Theoretical analysis of two nonpolarizing beam splitters in asymmetrical glass cubes

The design principle for a nonpolarizing beam splitter based on the Brewster condition in a cube is introduced. Nonpolarizing beam splitters in an asymmetrical glass cube are proposed and theoretically investigated, and applied examples are given. To realize 50% reflectance and 50% transmittance at specified wavelengths for both polarization components with an error of less than 2%, two measurements are taken by adjusting the refractive index of the substrate material and optimizing the thicknesses of each film in the design procedures. The simulated results show that the targets are achieved using the method reported here.     

Design and analysis of all-dielectric broadband nonpolarizing parallel-plate beam splitters

Past research on the all-dielectric nonpolarizing beam splitter is reviewed. With the aid of the needle thin-film synthesis method and the conjugate graduate refine method, three different split ratio nonpolarizing parallel-plate beam splitters over a 200 nm spectral range centered at 550 nm with incidence angles of 45 degrees are designed. The chosen materials component and the initial stack are based on the Costich and Thelen theories. The results of design and analysis show that the designs maintain a very low polarization ratio in the working range of the spectrum and has a reasonable angular field.     

Application of a Shack cube as a beam splitter in interferometers with a local reference beam

A different setup of the Mach-Zehnder interferometer for testing the convergent wave front is described. A Shack cube is used to replace a traditional recollimator and a parallel-plate beam splitter. An equivalent pupil model has been suggested that describes the point diffraction mechanism. The calibration procedures for the Mach-Zehnder interferometer are described. The Shack-cube beam splitter has the advantages of compactness and better reference-beam quality compared with the recollimator and the parallel-plate beam splitter.     

Beam splitter layer emission in fourier-transform infrared interferometers

The self-emission from the splitting layer of a Fourier-transform infrared interferometer is modeled with basic properties of optical thin films. The resulting equation gives explicitly the self-emission contribution in terms of the temperature, the complex refractive index, the reflection coefficient, and the thickness of the beam splitter layer.     

Polarization properties and fractional-power analysis of coated and uncoated parallel-slab multireflection beam splitters

The polarization properties of coated and uncoated parallel-slab multireflection beam splitters are investigated. In a recent study [Opt. Lett. 21, 1709 (1996)] it was shown that the parallel-slab beam splitter is a basic optical component of the parallel-slab division-of-amplitude photopolarimeter. The ellipsometric parameters and the fractional powers for multireflected components generated by this system are analyzed. Interesting new observations with respect to the polarization properties at the Brewster angle of incidence and the distribution of powers among the multireflected components are presented.     

Designs of infrared nonpolarizing beam splitters with a Ag layer in a glass cube

A novel design of a nonpolarizing beam splitter with a Ag layer in a cube was proposed and optimized, based on the needle optimization. The digital simulations of the reflectance and reflection-induced retardance were presented. The simulation results showed that both the amplitude and the phase characteristics of the nonpolarizing beam splitter could realize the design targets. The difference between the simulated and the target reflectance of 50% is less than 0.4% and the simulated and the reflection-induced retardance is less than 0.62 degrees in the 1260 -1360 nm range for both p and s components.     

Symmetrically coated pellicle beam splitters for dual quarter-wave retardation in reflection and transmission

A trilayer pellicle that consists of a high-index center layer that is symmetrically coated on both sides by a low-index film can be designed to produce differential reflection and transmission phase shifts of +/- 90 degrees at oblique incidence and equal throughput for the p and the s polarizations. Such a device splits a beam of incident linearly polarized light into two orthogonal circularly polarized components that travel in well-separated angular directions. Examples of infrared dual quarter-wave retarders that use a symmetrically coated Ge pellicle at 77 degrees angle of incidence are presented. A 50-50% splitter requires a symmetric pellicle with at least five layers. Error analysis shows that the thicknesses of the high-index layers must be tightly controlled. These circular polarization beam splitters are intended for operation with a well-collimated light source and can be used as the basis of a novel circular polarization Michelson interferometer.     

Thermal ion emission from alkali-metal vanadium bronzes

The ion emission properties of M _x V₂O₅ (M = Li, Na, K, Cs) bronzes were studied at temperatures from 480 to 700‡C in applied fields of up to 20 kV/cm. The results were used to evaluate the activation energies of alkali-metal-ion emission from the vanadium bronzes. The emission properties of the bronzes were found to correlate with their diffusion properties. The mechanisms of ion emission from vanadium bronzes are discussed. Deceased.     

Reflection coefficients of p- and s-polarized light by a quarter-wave layer: explicit expressions and application to beam splitters

The complex-amplitude reflection coefficients of p- and s-polarized light by a transparent freestanding, embedded, or deposited quarter-wave layer (QWL) are derived as explicit functions of the angle of incidence and layer refractive index. This provides the basis for the design of 50%-50% beam splitters for incident s-polarized or unpolarized light that use a high-index (e.g., TiO2 or Ge) QWL embedded in a glass cube in the visible and near infrared spectral range. These simple devices have good angular and spectral response and are insensitive to small film thickness errors to the first order.     

