Giant Goos-Hanchen displacement enhanced by dielectric film in frustrated total internal reflection configuration

It is predicted that the Goos-Hanchen displacement in the usual frustrated total internal reflection configuration can be resonantly enhanced greatly by coating a dielectric thin film onto the surface of the first prism when the angle of incidence is larger than the critical angle for total reflection at the prism-vacuum interface and is smaller than but close to the critical angle for total reflection at the prism-film interface. Theoretical analysis shows that the displacement of transmitted beam is about half the displacement of reflected beam in the thick limit of the vacuum gap between the two prisms. This is to be compared with the relation in the usual symmetric double-prism configuration that the displacement of transmitted beam is equal to the displacement of reflected beam. Numerical simulations for a Gaussian incident beam of waist width of 100 wavelengths reveal that when the dielectric thin film is of the order of wavelength in thickness, both the reflected and transmitted beams maintain well the shape of the incident beam in the thick limit of the vacuum gap. So largely enhanced displacements would lead to applications in optical devices and integrated optics. (c) 2007 American Institute of Physics.

Experimental observation of negative lateral displacements of microwave beams transmitting through dielectric slabs

It was theoretically predicted that when a beam of light travels through a thin slab of optically denser medium in the air, the emerging beam from the slab will suffer a lateral displacement that is different from the prediction of geometrical optics, that is, the Snell's law of refraction and can be zero and negative as well as positive. These phenomena have been directly observed in microwave experiments in which large angles of incidence are chosen for the purpose of obtaining negative lateral displacements. (C) 2005 Elsevier B.V. All rights reserved.

Negative lateral shift of a light beam transmitted through a dielectric slab and interaction of boundary effects

It is found that when a light beam travels through a slab of optically denser dielectric medium in air, the lateral shift of the transmitted beam can be negative. This is a novel phenomenon that is reversed in comparison with the geometrical optic prediction according to Snell's law of refraction. A Gaussian-shaped beam is analyzed in the paraxial approximation, and a comparison with numerical simulations is made. Finally, an explanation for the negativity of the lateral shift is suggested, in terms of the interaction of boundary effects of the slab's two interfaces with air.

Large positive and negative lateral displacements from total internal reflection configuration with a weakly absorbing dielectric film

It is theoretically shown that the simultaneously large positive and negative lateral displacements will appear when the resonant condition is satisfied for a TE-polarized light beam reflected from the total internal reflection configuration with a weakly absorbing dielectric film. Appearance of the enhanced negative lateral displacement is relative to the incidence angle, absorption of the thin Elm and its thickness. If we select an appropriate weakly absorbing dielectric film and its thickness, the simultaneously enhanced positive and negative lateral displacements will appear at different resonant angles. These phenomena may lead to convenient measurements and interesting applications in optical devices.

Large and negative lateral displacement in an active dielectric slab configuration

We investigate the large negative lateral displacements of TE polarized light beams reflected from or transmitted through an active slab surrounded by transparent medium. The large negative displacements can be achieved when the incidence angle of the beam is less than but close to the critical angle for total reflection. It is also shown that both the reflectivity and transmissivity of the beam that correspond to the large negative displacements can be enhanced by active medium. These phenomena may lead to convenient measurements and interesting applications in optical devices. (c) 2006 Elsevier B.V. All rights reserved.

CALCULATION OF DIELECTRIC-CONSTANTS FOR SEMICONDUCTORS - AN APPLICATION OF ABINITIO PSEUDOPOTENTIAL METHOD

We have used ab initio pseudopotential method to generate basis wavefunctions and eigen energies to carry out first principle calculations of the static macroscopic dielectric constant for GaAs and GaP. The resulted converged random phase approximation (RPA) value is 12.55 and 10.71, in excellent agreement to the experimental value of 12.4 and 10.86, respectively. The inclusion of the exchange correlation contribution makes the calculated result slightly worsen. A convergence test with respect to the number of k points in Brillouin zone (BZ) integration was carried out. Sixty irreducible BZ k points were used to achieve the converged results. Integration with only 10 special k points increased the RPA value by 15%.

ENHANCEMENT EFFECT OF PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITED SIN CAPPING LAYER ON DIELECTRIC CAP QUANTUM-WELL DISORDERING

Quantum well disordering of GaAs/AlGaAs multiple quantum well(MQW) has been accomplished with only plasma enhanced chemical vapor deposited (PECVD) SiN cap layer growth. The amount of blue shift increases with SiN growing time. This result has been explained by the vacancy indiffusion during PECVD SiN growth. Rapid thermal annealing (RTA) of the sample after SiN cap layer growth at 850 degrees C for 35 s caused a larger amount of blue shift than those obtained without RTA. By considering the model of Al diffusion from AlGaAs barrier into GaAs QWs together with the result from photoluminescence (PL) measurement, Al diffusion coefficients were calculated. The Al diffusion coefficient due to PECVD SiN was estimated at about 3 x10(-17) cm(2)/s. It was possible to extract the effect of RTA on the QW disordering, which showed that the amount of the blue shift and the Al diffusion coefficient due only to RTA increases with SiN cap layer thickness as reported by Chi et al.(10))

Modulation of Photonic Bandgap and Localized States by Dielectric Constant Contrast and Filling Factor in Photonic Crystals

The band structure of 2D photonic crystals (PCs) and localized states resulting from defects are analyzed by finite-difference time-domain (FDTD) technique and Pade approximation. The effect of dielectric constant contrast and filling factor on photonic bandgap (PBG) for perfect PCs and localized states in PCs with point defects are investigated. The resonant frequencies and quality factors are calculated for PCs with different defects. The numerical results show that it is possible to modulate the location, width and number of PBGs and frequencies of the localized states only by changing the dielectric constant contrast and filling factor.

Applications of dielectric thin film by electron cyclotron resonance plasma chemical vapor deposition for semiconductor photoelectronic devices

The paper reports a method of depositing SiO2, SiNx, a:Si, Si3N4 and SiOxNy dielectric thin films by electron cyclotron resonance plasma chemical vapor deposition (ECR CVD) on InP, InGaAs and other compound semiconductor optoelectronic devices,and give a technology of depositing dielectric thin films and optical coatings by ECR CVD on Laser's Bars. The experiment results show the dielectric thin films and optical coatings are stable at thermomechanical property,optical properties and the other properties. In addition, the dielectric thin film deposition that there is low leakage current is reported for using as diffusion and ion implatation masks in the paper. In the finally, the dielectric film refractive index can be accurately controlled by the N-2/O-2/Ar gas flow rate.

Dielectric properties of Bi2Ti2O7 films grown on Si(100) substrate by APMOCVD

The growth of Bi2Ti2O7 films with (111) orientation on Si(100) substrate by atmospheric pressure metal-organic chemical vapor deposition(APMOCVD) technique at 480similar to550 degreesC is presented. The films were characterized by X-ray diffraction analysis, atomic force microscopy and electron diffraction. The results show high quality Bi2Ti2O7 films with smooth shinning surface. The dielectric properties and C-V characterization of the films were studied. The dielectric constant (epsilon) and loss tangent (tgdelta) were found to be 180 and 0.01 respectively. The charge storage density was 31.9fC/mum(2). The resistivity is higher than 1x10(12) Omega. .cm under the applied voltage of 5V. The Bi2Ti2O7 films are suitable to be used as a new insulating gate material in dynamic random access memory (DRAM).