Tsu-Wei Nee

• Neopola Optical Analysis, U.S.A.

Polarimetric imaging of Stokes vector (I, Q, U, V) can provide independent signatures of polarization and depolarization of biological tissues and cells. Using a Stokes digital imaging system, we measured the Stokes vector images of tissue samples from sections of rat livers. The derived Mueller matrix elements can quantitatively provide five-signa...

The photon-scattering imaging data of Liposyn II intravenous emulsion solution samples of different concentrations and different thicknesses is reported and analyzed. The scattering Mueller matrix element m11 data shows that the maximum number of multi-photon scatterings is an increasing function of concentration and sample thickness.

High Resolution transmission electron microscopy (HRTEM) and electroreflectance (ER) were used to explain the role of point defects in the molecular beam epitaxy (MBE) grown PIN structure containing five coupled (50Å/28Å) GaAs/AlxGa1−xAs quantum wells with x = 0.25. The ER data were taken at 300K and 77K for energies from 1.4 to 2.1 eV from which s...

We have measured the photovoltaic spectra at 300K for a PIN GaAs/AlGaAs structure containing five coupled wells (50A/28A) grown by molecular beam epitaxy (MBE). The spectra were obtained in the energy range from 1.40 eV to 1.60 eV. This is the region in which optical transitions between the sub-band valence and conduction states are possible. Five...

Electroreflectance (ER) measurements were made on GaAs/AxGal-x As coupled quantum wells at room temperature and at 77K. The close coupling of the narrow (28.3 A) barriers resulted in splitting of the hole and electron subband levels which was observed at both temperatures. As a first approximation, the confining potential was assumed to be due to t...

Tissue is optically anisotropic and highly photon-scattering medium. It has long been treated as optically diffusive medium in bio-medical applications. The diffusion equation of isotropic photon-density wave (PDW) was widely applied to interpret the data of reflectance spectroscopy and biomedical imaging experiments. In our recent transmission Sto...

Analytic formulas are derived for the Jones matrix and the Mueller matrix for dipole scattering by an ellipsoid and by a system of ellipsoids with totally random orientation. The scattering Mueller matrix by an ellipsoid as a function of ellipsoid orientation was simulated and showed complicated structure. The average Jones matrix for an ensemble o...

Tissues are optically anisotropic and highly photon scattering media. By using a simple ellipsoid model of bio-molecules with anisotropic distribution and using an effective mean-field theory, the principal anisotropic index of refraction nj(omega) and absorption extinction coefficient Kaj(omega), (j = x,y,z) are derived. The scattering extinction...

The depolarization property of a biomedium with anisotropic biomolecule optical scattering is investigated theoretically. By using a simple ellipsoid model of a single biomolecule, the scattering fields and Mueller matrices are derived from fundamental electromagnetism theory. The biomedium is modeled as a system of uncorrelated anisotropic molecul...

The bio-media are made of anisotropic molecules. Using a simple ellipsoid model, the scattering of bio-medium with anisotropic bio-molecule is investigated theoretically. The scattering fields and Mueller matrices are derived from fundamental electromagnetism theory. The bio-medium is modeled as a system of non-correlated anisotropic molecules. Bas...

Light depolarization due to multiple scattering in tissue is an interesting bio-medical issue. The bio-tissue is made of anisotropic molecules. Using a simple ellipsoid model, the polarization property of single anisotropic bio-molecule has been investigated theoretically. We extend this theory to a bio-tissue that is modeled as a system of non-cor...

An isotropic medium can consist of a system of spherical particles as well as anisotropic particles with perfectly random orientation. Even though the scattering particle is spherical, the anisotropic geometry of the incident and scattering direction can cause polarization in the scattering beam. For a system of randomly oriented anisotropic partic...

The full polarization properties of anisotropic biomolecule optical scattering are investigated theoretically. By using a simple ellipsoid model of a single biomolecule, the scattering fields and Mueller matrices are derived from fundamental electromagnetism theory. The energy of scattered photons is not necessarily equal to that of the incident la...

