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11.
We propose a new synthesis method for the design of multilayer optical filters with intermediate refractive indices, the step method. This method consists in adding infinitesimally small index steps in the index profile at optimal positions and then reoptimizing the thickness and the refractive index of the layers. Application of the method to the design of an antireflective coating, a low-pass edge filter, and an immersed polarizing beam splitter shows that it provides interesting solutions, even in the absence of a proper starting design. The formalism developed for the method also serves to demonstrate that the optimal filter consists of either homogeneous layers that maximize the effective refractive index contrast, or of graded-index layers. 相似文献
12.
Hervé Dumont Ludvik Svob Dominique Ballutaud Ouri Gorochov 《Journal of Electronic Materials》1994,23(2):239-242
The metalorganic chemical vapor deposition growth of ZnTe has been performed at atmospheric pressure under helium and hydrogen
carrier gases. Epitaxial growth was achieved on GaAs (100) substrates with the combination of diethylzinc and diethyltellurium
as precursors. We have studied the incorporation of carbon and hydrogen in as-grown layers of ZnTe by secondary ion mass spectroscopy
analysis and out-diffusion experiments with different carrier gases and growth temperatures. The amount of carbon and hydrogen
incorporated in the ZnTe layers greatly depends on the nature of the gas considered. Under helium atmosphere, the amount of
carbon and hydrogen incorporated are greater than under H2 with an origin from organometallic precursors. 相似文献
13.
An algorithm is presented which finds the best-fitting pair of constants, in the least squares sense, to a set of scalar data; we call this pair of constants the ‘bimean’ of the data. The relationship of the bimean clustering to the ISODATA clustering algorithm, and its application to image thresholding, are also discussed. 相似文献
14.
Haloacetate analogs of pheromones: Effects on catabolism and electrophysiology inPlutella xylostella
A series of mono-, di-, and trihalogenated acetate analogs of Zl 1–16: Ac were prepared and examined for electrophysiological activity in antennae of males of the diamondback moth,Plutella xylostella. In addition, two potential affinity labels, a diazoacetate (Dza) and a trifluoromethyl ketone (Tfp), were evaluated for EAG activity. The Z11–16Ac showed the highest activity in EAG assays, followed by the fluorinated acetates, but other halo-acetates were essentially inactive. The polar diazoacetate and the trifluoromethyl ketone were also very weak EAG stimulants. The effects of these analogs on the hydrolysis of [3H]Z11–16Ac to [3H]Z11–16OH by antennal esterases was also examined. The three fluorinated acetates showed the greatest activity as inhibitors in competition assays, with rank order F2Ac > F3Ac > FAc > Ac > Cl2Ac > ClAc > Dza > Br2Ac > BrAc > Tfp > I > Cl3Ac > Br3Ac > OH. The relative polarities of the haloacetates, as determined by TLC mobility, are in the order mono- > di- > trihalo, but F, Cl, Br, and I all confer similar polarities within a substitution group. Thus, the steric size appears to be the predominant parameter affecting the interactions of the haloacetate analogs with both receptor and catabolic proteins inP. xylostella males.On leave from Institute of Organic Chemistry, Czechoslovak Academy of Science, Flemingovo namstí 2, 16610, Prague, Czechoslovakia. 相似文献
15.
16.
A technique is described for obtaining the nonlinear interaction between two surface waves propagating in a piezoelectric semiconductor. The coupling between the waves is associated with the transverse electric fields of the surface wave and the carriers in the semiconductor. The effective carrier concentration for the interaction has been altered by forming a surface-depletion region beneath a metal?semiconductor contact. This scheme has been used to produce the convolution of two oppositely travelling acoustic waves in epitaxial gallium arsenide, and it has been found that a strong nonlinearity can be obtained at small acoustic-power levels. 相似文献
17.
Tomas Netolicky Lukas Strizik Ludvik Benes Klara Melanova Stanislav Slang Tomas Wagner 《Journal of the American Ceramic Society》2022,105(5):3391-3402
The nanocrystalline single-phase Er3+-doped Yb3Ga5O12 garnets have been prepared by the sol-gel combustion technique with a crystallite size of ≈30 nm. The presence of Yb3+ in garnet hosts allows their efficient excitation at the ≈977 nm wavelength. The Er3+ doping of Yb3Ga5O12 garnet host results in deep red Er3+: 4F9/2 → 4I15/2 upconversion photoluminescence (UCPL) emission. The dominance of the red UCPL emission over the green Er3+: 4F7/2/2H11/2/4S3/2 → 4I15/2 component was investigated using the measurement of the steady-state and time-dependent Er3+ and Yb3+ emission spectra in combination with the power-dependent UCPL emission intensity. The proposed upconversion mechanism is discussed in terms of the Er3+ → Yb3+ energy back transfer process as well as Yb3+(Er3+) → Er3+ energy transfer and Er3+ ↔ Er3+ cross-relaxation processes. The studied Er3+-doped Yb3Ga5O12 garnet may be utilized as a red upconversion emitting phosphor. 相似文献
18.
19.
We propose to refine the refractive index of the layers composing optical filters while keeping their optical thicknesses constant. Using this technique, one can optimize filters made of quarter-wave layers using conventional optimization techniques, while preserving the possibility to use turning-point monitoring during their fabrication. Application of this method to the design of a dual narrowband filter and a tilted edge filter demonstrates its effectiveness. 相似文献
20.
The design of optical filters relies on powerful computer-assisted methods. Many of these methods are provided by commercial programs, but, in order to adapt and improve them, or to develop new methods, one needs to create his own software. To help people interested in such a process, we decided to release our in-house software, called OpenFilters, under the GNU General Public License, an open-source license. It is programmed in Python and C++, and the graphical user interface is implemented with wxPython. It allows creation of multilayer and graded-index filters and calculation of reflection, transmission, absorption, phase, group delay, group delay dispersion, color, ellipsometric variables, admittance diagram, circle diagram, electric field distribution, and generation of reflection, transmission, and ellipsometric monitoring curves. It also provides the refinement, needle, step, and Fourier transform methods. 相似文献