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Krupka J.,Warsaw University of Technology | Strupinski W.,Institute Of Electronic Materials Technology of Poland
Applied Physics Letters | Year: 2010

Single postdielectric resonators operating on their quasi TE011 modes were used for the measurement of the surface resistance and conductivity of graphene films grown on semi-insulating SiC substrates. With this technique the surface resistance was measured with an uncertainty of ±5% and the conductivity was evaluated with an uncertainty equal to the uncertainty in determining the film thickness. The room temperature conductivity of the graphene films proved to be in the range 5× 106 to 6.4× 106 S/m. © 2010 American Institute of Physics.

Soluch W.,Institute Of Electronic Materials Technology of Poland
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control | Year: 2011

Surface acoustic wave (SAW) synchronous twoport resonators were fabricated and measured on several orientations of the GdCa4O(BO 3)3 crystal. Resonance frequencies, insertion losses, and unloaded quality factors of the resonators, measured at room temperature, were in the ranges of about 432.3 to 437.5 MHz, 3.8 to 6.3 dB, and 6500 to 7500, respectively. The properties of this crystal, such as its lack of a phase transition up to its melting temperature of about 1500°C, a SAW temperature coefficient of frequency of about -80 ppm/°C, and good parameters of the resonators make the crystal attractive for high-temperature sensor applications. © 2006 IEEE.

Chmielewski M.,Institute Of Electronic Materials Technology of Poland | Weglewski W.,Polish Institute of Fundamental Technological Research
Bulletin of the Polish Academy of Sciences: Technical Sciences | Year: 2013

Copper-based composites could be widely used in automotive, electronic or electrical industry due to their very promising thermal properties. In the present paper, Cu-AlN metal matrix composites with ceramic volume fractions between 0.1 and 0.4 were fabricated by hot pressing method in vacuum. Dependence of the coefficient of thermal expansion (CTE) and the thermal conductivity (TC) on the chemical composition of composites has been investigated. The measured values of the thermal expansion coefficient have been compared with the analytical models' predictions. A numerical model based on FEAP 7.5 in 3D space has been used to evaluate the influence of the porosity on the thermal properties (thermal conductivity) of the composite. A fairly good correlation between the FEM results and the experimental measurements has been obtained.

Soluch W.,Institute Of Electronic Materials Technology of Poland
Sensors and Actuators, A: Physical | Year: 2016

Measurement methods and results presented in the title paper were critically analyzed. It was shown that for two-port device, the measured transmission losses are caused not by Rayleigh type surface acoustic wave (SAW) but are the result of interference of the bulk acoustic wave (BAW), generated and detected by interdigital transducers (IDT), and the electrical feedthrough at frequencies higher than that of SAW. Therefore, the measured reflection losses of one-port device, are the results of BAW radiation by the IDT. No resonances exist in both type of devices. © 2015 Elsevier B.V.

Sotor J.,Wroclaw University of Technology | Sobon G.,Wroclaw University of Technology | Grodecki K.,University of Warsaw | Grodecki K.,Institute Of Electronic Materials Technology of Poland | Abramski K.M.,Wroclaw University of Technology
Applied Physics Letters | Year: 2014

In this Letter, we demonstrate a mode-locked Er-doped fiber laser incorporating antimony telluride (Sb2Te3) topological insulator (TI) as a saturable absorber (SA). The laser was capable of generating 270 fs-short soliton pulses at 1560 nm wavelength, which are the shortest solitons generated with a Tl-based saturable absorber so far. In order to form a saturable absorber, a bulk piece of Sb2Te3 was deposited on a side-polished single-mode fiber with the presence of a low refractive index polymer. Such saturable absorber exhibits modulation depth at the level of 6% with less than 3dB of nonsaturable losses. Our study shows that Tl-based saturable absorbers with evanescent field interaction might compete with SAs based on carbon nanomaterials, like graphene or nanotubes. Additionally, thanks to the interaction with the evanescent field, the material is not exposed to high optical power, which allows to avoid optical or thermal damage. © 2014 AIP Publishing LLC.

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