Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 597 for “"Band gap"”.
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On-chip silicon based photonic structures : photonic band gap and quasi-photonic band gap materials
… silicon based photonic structures, photonic band gap (PBG) and quasi-photonic band gap (QPX) structures, which are based on high refractive index contrast dielectric layers and CMOS compatibility. We developed a new type of silicon waveguide - Photonic Crystal (PC) cladding waveguide is …
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Exploring for new photonic band gap structures
In the infinite set of possible photonic band gap structures there are no simple rules to serve as a guide in the search for optimal designs. The existence and characteristics of photonic band gaps depend on such factors as dielectric contrast, volume fraction, symmetry and connectivity of the …
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Návrh nízkošumové Band Gap reference v BCD procesu
… jednotlivá zapojení a shrnuty parametry výsledné band-gap reference.
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Experimental study of photonic band gap accelerator structures
… on a novel accelerator concept using a photonic bandgap (PBG) structure. Major advances in higher order mode (HOM) damping are required for the next generation of TeV linear colliders. In this work, PBG HOMs are studied theoretically and experimentally for the first time. PBG HOMs are shown in …
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Electromagnetic field computation and photonic band gap devices
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.
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Novel photonic band gap structures for accelerator applications
… experimental demonstration of the first photonic band gap (PBG) accelerator at 17.140 GHz. A photonic band gap structure is a one-, two- or three-dimensional periodic metallic and/or dielectric system (for example, of rods), which acts like a filter, reflecting rf fields in some frequency range …
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Wide band-gap nanowires for light emitting diodes
Wide band-gap nanowires composed of GaN and ZnO are promising materials for unique designs and potential efficiency improvement of light emitting diodes (LEDs) for solid state lighting. The large surface-to-volume ratio of nanowires provides facile strain-relaxation such that nanowires can be grown …
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A 250 GHz photonic band gap gyrotron amplifier
… a 8.9 T magnetic field. The instantaneous -3 dB bandwidth of the amplifier at peak gain is 0.4 GHz. A peak output power of 45 W has been measured. The output power is not saturated but is limited by the 7.5 mW of available input power. The amplifier can be tuned for operation from 245- 256 GHz. …
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The fabrication of 3-D photonic band gap structures
Thesis (Elec. E.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1997.
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Synthesis of electromagnetic modes in photonic band gap fibers
… TEo0, and TE02 for transmission in photonic band gap fibers at near infrared wavelengths. We measure the propagation losses of the HE11 and TE01 modes both inside and outside the band gap of the fiber, and show that the TE01 is indeed the lowest loss mode, and is less lossy and has a much …
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Experimental studies of hybrid photonic band gap accelerator structures
… the first high power tests of a hybrid photonic band gap (PBG) accelerator structure. PBG structures can support a single electromagnetic mode, thus damping higher-order modes (HOMs) generated by wakefields. We have designed, built and successfully tested a 17.14 GHz hybrid PBG (HPBG) structure …
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Investigation of new semiconductor materials for wide band-gap devices
… the compositional and optical properties of wide bandgap III-nitride and gallium oxide semiconductor materials using scanning electron microscopy techniques. The primarily used techniques used here were wavelength dispersive X-ray spectroscopy (WDX) and cathodoluminescence (CL) with other electron …
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Optically Controlled High Power High Speed Wide Band Gap Devices
… over the past few years in the areas of wide bandgap power electronics for high speed, high power and high efficiency switches which enable innovative approaches to compact pulse power system design and implementation. In the area of high speed pulse technology, optical techniques are clearly …
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Band Gap Engineering Of Titania Systems Purposed For Photocatalytic Activity
… form, titania (tio2) has been found to exhibit a band gap nearing 3.2 ev. If titania is to become a viable alternative to other contemporary photoactive materials exhibiting band gaps better suited for the solar spectrum, then the band gap must be subsequently reduced. To lower the energy needed …
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Photonic band gap structures for superconducting radio-frequency particle accelerators
… accelerating cavity with a photonic band gap (PBG) coupler cell. The structure serves as a building block for superconducting radio-frequency (SRF) electron accelerators. It has five accelerating cells: four cells of elliptical shape, commonly used for SRF cavities, and one PBG cell …
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Tunable micro-cavities in photonic band-gap yarns and optical fibers
… derive from their multilayer dielectric photonic band-gap structure that exhibits omnidirectional reflectivity. The theoretical tools needed to design, analyze and optimize such structures are introduced. We show that defect layers in these otherwise periodic structures act as optical …
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Wideband Electromagnetic Band Gap (EBG) Structures, Analysis and Applications to Antennas
In broadband antenna applications, the antenna's cavity is usually loaded with absorbers to eliminate the backward radiation, but in doing so the radiation efficiency of the antenna is decreased. To enhance the radiation efficiency of the antennas EBG structures are used, but they operate over a …
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Fabrication of ceramic layer-by-layer infrared wavelength photonic band gap crystals
<p>Photonic band gap (PBG) crystals, also known as photonic crystals, are periodic dielectric structures which form a photonic band gap that prohibit the propagation of electromagnetic (EM) waves of certain frequencies at any incident angles. Photonic crystals have several potential applications …
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