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The ultracold atoms served as quantum references is a key part of optical lattice clocks, and the thermal dynamics of the atoms in the optical lattice affects the uncertainty and stability of the lattice clocks. Since the carrier spectrum of clock transition in lattices reflects the thermal dynamics of cold atoms, we can obtain the temperature of atoms by measuring the carrier spectrum in 171Yb optical...
Optical frequency division based on mode-locked laser frequency combs makes possible the coherent transfer of frequency stability from optical systems to electronics. It has enabled a revolution in time keeping and frequency metrology. In this paper we describe progress on new methods for frequency comb generation including whispering-gallery-based microcombs and electro-optical comb generation. Demonstration...
We demonstrate that the use of thick AlN films in Very-High-Frequency (VHF) contour-mode resonators (CMRs) enables a reduction of thermoelastic damping (TED) occurring in the metallic layers sandwiching the AlN film. This technique leads to a large improvement of the device quality factor (Q increase >72%) with respect to thin-film counterparts, resulting into the highest Q ever measured in air...
This work deals with an acquiring system dedicated to the measurement of the resonance frequency and the quality factor of organic piezoelectric resonators. These resonators consist of a free-standing cantilever and its non-released counterpart used to compensate electrical signals that are not due to mechanical behavior. The system uses a capacitive half-bridge with two AC voltages in opposite phases,...
High overtone bulk acoustic wave resonator with (Al-ZnO-Al)/GGG/YIG/Pt structure was theoretically considered, fabricated and experimentally examined for acoustic spin pumping — acoustically driven generation of pure spin current at YIG/Pt interface.
We report our recent progress in the experimental implementing of an all-optical 4He atomic magnetometer being free from the dead-zone effect. A liquid crystal is adopted to constitute a polarization rotator. The light linear polarization vector can be adjusted and ultimately kept perpendicular with respect to the varying ambient magnetic field direction. We then make some further investigations to...
We have performed time-resolved measurements on cesium vapor to measure the dependence of the spin relaxation time on confinement area. Lifetime results obtained for cesium vapor trapped inside capillaries with diameters ranging from 75 μm to 1.4 mm are up to 75% shorter than that obtained within a 4.5 cm chamber.
We reported on a progress toward a CPT-Ramsey clock based on a continuous cold cesium beam. The cesium beam has a high flux of 3 × 1010 atoms/s and a most probable velocity of 7 m/s. Two Raman laser beams are aligned to be orthogonal to the cold atomic beam. The two CPT zones are spatially separated. A CPT resonance is observed with a single interaction zone.
The acceleration sensitivity and its related problem of force-frequency in quartz resonators were studied. We studied the effects of initial nonlinear strains versus the effects of nonlinear elastic constants on the force-frequency problem of quartz resonators subjected to bending forces. We found that for quartz thickness shear resonators subjected to bending, the force frequency effect could be...
We report an optomechanical downmixing measurement method for nanomechanical resonators, which enables the readout of resonance frequencies larger than the bandwidth of the photodetector. We show this method can easily readout the Brownian noise of the device, in which case the performance of the system is not degraded with respect to direct measurement. In the case when the performance is limited...
We propose a nonlinear optical mass sensor based on a suspended monolayer MoS2 nano-optomechanical resonator in all-optical domain. The masses of external particles (such as single influenza virus and HIV virus) landing onto the surface of the MoS2 resonator can be determined directly and accurately via using the nonlinear optical spectroscopy. This mass sensing proposed here may provide a nonlinear...
A novel compact optoelectronic oscillator employing Fabry-Perot (FP) resonator based on travelling-waveguide-type electro-optic (EO) modulator has been proposed and experimentally demonstrated. The EO modulator based FP resonator is used as the optical energy storage and mode selection elements, which can greatly reduce the system complexity by replacing long optical fiber and microwave narrow bandpass...
National Physical Laboratory, India (NPLI) has developed its first Cesium atomic fountain frequency standard (NPLI-CsFl). The indigenously developed fountain frequency standard is now fully operational and its frequency is now being evaluated along with all systematic and statistical uncertainties. Seven frequency evaluation have been conducted to estimate fountain frequency with respect to TAI (International...
In the frame of an optical reference laser system, a frequency-stabilized optical frequency comb was generated from the radiation of a 1560-nm DFB laser, which was frequency-doubled and stabilized to a rubidium transition in a sub-Doppler absorption scheme using a 2-cm long vapor glass cell. A DFB laser emitting at 1572 nm was then offset-locked to an appropriate line of the comb. At 1572 nm, a relative...
Since the discovery of a high piezoelectric response in AlScN by Akiyama and coworkers in 2009, a number of works of other groups confirmed the large increase of piezoelectricity when partially substituting Al cations by Sc cations, as long as the alloy grows in the wurtzite phase. This contribution will present an overview of current knowledge, and compare property data from different authors, including...
A new attempt is presented for detecting a variation in liquid level using a trapped-energy resonator operating in a thickness-shear mode. In contrast to the previously reported method, whole part of the resonator is dipped in a liquid. Rather simple variations of the resonance characteristics on the immersion depth have been observed.
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