Investigation of one-way absorption properties in an asymmetric photonic crystal containing a semiconductor defect.

We theoretically study the one-way absorption in two 1D defective asymmetric photonic crystals, air/(DB)A(BD)/air and air/(DB)A(BD)A(DB)A(BD)/air, where A and B are dielectrics, D is the semiconductor, n-InSb, and N, M are stack numbers with N≠M. It is revealed that their absorption spectra exhibit one-way properties. We also find that the number of one-way absorption peaks depends on the symmetry and number of defect layers, which are similar to the defect modes in the transmittance spectra of the usual symmetry photonic crystals.

Wave properties in asymmetric single-negative-base photonic crystals.

We theoretically study wave properties for one-dimensional defective asymmetric photonic crystals, air/(AB)G(BA)/air, air/(AQ)G(QA)/air, and air/(BQ)G(QB)/air, where A is a lossy epsilon-negative material, B is a lossy mu-negative material, G and Q are dielectrics with different refractive indexes, and M and N are stack numbers with M≠N. Special attention has been paid to their absorption spectra. It is found that at certain frequencies the absorption can exhibit unidirectional properties.

Design of a terahertz photonic crystal transmission filter containing ferroelectric material.

The ferroelectric material KTaO (KTO) has a very high refractive index, which is advantageous to the photonic crystal (PC) design. KTO polycrystalline crystal has a high extinction coefficient. In this work, we perform a theoretical study of the transmission properties of a PC bandpass filter made of polycrystalline KTO at terahertz (THz) frequencies.

Analysis of multigroup and multichannel filtering properties in a ferroelectric-dielectric periodic multilayer.

In this work, we propose a filter structure using a one-dimensional ferroelectric-dielectric periodic multilayer, air/[(ABA)C](ABA)/air, where N and N are the two numbers of periods. Here, B is a dielectric material of SiO, C is the same as B with a different thickness, and A is taken to be a ferroelectric material BaSrTiO+30%MgSiO, whose dielectric constant is very high (ϵ=439 at 10 GHz). The results show that the transmittance spectra have N-channel groups at microwave frequencies and these groups can be classified into two types.

Experimental measure of transmission characteristics of low-frequency surface plasmon polaritons in frequency and time domains.

In this work, based on the use of the concept of spoof surface plasmon polaritons (spoof SPPs), we propose a novel kind of microstrips to suppress the interference between bended parallel microstrips. This novel structure is implemented by introducing subwavelength periodic structures onto the sides of a conventional microstrip. We numerically analyze the transmission characteristics of such new microstrips.

Single-negative metamaterial periodic multilayer doped by magnetized cold plasma.

This study theoretically investigates the properties of the defect mode in a 1D defective single-negative photonic crystal containing a magnetized cold plasma defect layer. The considered photonic crystal structure is made of epsilon-negative and mu-negative metamaterials. We investigate the defect mode as a function of the thickness and the electron density of the defect layer and the magnetic field.

Magnetic-field tunable multichannel filter in a plasma photonic crystal at microwave frequencies.

The microwave magnetic-field tunable filtering properties in a multichannel filter based on use of a one-dimensional finite magnetized plasma photonic crystal (PPC) are theoretically investigated. The considered PPC has a structure of air/(AB)/air, where A is a dielectric layer, B is a plasma layer, and N is the stack number. First, in the absence of an externally applied magnetic field, the structure can work as a multichannel filter whose channel number is equal to N-1 for N>1.

Use of single-negative material as a tunable defect in a dielectric photonic crystal heterostructure.

The defect mode in a photonic crystal heterostructure of (1/2) N (2/1)N tuned by using a single-negative layer as a defect layer; that is, the structure to be considered is (1/2)ND (2/1)N, where 1, 2 are dielectrics, N is the stack number, and D is a defect layer taken to be a single-negative material. The results show that when D is a mu-negative (μ < 0) medium, the defect mode frequency is redshifted as a function of the thickness of D as well as the static permittivity. On the other hand, if D is an epsilon-negative (ε < 0) medium, the defect mode frequency is blueshifted as the defect layer thickness increases, but it is independent of the static permeability.

Photonic band gap structure for a ferroelectric photonic crystal at microwave frequencies.