Axial force acting on a dielectric sphere in a focused laser beam

We present the detailed behavior of the axial force acting on a dielectric sphere exerted by the optical pressure of a focused Gaussian laser beam. Comparison is made between the numerical results and those calculated from the radiation pressure cross section. There is also a discussion as to whether the expressions for the axial force given in this paper are consistent with the previously reported experimental results. Moreover, a simple experimental method to measure the axial force on a polystyrene sphere suspended in water is demonstrated, and fairly good agreement between theoretical and experimental results was obtained.     

Thermal emission from undoped and degenerate silicon structures and from a metallic grating structure

The thermal spectral emission properties of three types of periodic grating structure were investigated: (1) a lightly doped (intrinsic-like) silicon grating, (2) a degenerate (metallic-like) silicon grating, and (3) silicon gratings coated with nickel metal. The structural dimensions of all samples were the same, with feature sizes comparable to the measurement wavelengths (2.5–25 μm). The measurement temperatures for all samples were in the range 27–740 °C. In general, it was found that the spectral emission of the metallic-like gratings depended on the parameters of the grating material and on the structural dimensions. A spectral oscillation in the wavelength range comparable to the structural dimension was observed.     

Extinction and scattering of a guided beam in a hollow dielectric waveguide.

We present a theoretical approach to the problem of mode scattering by a spherical object that is placed inside a circular dielectric waveguide. This approach is based on the separation-of-variables method for each subsystem, namely, the spherical inclusion and the circular dielectric cylinder, and on the concept of the generalized recursive T-matrix algorithm for multilayered structures. We apply the technique to the backward and the forward scattering of a quasi-optical beam in the form of the fundamental HE11 mode by a sphere inside a circular hollow dielectric waveguide. The results calculated for the perfectly conducting spherical objects inside the circular hollow dielectric waveguide are compared with corresponding measured data of the backward-and the forward-scattering characteristics at the 4-mm wave band.     

Design and development of a thin film dielectric beam combiner

A multilayer thin film device called a beam combiner for a specific photodissociation experiment was designed and developed. The device when operated at 45° angle of incidence transmits auv laser beam and reflects a visible laser beam at the same time with minimum energy loss. The efficiency of the device was found to be better than 90%.     

Thermal buckling and postbuckling analysis of a laminated composite beam with embedded SMA actuators

In this paper, the thermal buckling and postbuckling behaviours of a composite beam with embedded shape memory alloy (SMA) wires are investigated analytically. For the purpose of enhancing the critical buckling temperature and reducing the lateral deflection for the thermal buckling, the characteristics of thermal buckling are investigated through the use of the shape recovery force associated with SMA wire actuators. The results of both thermal buckling and postbuckling behaviours present quantitatively how the shape recovery force affects the thermal buckling behaviour. The analytical results show that the shape recovery force reduces the thermal expansion of the composite laminated beam, which results in both an increment of the critical buckling temperature and also a reduction of the lateral deflection of postbuckling behaviours. A new formula is also proposed to describe the critical buckling temperature of the laminated composite beam with embedded SMA wire actuators.     

CNT manipulation: inserting a carbonaceous dielectric layer beneath using electron beam induced deposition

Electron beam induced carbonaceous deposition has been carried out in the presence of water vapor at 0.4 torr pressure amidst residual hydrocarbons present in the SEM chamber. When performed at a CNT location on a Si substrate with low e beam energy (10 kV), the deposition was taking place beneath the CNT. While higher beam energy (25 kV) causing the deposition on the top surface of the CNT, in agreement with the earlier reports. The insertion of dielectric carbonaceous layer beneath the CNT allowed us to measure the I-V data along the length of the nanotube using CAFM.     

Numerical analysis of a movable dielectric gap in coaxialresonators for dielectric measurements

For the purpose of improving dielectric measurements, a movable dielectric gap in coaxial resonators is analyzed using numerical simulations. The obtained field distributions, loading factors, and resonant frequency shifts for different gap positions are presented and discussed     

Reflection and refraction of an Airy beam at a dielectric interface

Reflection and refraction of a finite-power Airy beam at the interface between two dielectric media are investigated analytically and numerically. The formulation takes into account the paraxial nature of the optical beams to derive convenient field evolution equations in coordinate frames moving along Snell's refraction and reflection axes. Through numerical simulations, the self-accelerating dynamics of the Airy-like refracted and reflected beams are observed. Of special interest are the cases of critical incidence at Brewster and total-internal-reflection (TIR) angles. In the former case, we find that the reflected beam achieves self-healing, despite the severe suppression of a part of its spectrum, while, in the latter case, the beam remains nearly unaffected except for the Goos-H?nchen shift. The self-accelerating quality persists even if the beam is trapped by multiple TIRs inside a dielectric film. The grazing incidence of an Airy beam at the interface between two media with close refractive indices is also investigated, revealing that the interface can act as a filter depending on the beam scale and tilt. We finally consider reverse refraction and perfect imaging of an Airy beam into a left-handed medium.