The polarization of diffraction by a sawtooth reflection grating has been previously measured with fixed in and out directions while the grating was turned. The measured polarization and depolarization can provide more information about grating diffraction. The efficiency and polarization of diffraction by the two sawtooth facets are simulated base...

The full polarization property of holographic volume-grating enhanced second-harmonic diffraction (SHD) is investigated theoretically. The nonlinear coefficient is derived from a simple atomic model of the material. By using a simple volume-grating model, the SHD fields and Mueller matrices are first derived. The SHD phase-mismatching effect for a...

Diffraction angles, diffraction efficiency and polarization of diffraction by a reflection grating were measured by a null ellipsometer at a wavelength of 632.8 nm. The grating is too rough to be measured by a stylus profiler or an interferometric profiler. The measured diffraction angles follow the grating equation very well and can be used to pre...

A Mueller matrix for scattering by a rough plane surface of a glass hemisphere was simulated by using a micro-facet model. The algorithms are formulated in vector representation in terms of the input and output directions. The single-facet scattering simulation used the results of the Kirchhoff integral for medium rough surfaces with exponential he...

The full polarization property of volume holographic grating diffraction is investigated theoretically. With a simple volume grating model, the diffracted fields and Mueller matrices are first derived from Maxwell’s equations by using the Green’s function algorithms. The formalism is derived for the general case that the diffraction beam and the gr...

The transmittance, ellipsometric parameters, and depolarization of transmission, diffraction, and reflection of two volume holographic gratings (VHGs) are measured at a wavelength of 632.8 nm. The measured data are in good agreement with the theoretical simulated results, which demonstrated the correlation between the diffraction strength and the p...

We propose an ultrafast holographic Stokesmeter using a volume holographic substrate with two sets of two orthogonal gratings to identify all four Stokes parameters of the input beam. We derive the Mueller matrix of the proposed architecture and determine the constraints necessary for reconstructing the complete Stokes vector. The speed of this dev...

Polarization of both Reflection and transmission scatterings by a rough plane surface of a glass hemisphere with a smooth spherical surface were measured. Null ellipsometry was used to measure the ellipsometric parameters and depolarization. Linear polarization, circular polarization, and principal Mueller matrix were obtained from the above measur...

The full polarization property of a holographic volume grating sample is investigated both theoretically and experimentally. There exists strong interaction between the transmitted and diffracted beams due to the grating diffraction of orders m=-1 and 1. Based upon a volume grating mode, the diffracted fields and Mueller matrices of the interacting...

We show that the Stokes parameters of incident light can be determined through the mathematical analysis of only the intensities of the beams produced by multiple, super-imposed holographic gratings. Experimental verification of the theory of polarization dependence of a thick grating is also presented.

Principal Mueller matrices of scattering by a rough paint surface are measured. Null ellipsometry is used to measure the ellipsometric parameters and depolarization of scattering with small depolarization ( 0.2), and all other polarization characteristics are derived from the principal Mueller matrix. Scattering is measured at fixed angle (2K) betw...

Reflectance R, ellipsometric parameters (ψ, Δ), depolarizations D, and cross-polarized depolarization Dv of specular reflection, and scattering by a rough stainless steel surface are measured using a null ellipsometer. The three polarization elements (Px, Py, Pz) of a principal Mueller matrix are obtained from D, ψ, and Δ. The measured ψ and Δ of s...

Transmission scattering from medium to air was used to measure the slope distribution of the rough plane surface of a transparent glass hemisphere. A facet model successfully explained the measured results of refraction, scattering, and polarization: Transmission scattering existed for incident angles greater than the critical angle, all measured c...

