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Université de Neuchâtel

Design of atomic clock cavity based on a loop-gap geometry and modified boundary conditions

Ivanov, Anton E ; Affolderbach, Christoph ; Mileti, Gaetano ; Skrivervik, Anja K

In: International Journal of Microwave and Wireless Technologies, 2017, vol. 9, no. 7, p. 1373-1386

In this study, we investigate a concept that can be used to improve the magnetic field homogeneity in a microwave cavity applied in a novel, high-performance atomic frequency standard. We show that by modifying the boundary conditions in the case of a loop-gap geometry, a good improvement of the field homogeneity can be obtained. Such a design demonstrates high potential to improve the frequency...

Université de Neuchâtel

Optically-detected spin-echo method for relaxation times measurements in a Rb atomic vapor

Gharavipour, Mohammadreza ; Affolderbach, Christoph ; Gruet, Florian ; Radojičić, I. S ; Krmpot, A. J ; Jelenković, B. M ; Mileti, Gaetano

In: New Journal of Physics, 2017, vol. 19, no. 063027, p. 1-11

We introduce and demonstrate an experimental method, optically-detected spin-echo (ODSE), to measure ground-state relaxation times of a rubidium (Rb) atomic vapor held in a glass cell with buffer-gas. The work is motivated by our studies on high-performance Rb atomic clocks, where both population and coherence relaxation times ( T1 and T2 , respectively ) of the ‘ clock transition...

Université de Neuchâtel

Interferometric measurements beyond the coherence length of the laser source

Salvadé, Yves ; Przygodda, Frank ; Rohner, Marcel ; Polster, Albert ; Meyer, Yves ; Monnerat, Serge ; Gloriod, Olivier ; Llera, Miguel ; Matthey, Renaud ; Di Francesco, Joab ; Gruet, Florian ; Mileti, Gaetano

In: Optics Express, 2016, vol. 24, no. 19, p. 21729-21743

Interferometric measurements beyond the coherence length of the laser are investigated theoretically and experimentally in this paper. Thanks to a high-bandwidth detection, high-speed digitizers and a fast digital signal processing, we have demonstrated that the limit of the coherence length can be overcome. Theoretically, the maximal measurable displacement is infinite provided that the sampling...

Université de Neuchâtel

Rb-stabilized laser at 1572 nm for CO2 monitoring

Matthey, Renaud ; Moreno, William ; Gruet, Florian ; Brochard, Pierre ; Schilt, Stéphane ; Mileti, Gaetano

In: Journal of Physics: Conference Series, 2016, vol. 723, no. 1, p. 012034

We have developed a compact rubidium-stabilized laser system to serve as optical frequency reference in the 1.55-μm wavelength region, in particular for CO2 monitoring at 1572 nm. The light of a fiber-pigtailed distributed feedback (DFB) laser emitting at 1560 nm is frequency-doubled and locked to a sub-Doppler rubidium transition at 780 nm using a 2-cm long vapor glass cell. Part of...

Université de Neuchâtel

Imaging Microwave and DC Magnetic Fields in a Vapor-Cell Rb Atomic Clock

Affolderbach, Christoph ; Du, Guan-Xiang ; Bandi, Thejesh ; Horsley, Andrew ; Treutlein, Philipp ; Mileti, Gaetano

In: IEEE Transactions on Instrumentation and Measurement, 2015, vol. 64, no. 12, p. 3629-3637

We report on the experimental measurement of the dc and microwave magnetic field distributions inside a recently developed compact magnetron-type microwave cavity mounted inside the physics package of a high-performance vapor-cell atomic frequency standard. Images of the microwave field distribution with sub-100- μm lateral spatial resolution are obtained by pulsed optical-microwave Rabi...

Université de Neuchâtel

Stability limitations from optical detection in Ramsey-type vapour-cell atomic clocks

Kang, Songbai ; Gharavipour, Mohammadreza ; Affolderbach, Christoph ; Mileti, Gaetano

In: Electronics Letters, 2015, vol. 51, no. 22, p. 1767-1769

In today’s state of the art compact vapour-cell atomic clocks relying on the pulsed Ramsey-type interrogation, optical detection noise is a major limitation to the achievable short-term stability. In this communication, the influence of the optical detection time on the clock’s short-term stability is investigated and a new analytical expression is developed to precisely predict the stability...

Université de Neuchâtel

Compact rubidium-stabilized multi-frequency reference source in the 1.55-μm region

Matthey, Renaud ; Gruet, Florian ; Schilt, Stéphane ; Mileti, Gaetano

In: Optics Letters, 2015, vol. 40, no. 11, p. 2576-2579

Combining light modulation and frequency conversion techniques, a compact and simple frequency-stabilized optical frequency comb spanning over 45 nm in the 1.56- μm wavelength region is demonstrated. It benefits from the high-frequency stability achievable from rubidium atomic transitions at 780 nm probed in a saturation absorption scheme, which is transferred to the 1.56- μm spectral region...

Université de Neuchâtel

Self-induced transparency and coherent population trapping of 87Rb vapor in a mode-locked laser

Masuda, Koji ; Affolderbach, Christoph ; Mileti, Gaetano ; Diels, Jean-Claude ; Arissian, Ladan

In: Optics Letters, 2015, vol. 40, no. 9, p. 2146-2149

Simultaneous self-induced transparency and a dark line resonance are observed inside a mode-locked laser. The circulating pulse, tuned to the 795-nm optical resonance of rubidium, has sufficient intensity to create at each passage a population inversion—return to ground state, typical of self-induced transparency. A drop in fluorescence (dark line resonance), is observed as the...

Université de Neuchâtel

Demonstration of a high-performance pulsed optically pumped Rb clock based on a compact magnetron-type microwave cavity

Kang, Songbai ; Gharavipour, Mohammadreza ; Affolderbach, Christoph ; Gruet, Florian ; Mileti, Gaetano

In: Journal of Applied Physics, 2015/117//104510/1-5

We demonstrate a high-performance pulsed optically pumped (POP) Rb vapor-cell clock based on a magnetron-type microwave cavity of only 44 cm3 external volume. Using optical detection, an unprecedented 35% contrast of the Ramsey signal has been obtained. Both the signal-to-noise ratio (of 30 000) and the estimated shot-noise limit of 1.7×10-14τ-1/2 are at...

Université de Neuchâtel

Aging studies on micro-fabricated alkali buffer-gas cells for miniature atomic clocks

Abdullah, Salman ; Affolderbach, Christoph ; Gruet, Florian ; Mileti, Gaetano

In: Applied Physics Letters, 2015/106//163505/1-5

We report an aging study on micro-fabricated alkali vapor cells using neon as a buffer gas. An experimental atomic clock setup is used to measure the cell’s intrinsic frequency, by recording the clock frequency shift at different light intensities and extrapolating to zero intensity. We find a drift of the cell’s intrinsic frequency of (-5.2 ± 0.6) × 10-11/day and quantify...