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The general approach for calculation and analyzing frequency and field impedance dependencies of BAW composite resonator structures with parametrically exited layers is developed. The BAW resonator consisting of two piezoelectric layers was considered. The first dielectric layer was the electric input transducer of the structure and was connected with the source of signal frequency ω. The second one...
We developed a method for studying a tuning fork with nonperfect clamp and coupling between the arms. The model consists of torsion springs linking each beam with the base and a torsion spring linking the beams together. This model allows to consider the case of two different beams to study imperfections. Full determination of motional parameters is presented.
Usually, starting of oscillation in a quartz crystal oscillator requires a resonator's input power in the range of - 20 dBm, but under storage a phenomenon known as Drive Level Dependency (DLD) or Drive Level Sensitivity (DLS) may appear that prevents the starting of oscillation. Several studies performed in the past have shown that at low drive level some quartz resonators may exhibit a large increase...
How the experience shows with a stable production flow and an exact equivalent geometric shape of the blanks, the temperature frequency behaviour of the finished crystals can be different. It is known that the first and the third order coefficient of the temperature frequency curve vary for different manufacturers. This effect looks like a variation of the optimal cut angle for the same specification...
We describe a design for a microfabricated atomic frequency reference with a volume of several cubic millimetres and a power dissipation in the range of tens of milliwatts. It is anticipated that this frequency reference will be capable of achieving a fractional frequency instability below 10−11 at integration times of hours.
The linewidth of CPT atomic resonances observed in a vapor cell are usually limited by optical saturation and collisions due to buffer gas. We have applied here the Ramsey method with optical CPT pulses generated by a phase-locked device. Fringes are then produced giving narrow atomic signals only dependent on interrogation time between the two pulses. The possibility to obtain narrow fringe widths...
In this contribution a new caesium fountain frequency standard at the National Physical laboratory (NPL-CsF1) is described. Procedures for evaluation of the systematic frequency shifts are presented. The NPL-CsF1 has a short-term stability of 1.4 ×10−13 τ −½, predominantly due to the local oscillator phase noise. The accuracy, of 1 part in 1015 is limited by the uncertainty of the frequency shift...
This paper reports a review of the Blackbody Radiation (BBR) shift theory for the Cs atom hyperfine clock transition, together with a measurement of the Blackbody Radiation shift in an atomic cesium fountain.
For a long time, one of the main limitations of cesium atomic fountains has been the cold collision frequency shift [2, 7, 10, 11]. By using a method based on a transfer of population by adiabatic passage (AP) [12, 16, 18] allowing to prepare cold atomic samples with a well defined ratio of atomic density as well as atom number we have a better measurement of this effect. By improving the method we...
The paper addresses an analysis of the transversely varying thickness modes of a piezoelectric resonator affected by a convex anisotropic boundary surface. We show that anisotropy of the boundary surface strongly influences the eigenvibrations and capacitances. The relations to calculate the frequency spectrum, relative amplitudes of vibrations and motional capacitances are derived. A numerical simulation...
A great interest recently shown to crystals from the langasite family is a result of the combination of their unique properties and promising feature for those materials used in resonators, filters, and sensors in many fields of technology. Crystals from this family have very versatile compositions and types, they are produced at many different production facilities, and therefore, they require fast...
The paper is devoted to experimental study of non-linearity of HFF crystal units and its influence on the quartz filter intermodulations. On statistical treatment of the measurement data the regression coefficients linking the crystal parameters non-linearity with the intermodulation level have been defined. The origin of the crystal non-linearity was explored through standard fabrication process...
Electrodes on the surface of an elastic substrate have important effects on the surface acoustic wave (SAW) propagation, and related changes like wave velocity and mode shapes due to the presence of electrodes should be considered in the analysis so the information available to practical applications can be accurate and adequate. Because the essential characteristics of surface acoustic wave propagation...
In this paper we report the method used to dissolve the Langasite and Langatate crystals. Then the characterization of chemical impurities like Al, Fe, Na, Li… incorporated in the crystal during the pooling or coming from strating oxides (La2O3, Ga2O3, Ta2O3 and SiO2) is discussed. Finally, the comparison with the quartz crystal material has been done as well in the IR range as in term of chemical...
This paper presents the low-loss natural single phase unidirectional transducer (NSPUDT) SAW filters, which use SAW propagation direction reversal without the reversal of NSPUDT directivity. In this design the input and output NSPUDTs are placed in parallel acoustic tracks. SAW transmission between these tracks and propagation direction reversal are provided by a double reflection from the inclined...
The general understanding describes the ageing of quartz crystals as a change of the frequency over time for all vibration modes in the same size and direction. In reality, a different ageing behaviour of fundamental mode and overtone modes can be noticed. This effect depends on the blank design and on the electrode design.
Based on Tiersten's analysis [1], an accurate calculation of the coupling coefficient dependence on geometrical dimensions and mass-loading for quartz and langasite monolithic structures was performed [2].
Thermoluminescence spectral characteristics of a Ge-doped quartz crystal show the presence of a temperature-glow peak at 200 EC. This peak is not observable in conventionally grown quartz undoped with Ge. Results have been compared and discussed with the near infrared spectral characteristics of natural and conventionally grown quartz crystals.
Thin films of ZnO have been grown using sol-gel technique. The precursor materials for sol preparation include zinc acetate or zinc nitrate. Characterization was done using optical absorption, ellipsometry, X-ray diffraction, photoluminescence and scanning electron microscopy.
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