Search results for "Resonator"
showing 10 items of 193 documents
Cryogenic 35GHz pulse ENDOR probehead accommodating large sample sizes: Performance and applications.
2009
The construction and performance of a cryogenic 35GHz pulse electron nuclear double resonance (ENDOR) probehead for large samples is presented. The resonator is based on a rectangular TE(102) cavity in which the radio frequency (rf) B(2)-field is generated by a two turn saddle ENDOR coil crossing the resonator along the sample axis with minimal distance to the sample tube. An rf power efficiency factor is used to define the B(2)-field strength per square-root of the transmitted rf power over the frequency range 2-180MHz. The distributions of the microwave B(1)- and E(1)-field, and the rf B(2)-field are investigated by electromagnetic field calculations. All dielectrics, the sample tube, and…
On the exhaust of electromagnetic drive
2016
Recent reports about propulsion without reaction mass have been met on one hand with enthusiasm and on the other hand with some doubts. Namely, closed metal cavities, when fueled with microwaves, have delivered thrust that could eventually maintain satellites on orbits using solar power. However, the measured thrust appears to be without any apparent exhaust. Thus the Law of Action-Reaction seems to have been violated. We consider the possibility that the exhaust is in a form that has so far escaped both experimental detection and theoretical attention. In the thruster's cavity microwaves interfere with each other and invariably some photons will also end up co-propagating with opposite pha…
Experimental demonstration of the physics of resonant cavities
2005
We describe an undergraduate experiment that demonstrates the physics of cavity resonators. A mobile wall lets students alter the position of the nodes, thus changing the mode pattern. The nodal structure is made apparent by placing a metallic plate at different positions inside the cavity. A technique for dielectric characterization also is introduced, which helps students understand the boundary conditions in dielectrics, as well as highlighting the characteristics of fields in cavities.
Reconfigurable dualband antenna module with integrated high voltage charge pump and digital analog converter
2014
Integration of a reconfigurable antenna module for handheld applications employing a set of novel technologies is demonstrated. A low profile dualband hybrid dielectric resonator antenna (DRA) based on glass-ceramics and a tunable matching network (TMN) based on ferroelectric varactors with a maximum biasing of 90V form a reconfigurable antenna module. The control of the antenna module is performed by a 120V CMOS high voltage (HV) charge pump with an 8-bit digital analog (D/A) converter generated from a 3.7V battery. Adaptive impedance matching at the lower band of 1.9 GHz is carried out by the TMN when the dualband antenna is exposed to different operation scenarios. Meanwhile, the upper b…
Quasifractal planar microstrip resonators for microwave circuits
1999
We propose a new shape for microwave planar circuits using the self-similarity of the fractal geometry. This new shape allows the generation of numerous resonant frequencies for this microwave planar resonator due to the surface's encasing. The resonant frequency assessment can be useful for the concept of filters or wide frequency band matching loads as examples, without consuming circuit surface. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 21: 433–436, 1999.
A DRO-based X-band injection-locked amplifier without input non-reciprocal elements
2009
Conventional design of injection-locked amplifiers (ILA's) implies the use of a non-reciprocal (ferrite, usually) element for separating the input signal from the synchronized output signal. In this paper a novel topological structure is proposed which permitted the realization of a wide-band, transmission-type, ILA with no need for separating input-port isolator or preamplifier. The prototype, realized in HMIC technology, while intended only as demonstrator of the newly proposed approach in the design of ILA's, shows quite satisfactory performances at X-band, with a simple, compact and low-cost structure.
Mode cleaning in graphene oxide-doped polymeric whispering gallery mode microresonators
2020
The strategy to incorporate graphene oxide (GO) in a composite material offers significant opportunities to realize compact photonic devices, such as saturable absorbers and polarization selective devices. However, the processing of GO-based composites by direct laser writing, which would afford vast patterning and material flexibility in a single step process, has been little addressed. In this work, we investigated the mechanisms underlying a mode cleaning effect in polymeric whispering gallery mode microresonators containing GO, aiming at the development of on-chip integrable photonic devices. We fabricated the microresonators (cavity loaded Q-factor of 20 000 at 1550 nm) in a single ste…
Development of ultra-fast thulium-doped fiber lasers - Prospects for 2μm-nanophotonics.
2021
Developing highly coherent pulsed sources around the 2 µm wavelengthhas been a particularly dynamic field of research in the last couples of years,due to its numerous applications. In optical telecommunication, the wavelength rangearound 2 µm is one of the most promising solutions to increase the transmission capacitypast the current technological bottleneck. In this context, passively mode-lockedfiber lasers appear as a high potential solution for cheap laser sources, due to their veryhigh coherence and intrinsic compatibility with telecommunication systems.Passively mode-locked fiber lasers at 1,55 µm and their ultrafast dynamics is oneof the specialty of the ICB laboratory, and the aim i…
Metasurfaces for colour printing
2014
We present a theoretical analysis and experimental evidences of metasurfaces based on particle resonators that achieve bright-field colour prints. We created pixels that support individual colours, miniaturized and juxtaposed at the optical diffraction limit. Different strategies are followed to offer the flexibility of using both transmitting and epi (reflective) white light sources. We discuss their potential applications in large-volume colour printing via nanoimprint lithography.
Resonant Tunneling in 2D-Waveguides with Several Resonators
2021
In this chapter, we consider a two-dimensional waveguide that coincides with a strip having \(n+1\) narrows of small diameter \(\varepsilon \). All narrows are of the same shape and are spaced from each other by equal distances. Parts of the waveguide between two neighboring narrows play the role of resonators. The wave function of a free electron satisfies the Dirichlet boundary value problem for the Helmholtz equation in the waveguide. Near a simple eigenvalue of the closed resonator there are n resonant peaks of height close to 1. We let \(\varepsilon \rightarrow 0\) and obtain asymptotic formulas for the resonant energies and for the widths of the resonant peaks at their half-height. Th…