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Université de Fribourg

Quantitative study of optical pumping in the presence of spin-exchange relaxation

Shi, Yongqi ; Scholtes, Theo ; Grujić, Zoran D. ; Lebedev, Victor ; Dolgovskiy, Vladimir ; Weis, Antoine

In: Physical Review A, 2018, vol. 97, no. 1, p. 013419

We have performed quantitative measurements of the variation of the on-resonance absorption coefficients κ0 of the four hyperfine components of the Cs D1 transition as a function of laser power P, for pumping with linearly and with circularly polarized light. Sublevel populations derived from rate equations assuming isotropic population relaxation (at a rate γ1) yield algebraic κ0(P)...

Université de Fribourg

Orientational dependence of optically detected magnetic resonance signals in laser-driven atomic magnetometers

Colombo, Simone ; Dolgovskiy, Vladimir ; Scholtes, Theo ; Grujić, Zoran D. ; Lebedev, Victor ; Weis, Antoine

In: Applied Physics B, 2017, vol. 123, no. 1, p. 35

We have investigated the dependence of lock-in-demodulated Mx-magnetometer signals on the orientation of the static magnetic field B0 of interest. Magnetic resonance spectra for 2400 discrete orientations of B0 covering a 4π solid angle have been recorded by a PC-controlled steering and data acquisition system. Off-line fits by previously derived lineshape functions allow us to extract the...

Université de Fribourg

A magnetic source imaging camera

Dolgovskiy, Vladimir ; Fescenko, Ilja ; Sekiguchi, N. ; Colombo, Simone ; Lebedev, Victor ; Zhang, J. ; Weis, Antoine

In: Applied Physics Letters, 2016, vol. 109, no. 2, p. 023505

We describe a magnetic source imaging camera (MSIC) allowing a direct dynamic visualization of the two-dimensional spatial distribution of the individual components Bx(x,y), By(x,y) and Bz(x,y) of a magnetic field. The field patterns allow—in principle— a reconstruction of the distribution of sources that produce the field B→ by inverse problem analysis. We compare experimentally...

Université de Fribourg

M(H) dependence and size distribution of SPIONs measured by atomic magnetometry

Colombo, Simone ; Lebedev, Victor ; Grujic, Zoran Dragan ; Dolgovskiy, Vladimir ; Weis, Antoine

In: International Journal on Magnetic Particle Imaging, 2016, vol. 2, no. 1, p. -

We demonstrate that the quasistatic recording of the magnetic excitation function M(H) of superparamagnetic iron oxide magnetic nanoparticle (SPION) suspensions by an atomic magnetometer allows a precision determination of the sample’s iron mass contentmFe and the particle size distribution.

Université de Fribourg

MPS and ACS with an atomic magnetometer

Colombo, Simone ; Lebedev, Victor ; Grujic, Zoran Dragan ; Dolgovskiy, Vladimir ; Weis, Antoine

In: International Journal on Magnetic Particle Imaging, 2016, vol. 2, no. 1, p. -

We show that a single atomic magnetometer in a magnetically unshielded environment can be used to perform magnetic particle spectroscopy (MPS) and AC susceptometry (ACS) on liquid-suspended magnetic nanoparticles. We demonstrate methods allowing a simultaneous recording of M(H) and dM/dH(H) dependences of samples containing down to 1 μg of iron. Our results pave the way towards an atomic...

Université de Fribourg

A quantitative study of particle size effects in the magnetorelaxometry of magnetic nanoparticles using atomic magnetometry

Dolgovskiy, Vladimir ; Lebedev, Victor ; Colombo, Simone ; Weis, Antoine ; Michen, Benjamin ; Ackermann-Hirschi, Liliane ; Petri-Fink, Alke

In: Journal of Magnetism and Magnetic Materials, 2015, vol. 379, p. 137–150

The discrimination of immobilised superparamagnetic iron oxide nanoparticles (SPIONs) against SPIONs in fluid environments via their magnetic relaxation behaviour is a powerful tool for bio-medical imaging. Here we demonstrate that a gradiometer of laser-pumped atomic magnetometers can be used to record accurate time series of the relaxing magnetic field produced by pre-polarised SPIONs. We have...

Université de Neuchâtel

Ultra-stable microwave generation with a diode-pumped solid-state laser in the 1.5-µm range

Dolgovskiy, Vladimir ; Schilt, Stéphane ; Bucalovic, Nikola ; Di Domenico, Gianni ; Grop, Serge ; Dubois, Benoît ; Giordano, Vincent ; Südmeyer, Thomas

In: Applied Physics B : Lasers and optics, 2014, vol. 116, no. 3, p. 593-601

We demonstrate the first ultra-stable microwave generation based on a 1.5-µm diode-pumped solid-state laser (DPSSL) frequency comb. Our system relies on optical-to-microwave frequency division from a planar-waveguide external cavity laser referenced to an ultra-stable Fabry–Perot cavity. The evaluation of the microwave signal at ~10 GHz uses the transportable ultra-low-instability signal...

Université de Neuchâtel

All-optical microwave generation using frequency combs

Dolgovskiy, Vladimir ; Südmeyer, Thomas (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2012.

Optical frequency combs from modelocked femtosecond lasers provide a direct, phase-coherent link between the radio frequency and optical domains. This thesis describes the development and realization of an ultra-stable microwave oscillator based on optical-to-microwave frequency transfer using two different optical frequency comb technologies. An optical reference oscillator is realized...

Université de Neuchâtel

Noise properties of an optical frequency comb from a SESAM-modelocked 1.5 µm solid-state laser stabilized to the 10 -13 level

Schilt, Stéphane ; Dolgovskiy, Vladimir ; Bucalovic, Nikola ; Schori, Christian ; Stumpf, Max C. ; Di Domenico, Gianni ; Pekarek, Selina ; Oehler, Andreas E. H. ; Südmeyer, Thomas ; Keller, Ursula ; Thomann, Pierre

In: Applied Physics B : Lasers and optics, 2012, vol. 109, no. 3, p. 391-402

We present a detailed investigation of the noise properties of an optical frequency comb generated from a femtosecond diode-pumped solid-state laser operating in the 1.5-μm spectral region. The stabilization of the passively mode-locked Er:Yb:glass laser oscillator, referred to as ERGO, is achieved using pump power modulation for the control of the carrier envelope offset (CEO) frequency and by...