A circular polarization sensor is feasible to detect a sea-skimming cruise missile in a solar corridor. We report the simulated performance results of a shipboard medium-wave infrared (MWIR) circular polarization sensor to detect a sea-skimming missile above rough sea surface. The sensor observed total and circular target and sea clutter signals at...

Ellipsometric parameters, depolarization and directional reflectance of reflection and scattering by a rough stainless steel surface are measured. Linear and circular polarizations, and principal Mueller matrix can be obtained from the above quantities. Measurements were made at fixed incident and detection directions and variable sample's orientat...

Based upon known surface optical properties, we develop a model to calculate and analyze the linear and circular polarization signatures for targets of known geometric shapes. The linear and circular polarization radiation (emission and reflection) generated from the target surfaces are studied in two model surface structures: metallic and non-meta...

Based upon known surface optical properties, we develop a model to calculate and analyze the linear and circular polarization signatures for targets of known geometric shapes. The linear and circular polarization radiation (emission and reflection) generated from the target surfaces are studied in two model surface structures: metallic and non-meta...

Optical reflectance of YBa2Cu3O7-d thin films grown by laser ablation is measured within photon energies of 0.1 eV to 3.5 eV at room temperature. The spectra can be fit congruently with the anisotropic dielectric constants which take account of the intraband free carrier transition and interband transition. The anisotropic plasma frequencies are si...

Based upon the published results of YBa 2 Cu 3 O 7 single‐crystal reflectance spectra measured at room temperature, the empirical anisotropic spectral density functions and quasidielectric functions ϵ 1j +iϵ 2j [j=a,b,c] are determined in the 0.05 to 6 eV spectral range. These functions are an excellent fit to the reflectance spectra of samples in...

The Greens-function approach to transient-hot-electron transport of Xing and Ting [Phys. Rev. B 35, 3971 (1987)] is applied to a GaAs/AlxGa1-xAs heterojunction. Scattering mechanisms, such as remote and background ionized impurity scattering as well as acoustic (via deformation potential and piezoelectric coupling) and polar-optical-phonon contribu...

The grazing incidence x‐ray reflectivity is a nondestructive and sensitive technique for probing the depth profile of electron density in layered structures. This method has been utilized in the soft x‐ray regime to determine the roughness of interfaces, and the epilayer thickness in In x Ga 1-x As/InP and In x Ga 1-x As/GaAs heterostructures, for...

The optical spectra of a molecular‐beam‐epitaxially grown In 0.53 Ga 0.47 As epilayer lattice‐matched on a (100) InP substrate are measured in the visible and infrared regions. The transmittance, reflectance, and their wavelength derivatives (wavelength‐modulation spectra) are measured at room temperature. The spectra were analyzed by a theoretical...

We present the infrared wavelength-modulation spectra of molecular-beam-epitaxy- (MBE) and liquid-phase-epitaxy- (LPE) grown Ini_xGaxAs (0.45 < x < 0.50) epilayers on (100) InP substrates. The transmittance, reflectance, and their wavelength derivatives are measured in the neighborhood of the band gap at room temperature. The dependence of band gap...

Extended x-ray absorption fine structure has been measured in an In0.53Ga0.47As compound grown by liquid-phase epitaxy. The fluorescence measurement technique was used so as to preserve the integrity of the as-grown sample. Results indicate that the virtual crystal approximation is invalid in this system, and that the structure contains significant...

Using the Green's-function approach to steady-state nonlinear transport recently developed for an interacting system of electrons, impurities, and phonons, we obtain, in the linear approximation, a generalized Langevin equation for the current operator. From this equation, the time-dependent current, the current fluctuation, the noise associated wi...

The enhanced DC power absorption due to interfacial irregularities in a two-dimensional electron gas field effect transistor (TEGFET) device is calculated and analyzed in a simple model. Quantitatively, the electronic population and intrinsic scattering play important roles in the determination of this enhanced power.