In this work, the photonic band gap (PBG) structure in a one-dimensional ferroelectric photonic crystal (PC) is theoretically investigated. We consider a PC, air/(AB)/air, in which layer A is a dielectric of MgO and layer B is taken to be a ferroelectric of BaSrTiO (BSTO). With an extremely high value in the dielectric constant in BSTO, the calculated photonic band structure at microwave frequencies exhibits some interesting features that are significantly different from those in a usual dielectric-dielectric PC.

Analysis of defect mode in a one-dimensional symmetric double-negative photonic crystal containing magnetized cold plasma defect.

In this paper, the characteristic matrix method is employed to theoretically investigate properties of the defect mode in a 1D lossy symmetric defective photonic crystal containing two magnetized cold plasma defect layers. The considered photonic crystal is made of double-negative and double-positive materials. The defect mode, as a function of the magnetic field and the electron density, will be investigated in three different structures.

Properties of Transmission and Leaky Modes in a Plasmonic Waveguide Constructed by Periodic Subwavelength Metallic Hollow Blocks.

Based on the concept of low-frequency spoof surface plasmon polaritons (spoof SPPs), a kind of leaky mode is proposed in a waveguide made of a subwavelength metal-block array with open slots. Numerical results reveal that a new transmission mode is found in the periodic subwavelength metal open blocks. This modal field is located inside the interior of a hollow block compared with that in a solid metal block array.

Analysis of tunable negative refraction in a lossy and extrinsic semiconductor.

In this work, within the framework of an inhomogeneous wave, we study the wave transmission at the boundary between air and a lossy extrinsic semiconductor of n-type indium antimonide. Transmission properties such as negative refraction are specifically investigated. The choice of such a semiconductor enables us to study the tunable features in the negative refraction because its permittivity is a function of the frequency, the temperature, and the doping concentration.

Near-infrared photonic band structure in a semiconductor metamaterial photonic crystal.

In this study, we theoretically investigate the near-infrared (NIR) photonic band structure (PBS) in a one-dimensional semiconductor metamaterial (MM) photonic crystal (PC). The considered PC is (AB), where N is the stack number, A is a dielectric, and B is a semiconductor MM composed of Al-doped ZnO and ZnO. It is found that the photonic band gaps (PBGs) can be tunable by the variations in filling factor, and thicknesses of A and B.

Differential microstrip lines with reduced crosstalk and common mode effect based on spoof surface plasmon polaritons.

We apply the concept of spoof surface plasmon polaritons (SPPs) to the design of differential microstrip lines by introducing periodic subwavelength corrugations on their edges. The dispersion relation and field distribution of those lines are analyzed numerically. And then through designing practical coupling circuits, we found that compared with conventional differential microstrip lines, the electromagnetic field can be strongly confined inside the grooves of the corrugated microstrip lines, so the crosstalk between the differential pair and the adjacent microstrip lines is greatly reduced, and the conversion from the differential signal to the common mode signal can also be effectively suppressed.

Design of multichannel filters based on the use of periodic Cantor dielectric multilayers.

A fractal multilayer structure made of two dielectric materials can exhibit photonic bandgap (PBG). In this work, with the use of this PBG, we study the transmission properties of periodic triadic Cantor set structures. The results indicate that the structure can be used to design multichannel filters with channel number equal to N-1 for a given number of periods, N.

Sensitivity enhancement of electro-optic polymer probing system using photo-isomerization and Fabry-Pérot effects.

A sensitivity enhancement method for an external electro-optic (EO) probing system using a poled polymer as an EO sensor is proposed. A pumping laser, which induces the photo-isomerization effect in a prepoled EO polymer, and a tunable probing laser, which induces Fabry-Pérot effect, are combined to enhance the polymer EO sensor sensitivity. Results of an experiment with an EO sensor made of Disperse Red 1 poly(methy1 methacrylate) that demonstrates this combined effect are reported.

Superior liver sparing by combined coplanar/noncoplanar volumetric-modulated arc therapy for hepatocellular carcinoma: a planning and feasibility study.

