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Radio frequency resonator for feeding ion trap
Jedlička, Petr ; Pham, Minh Tuan ; Čížek, Martin ; Pavelka, Jan ; Lešundák, Adam ; Hucl, Václav ; Hrabina, Jan ; Řeřucha, Šimon ; Lazar, Josef ; Číp, Ondřej
Two versions of resonators were designed and manufactured - asymmetric and symmetric.\nThe resonator consists of a coil and capacity of ion trap which makes parallel resonant circuit.\nEnergy is supplied to the resonator through the coupling inductance. Resonator assembly was equipped with outputs for monitoring high-frequency voltage. Both versions have been tuned and tested.\n\n
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A pair of phase-synchronized semiconductor lasers for length metrology
Hucl, Václav ; Holá, Miroslava ; Čížek, Martin ; Řeřucha, Šimon ; Pham, Minh Tuan ; Pravdová, Lenka ; Lazar, Josef ; Číp, Ondřej
Semiconductor lasers are increasingly widespread in areas that have been so far dominated by He-Ne lasers. One of such areas is the length metrology, where He-Ne laser operating at 633nm wavelength is still a traditional source of coherent light for laser interferometers distance measuring. The advantages of semiconductor lasers compared with He-Ne laser are greater optical power and a significantly wider range of wavelength tuning without mode jumps. Another advantage is the possibility of frequency modulation of wavelength of the laser diode by directly changing the injection current. The benefits predetermine these laser diodes for the realization of dual-frequency laser sources for heterodyne interferometry. In this case, using a phase-locked loop technique the optical frequency of a laser diode is locked to the optical frequency of another laser diode with a certain frequency offset in the MHz order. In our contribution we present utilization of DBR laser diodes in implementing a dual-frequency laser source for laser interferometry with heterodyne detection.\n
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Phase coherent transfer of stable optical frequency for sensory networks
Čížek, Martin ; Pravdová, Lenka ; Hucl, Václav ; Řeřucha, Šimon ; Hrabina, Jan ; Mikel, Břetislav ; Lazar, Josef ; Číp, Ondřej
Using long-haul optical fiber links for phase coherent transfers of stable optical frequencies has been developed by metrological laboratories for at least a decade. Present boom of optical fiber sensors puts a demand on transferring this technology from laboratories to industrial practice. A remote calibration of fiber Bragg grating tensometers can be an example. In our contribution we present a 306 km long fiber link between laboratories of ISI in Brno and CESNET in Prague. The line uses a telecom fiber with a dedicated DWDM window at 1540-1546 nm. The setup implements a phase coherent transfer of a laser standard working with 1540.5nm wavelength and a bi-directional transfer of 1PPS timestamps from radiofrequency standards at the both ends of the line. A long-term measurement of transport delay fluctuations and relative stability of the line are discussed.
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Laser cooling of the trapped ions for frequency and time metrology
Číp, Ondřej ; Pham, Minh Tuan ; Čížek, Martin ; Lešundák, Adam ; Hucl, Václav ; Hrabina, Jan ; Řeřucha, Šimon ; Jedlička, Petr ; Lazar, Josef
In the laser cooled trapped ions field current research is oriented to yield isolated ions in their basic state of the motion. The detection of the Doppler cooled iont excitation to its quadrupole transition of the electronic structure gives the opportuniny to stabilize highly coherent lasers of the optical frequency of the hundreds of THz. This way a new standart of the time or optical frequencies called „Optical atomic clock“ can be defined. Institute of the Scientific Instruments in Brno in the cooperation with the Department of the Optics of the Palacky University in Olomouc implemented a unique research infrastructure for laser cooling of 40Ca+ ions and subsequent experiments of the quantum mechanics and spectroscopy in a joint laboratory in Brno. Currently 40Ca+ ions are routinely generated and captured. The Doppler cooling of those ions is performed using dipole transition at a wavelength of the 397 nm. Also detection and spectroscopy of the electronic structure of the ion and the presence of his dark resonances is implemented.\n
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Golden nanoparticle in optical tweezers: influence of shape and orientation on optical trapping
Šiler, Martin ; Brzobohatý, Oto ; Chvátal, Lukáš ; Karásek, Vítězslav ; Paták, Aleš ; Pokorná, Zuzana ; Mika, Filip ; Zemánek, Pavel
Noble metal nanoparticles (NPs) have attracted increased attention in recent years due to various applications of resonant collective oscillations of free electrons excited with light (plasmon resonance). In contrast to bulk metal materials, where this plasmon resonance frequency depends only on the free electron number density, the optical response of gold and silver NPs can be tuned over the visible and near-infrared spectral region by the size and shape of the NP. Precise and remote placement and orientation of NPs inside cells or tissue would provide another degree of control for these applications. A single focused laser beam – optical tweezers – represents the most frequently used arrangement which provides threedimensional (3D) contact-less manipulation with dielectric objects or living cells ranging in size from tens of nanometers to tens of micrometers. It was believed that larger metal NPs behave as tiny mirrors that are pushed by the light beam radiative force along the direction of beam propagation, without a chance to be confined. However, recently several groups have reported successful optical trapping of gold and silver particles as large as 250 nm. We\noffer an explanation based on the fact that metal nanoparticles naturally occur in various nonspherical\nshapes, and their optical properties differ significantly due to changes in localized plasmon excitation.