The energy gap of CuInS2 single crystals grown by chemical vapor transport (CVT) and travelling heater method (THM), and thin films prepared by three source evaporation has been studied experimentally using WMR measurements at room temperature. Our results show that better stoichiometry samples of CuInS2 has direct energy gap at 1.535±0.005 eV. The...

The intersubband resonance absorption enhanced by the insulator-semiconductor interfacial irregularities in a metal-insulator-semiconductor system is investigated theoretically. The line shape of absorption spectrum is calculated microscopically. It is shown that the perpendicular excitation can be effectively generated by electric fields parallel...

We present the calculated results for the qualitative and quantitative analysis of the intersubband resonance absorption enhanced by the insulator-semiconductor interfacial irregularities in a metal-insulator-semiconductor system. It shows that the spectral profiles depend strongly on the electronic population distributions of the two subbands invo...

Interaction of germanium with mode-locked Nd:glass laser has been studied, both experimentally [1–3] and theoretically [4], in the past. In one experiment, an intense picosecond pulse creates a dense electron-hole plasma in a thin Ge slab and the interaction region is probed by measuring the transmission of a weak pulse delayed with respect to the...

The strong transient optical absorption in n‐InSb Raman spin‐flip laser device at 2 °K was interpreted due to the intense laser‐generated hot conduction electrons. We present the microscopic theoretical calculation for this nonlinear and nonequilibrium optical effect. By assuming the time‐dependent functions for electronic temperature and Fermi ene...

The electroosmosis effect in electrophoresis experiments has been investigated theoretically using multi-component fluid dynamics. The ionic fluid shearing stress effects and correct boundary conditions have been taken into consideration in order to obtain the solutions of the component fluid velocity profiles. Several model problems with different...

At high-power densities (>~ 2 MW/cm2) the temporal dependence of transmitted 10.6-mum pulses in InSb shows strong pump-depletion effects. The phenomena are on a 30-nsec time scale and are interpreted as due to hot-electronic kinetics and electron-hole excitation processes. A model calculation employing rate constants from independent measurements r...

The contributions of local field and dielectric friction to the electrophoretic mobility in an electrophoresis system are calculated for the simple model of spherical ions. These effects are important in a fluid with a large dielectric constant.

Electrophoresis has contributed significantly to the methodology of biological sciences, and shows the potential for large scale fractionation of a wide range of medically important substances, including living cells. Gravity plays an important role in the electrophoretic process, and hence the importance of the NASA effort to develop a zero-gravit...

The fundamental formulas of electrophoresis are derived microscopically and applied to the problem of isotachophoresis. A simple physical model of the isotachophoresis front is proposed. The front motion and structure are studied in the simplified case without convection, diffusion and non-electric external forces. This is an essential improvement...

The effect of small O☒H bond vibration on the bending potential of an H2O molecule is derived. It changes the equilibrium bending angle and is experimentally observable.

The unique coherence properties displayed by superconductors has often lead to the observation that the entire system behaves like a single quantum particle of mass 2m and charge 2e. In this paper we establish the conditions under which this macroscopic quantum assertion is valid within the framework of the microscopic theory of superconductivity.

The theory of dielectric relaxation in a model polar liquid is developed and applied to experimental data. The model is a spherical Onsager cavity, with a uniform dielectric background described by the high frequency limit ϵ∞ and containing a permanent point dipole. The dipole moment undergoes rotational Brownian motion in the cavity. Dielectric fr...

We present here a detailed theory of electronic surface quantum states in a low magnetic field, as well as of their effects on the microwave surface impedance. A marked oscillatory structure in the microwave absorption as a function of magnetic field has been carefully observed by Khaikin and by Koch et al. The quantized magnetic surface levels are...

Recent absolute measurements of many helium excitation functions at low pressure and of the singlet and triplet D functions at several pressures have allowed an extension and upgrading of the multiple-state-transfer process. Atoms excited to an n¹P level are converted to a mixed singlet–triplet F state by an atomic collision. Low-lying singlet and...