Compared with step-and-shoot intensity-modulated radiotherapy (sIMRT) and tomotherapy, volumetric-modulated arc therapy (VMAT) allows additional arc configurations in treatment planning and noncoplanar (NC) delivery. This study was first to compare VMAT planning with sIMRT planning, and the second to evaluate the toxicity of coplanar (C)/NC-VMAT treatment in patients with hepatocellular carcinoma (HCC). Fifteen patients with HCC (7 with left-lobe and 8 with right-lobe tumors) were planned with C-VMAT, C/NC-VMAT, and sIMRT.

Early detection of Lewis lung carcinoma tumor control by irradiation using diffusion-weighted and dynamic contrast-enhanced MRI.

Purpose: To investigate the correlation between diffusion-weighted (DW) and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) derived parameters and radioresponsiveness of Lewis lung carcinoma (LLC) tumor.

Materials And Methods: LLC tumor growth in C57BL/6 mouse limb was used for the experiment. The tumors were irradiated with 10 Gy×5, or 30 Gy×2 vs.

Use of two-dimensional nanorod arrays with slanted ITO film to enhance optical absorption for photovoltaic applications.

Two-dimensional (2D) Si-nanorod arrays offer a promising architecture that has been widely recognized as attractive devices for photovoltaic applications. To further reduce the Fresnel reflection that occurs at the interface between the air and the 2D Si-nanorod array because of the large difference in their effective refractive indices, we propose and adopt a slanted ITO film as an intermediate layer by using oblique-angle sputtering deposition. The nearly continuous surface of the slanted ITO film is lossless and has high electrical conductivity; therefore, it could serve as an electrode layer for solar cells.

Programmable segmented volumetric modulated arc therapy for respiratory coordination in pancreatic cancer.

We programmably divided long-arc volumetric modulated arc therapy (VMAT) into split short arcs, each taking less than 30s for respiratory coordination. The VMAT plans of five pancreatic cancer patients were modified; the short-arc plans had negligible dose differences and satisfied the 3%/3-mm gamma index on a MapCHECK-2 device.

Volumetric modulated arc therapy for nasopharyngeal carcinoma: a dosimetric comparison with TomoTherapy and step-and-shoot IMRT.

Purpose: Volumetric modulated arc therapy (VMAT), a novel technique, employs a linear accelerator to conduct dynamic modulation rotation radiotherapy. The goal of this study was to compare VMAT with helical tomotherapy (HT) and step-and-shoot intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC) patients with regard to the sparing effect on organs at risk (OARs), dosimetric quality, and efficiency of delivery.

Materials And Methods: Twenty patients with NPC treated by HT were re-planned by VMAT (two arcs) and IMRT (7-9 fields) for dosimetric comparison.

Practically acquired and modified cone-beam computed tomography images for accurate dose calculation in head and neck cancer.

Background: On-line cone-beam computed tomography (CBCT) may be used to reconstruct the dose for geometric changes of patients and tumors during radiotherapy course. This study is to establish a practical method to modify the CBCT for accurate dose calculation in head and neck cancer.

Patients And Methods: Fan-beam CT (FBCT) and Elekta's CBCT were used to acquire images.

Terahertz multichanneled filter in a superconducting photonic crystal.

Terahertz spectroscopic properties in a one-dimensional superconductor-dielectric photonic crystal are theoretically investigated. Based on the calculated results, a terahertz multichanneled transmission filter can be achieved within the photonic passband. This structure possesses the comb-like resonant peaks in transmission spectrum at low temperature.

Analysis of photonic band structure in a one-dimensional photonic crystal containing single-negative materials.

A theoretical analysis on the angle- and thickness-dependent photonic band structure in a one-dimensional photonic crystal containing single-negative (SNG) materials is presented. The photonic crystal consists of two alternating SNG materials, including that one has a negative permittivity (ENG) and the other has a negative permeability (MNG). It is found that there are two types of SNG gaps.

Noncontact electrical test of a ball grid array substrate that uses the electro-optic probing technique.

A new technique for testing a ball grid array (BGA) package substrate that uses the electro-optic (EO) probing technique is investigated. This technique can detect open circuits in the BGA substrate with a high spatial resolution. An experimental setup that uses an EO probe tip made of LiNbO3 crystal is reported along with the measurement results from a real BGA substrate.