排序方式: 共有8条查询结果,搜索用时 265 毫秒
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A new method is presented to analyze reflection losses of integrated mirrors, taking into account the exact guided mode profile and assuming that this profile remains unchanged up to the reflecting plane. The fraction of the reflected light coupled to one of the guided modes of the output waveguide is calculated, taking into account the mirror reflection coefficient. The influence of both translation and tilt of the reflecting plane is investigated. The method applies for every guided mode and any reflection angles. Numerical calculations are derived for a 90° optical corner mirror 相似文献
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We present a new silicon-on-insulator (SOI) integrated optics structure to be used as an intensity light modulator at 1.3 μm. The device consists of a waveguide Fabry-Perot interferometer. In association with a grating coupler this device could function as a spatial light modulator or a reflective-mode modulator. The Fabry-Perot reflectivity is tuned by free-carrier injection from a forward-biased lateral P+/N-/N+ diode. Consequently, the reflected back guided-mode has an intensity that is a function of the effective index modulation in the central waveguide of the Fabry-Perot. Our numerical simulation reveals that such a structure could function for current densities not exceeding 500 A/cm2 with a cutoff frequency of 100 MHz. This new type of device is compatible with the mature silicon technology and could replace in applications the standard liquid-crystal spatial light modulators or for fiber-to-the-home intensity modulators 相似文献
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Xianqin Meng Guillaume Gomard Ounsi El Daif Emmanuel Drouard Regis Orobtchouk Anne Kaminski Alain Fave Mustapha Lemiti Alexei Abramov Pere Roca i Cabarrocas Christian Seassal 《Solar Energy Materials & Solar Cells》2011
In this paper, we present the integration of an absorbing photonic crystal within a thin-film photovoltaic solar cell. Optical simulations performed on a complete solar cell revealed that patterning the hydrogenated amorphous silicon active layer as a 2D photonic crystal membrane enabled to increase its integrated absorption by 28 % between 300 and 720 nm, comparing to a similar but unpatterned stack. In order to fabricate such promising cells, we developed a high throughput process based on holographic lithography and reactive ion etching. The influences of the parameters taking part in those processes on the obtained patterns are discussed. Optical measurements performed on the resulting “photonized” solar cell structures underline the regularity of the 2D pattern and a significant absorption increase above 550 nm, similarly to what is observed on the simulated absorption spectra. Moreover, our patterned cells are found to be robust with regards to the angle of incidence of the light. 相似文献
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Light coupling into a sub-micrometer-thick waveguide is usually done through a grating coupler. Coupling efficiency is strongly enhanced by addition of a mirror above the grating. This new kind of coupler can be designed to achieve efficiencies as great as 80%. Numerical calculations for a high-angular-spread Gaussian incident beam are compared with experimental results obtained for a standard silicon-on-insulator waveguide. 相似文献
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Martin MJ Benyattou T Orobtchouk R Rooms F Morand A Schanen I Benech P 《Applied optics》2005,44(13):2558-2563
We report the scanning near-field optical microscopy (SNOM) characterization of a 4 x 4 multimode interference (MMI) device working at a wavelength of 1.55 microm and designed for astronomical signal recombination. A comprehensive analysis of the mapped propagating field is presented. We compare SNOM measurements with beam-propagation-method simulations and thus are able to determine the MMI structure's refractive-index contrast and show that the measured value is higher than the expected value. Further investigation allows us to demonstrate that good care must be taken with the refractive-index profile used in simulation when one deals with low-index contrast structures. We show evidence that a step-index contrast is not suitable for adequate simulation of our structure and present a model that permits good agreement between measured and simulated propagating fields. 相似文献
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The fabrication of photoresist gratings is considered. A solution to the problem of `transversal standing waves' is given and appears simple and versatile 相似文献
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The coupling efficiency of grating couplers is derived for a Gaussian incident beam. Its optimum value depends on the beam waist and on the position of a light spot with respect to the coupler edge for given grating parameters. The characteristic coupling length has been experimentally determined for the grating coupler studied. Relative measurements of the coupling efficiency as a function of incident beam characteristics are in good agreement with the numerical results. 相似文献
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