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Noise to signal transition: work obtained from noise studied by the optical tweezers
Šiler, Martin ; Filip, R. ; Jákl, Petr ; Brzobohatý, Oto ; Zemánek, Pavel
The noise-to-signal transitions are very interesting processes in physics as they might transform environmental noise to useful mechanical effects. In this contribution we introduce the problem of stochastic noise-to-signal transition of overdamped Brownian motion of a particle in the cubic potential. The particle reaches thermal equilibrium with its environment in the quadratic potential which is suddenly swapped to the cubic potential. We predict simultaneous increase of both the displacement and signal-to-noise ratio in the cubic potential for the position linearly powered by temperature of the particle environment. Further, we propose a feasible experimental setup for proof-of-the-principle experiment that uses methods of optical trapping in shaped laser beams providing cubic and quadratic potentials.
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Lenght characterization of a piezoelectric actuator by use of a mode-locked femtosecond laser
Pravdová, Lenka ; Lešundák, Adam ; Šmíd, Radek ; Číp, Ondřej
Modern laser interferometers with high resolution are considered as very precise sensors for length measurement. We assembled a specialized optical resonator using silver mirrors. The femtosecond laser with a repetition frequency of 250 MHz and a central wavelength 1560 nm of supercontinuum is used. Femtosecond laser is stabilized by optical frequency comb technique, ie. the frequency offset fCEO and repetition frequency frep is synchronized by our ultra-stable frequency source - hydrogen maser. The technique of derivative spectroscopy is used for locking the resonance peaks of the resonator component of the supercontinuum. The frequency frep in fine steps in the desired range of values is changed via control electronics. This was achieved by changing the length of the cavity in the order of several hundred of nanometers. Repetition frequency change is carried out so that the entire range of the length of the actuator is tested. Value of the applied voltage is recorded for every measured point of the characteristics. The result is a measured characteristic hysteresis curve of the PZT actuator.
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Frequency stabilization of DBR diode laser working on 633 nm for lenght metrology and spectroscopy
Pham, Minh Tuan ; Hucl, Václav ; Čížek, Martin ; Mikel, Břetislav ; Hrabina, Jan ; Řeřucha, Šimon ; Lazar, Josef ; Číp, Ondřej
Semiconductor lasers are nowadays very convenient and suitable for many applications in field of human activities. Mainly it is thanks to their small size, low cost and high energy efficiency. This work deals with frequency stabilization of DBR diode laser working on 633 nm and the measurements of its noise properties. For this purpose we have chosen DBR diode EYP-DBR-0633 from Eagleyard Photomic. This particular laser diode in temperature range from 6 degrees celsius to 24 degrees Celsius has a tuning range of 0,86 nm, which correspond to change of 650 GHz in optical frequency domain. In this paper we also present methodology and results for frequency noise properties investigation of this laser with unbalanced Mach-Zhender interferometer and 10 m long fibre spool inserted in reference arm.
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Measurement of real-time gigacycle fatigue through real-time interferometry
Lazar, Josef ; Holá, Miroslava ; Hrabina, Jan ; Číp, Ondřej
We present an interferometric method for measurement of strain induced deformation of metal samples in experiments inducing high-cycle fatigue. The motivation is to get real-time information about the deformation of a metal sample under test, its elongation imposed by fast vibrating actuator. Fatigue of materials is a process of degradation of a material due to repeated application of forces which includes nucleation and propagation of cracks and leads to the failure of the component. It may appear in all parts of machines or structures which rotate, vibrate, are repeatedly loaded, are subjected to temperature gradients etc., so statistically, fatigue is implied in about 80% of all industrial failures.
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