 dB/cm. In addition, two kinds of broadband polarization filters are proposed. If the fiber length is set to 200 μm,the extinction ratio is greater than 20 dB with width of 570 nm and 490 nm. The filter has simple structure and excellent performance.

Optical cavity resonance with magnetized plasma

Indefinite media with mixed signs of dielectric tensor elements possess unbounded equifrequency surfaces that have been utilized for diverse applications such as superimaging, enhanced spontaneous emission, and thermal radiation. One particularly interesting application of indefinite media is an optical cavity supporting anomalous scaling laws. In this Letter, we show that by replacing an indefinite medium with magnetized plasma one can construct a tunable indefinite cavity. The magnetized plasma model is based on realistic semiconductor material properties at terahertz frequencies that show hyperbolic dispersion in a certain frequency regime. The hyperbolic dispersion features are utilized for the design of optical cavities. Dramatically different sizes of cavities can support the same resonance mode at the same frequency. For a cavity of fixed size, the anomalous scaling law between the resonance frequency and mode number is confirmed. The resonance frequency can be strongly modulated by changing the strength of the applied magnetic field. The proposed model provides active controllability of terahertz resonances on the deep subwavelength scale with realistic semiconductor materials.

Plasma perturbations in the coexisting environment of VLF transmitter emission, lightning strokes and seismic activity

We analyzed plasma perturbations occurring in the coexisting environment of powerful VLF transmitter emission, intense lightning strokes and strong seismic activity during pregnant period. The results suggest that anomalous electron bursts with energy dispersion in the range of ~100–350 keV, forming the "wisp" signature, are due to cyclotron resonance of electrons with monochromatic waves from the powerful NWC VLF transmitters during nighttime. The intense broad band VLF emissions (up-going 0+ whistlers) are observed while the DEMETER satellite goes through the region of intense thunderstorm activities at mid-latitudes. However, the effects of intense lightning activity and pregnant earthquake have little impact on this kind of stable energy-dispersed electron structures, despite the fact that they are presumably two primary reasons for the particle precipitation in the ionosphere. The case studied here provides us a valuable opportunity to address the various sources triggering the anomalous plasma perturbations in the ionosphere.

Plasma parameter diagnosis using hydrogen emission spectra of a quartz-chamber 2.45 GHz ECRIS at Peking University

A quartz-chamber 2.45 GHz electron cyclotron resonance ion source(ECRIS) was designed for diagnostic purposes at Peking University [Patent Number: ZL 201110026605.4]. This ion source can produce a maximum 84 m A hydrogen ion beam at 50 k V with a duty factor of 10%. The root-mean-square(RMS) emittance of this beam is less than 0.12π mm mrad. In our initial work,the electron temperature and electron density inside the plasma chamber had been measured with the line intensity ratio of noble gases. Based on these results, the atomic and molecular emission spectra of hydrogen were applied to determine the dissociation degree of hydrogen and the vibrational temperature of hydrogen molecules in the ground state, respectively. Measurements were performed at gas pressures from 4×10^(-4) to 1×10^(-3) Pa and at input peak RF power ranging from 1000 to 1800 W. The dissociation degree of hydrogen in the range of 0.5%-10% and the vibrational temperature of hydrogen molecules in the ground state in the range of 3500-8500 K were obtained. The plasma processes inside this ECRIS chamber were discussed based on these results.

Principle and Experiment of Protein Detection Based on Optical Fiber Sensing

A method for detecting protein molecules based on the tilted fiber Bragg grating （TFBG） surface plasma resonance （SPR） is proposed to achieve the quick online real-time detection of trace amount of proteins. The detection principles of the TFBG-SPR protein molecular probe are analyzed, and its feasibility is demonstrated. The intermediary material between the protein molecules and the golden layer outside of the fiber gratings is cysteamine hydrochloride. When the concentration of the cysteamine hydrochloride solution is 2 M, the shift of the TFBG resonance peak is 2.23 nm, illustrating that the cysteamine hydrochloride modifies the gold film successfully. IgG antigen solution is poured on the surface of the cysteamine hydrochloride modifying the gold-deposited TFBG. Finally, antigen-antibody hybridization experiment is carried out with a 10mg/mL antibody solution, and after two hours of hybridization the resonance peak of the TFBG shifts 5.1 nm, which validates the feasibility and effectiveness of the TFBG-SPR protein molecular probe.

Simultaneous red-green-blue electroluminescent enhancement directed by surface plasmonic ＂far-field＂ of facile gold nanospheres

Based on the ＂far-field＂ effect of surface plasma resonance, simultaneous red-green-blue electroluminescence enhancement by facile synthesized gold nanospheres were realized in this work, which would be difficult and complex to attain using wavelength-selected localized surface plasma resonance. The plasmonic ＂far-field＂ effect can simultaneously enhance the whole emission region in the white light range, because the enhancing regions from blue to red emission are largely overlapped. By doping gold nanospheres embedded in a poly（3,4-ethylene dioxythiophene）：polystyrene sulfonic acid （PEDOT：PSS） layer, yield enhancement is achieved in more than 95% devices with the best enhancing ratio of 60% and the commission International de UEclairage （CIE） coordinate is stable at approximately （0.33, 0.36）. The plasmonic ＂far-field＂ effect requires an ultra-low working concentration of Au NPs in picomolar magnitude, and shows little negative effect on the electronic process and light scattering, which has big potential in realizing highly efficient white organic light emitting diodes.