Photons, Magnons and Quantum Technologies – fs pump-probe experiment: spatially and temporally resolved Kerr effect

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This time-resolved Kerr effect device (pump-probe) allows a measurement of the three dynamic components of the magnetization over a 12ns window, under field and cold. It is coupled to a polarized imaging device which allows to visualize pump and probe tasks and to observe the magnetic domains by Kerr effect.

Ti:Sapphire MIRA laser pumped by a Verdi 10W (Coherent), repetition rate 76 MHz, pulse width at sample 200fs
4ns Newport delay line tripled in 12ns
Modulation of the pump and probe beams
Objective mounted on a 300x300x300µm PiezoConcept 3-axis stage
Detection by a diode bridge whose amplified difference signal is sent to a synchronous detection Signal Recovery 7270 : detectable   polarization rotation 0.1 µrad
Quasi-static imaging using an Andor Clara CCD camera with brightness intensifier, with the possibility of external triggering of the image acquisition. It is also possible to perform micro-spectroscopy experiments by selecting the signal from a part of the image and analyzing it in a spectrometer

Sample cooled by contact in an Oxford Microstat BT HiRes II pillar cryostat (4-300 K)

Magnetic fields perpendicular to the plane :

  • electromagnet delivering up to 60mT
  • superconducting coil delivering up to 6T

Planar magnetic fields :

  • air-cooled CAYLAR rotating dipole delivering up to 500mT
  • in-house solenoid delivering up to 50mT

This device is used for example to study the dynamics of magnetization induced by optical pulses, or acoustic wave trains:

Figure : a) Shihab et al., APL ’15 Time-resolved Kerr effect measured on a GaMnAsP thin film, (b) [P. Kuszeswki PhD Mapping of the deformation induced by a surface acoustic wave fsaw=452MHz emitted by a transducer (IDT), and photograph of the sample indicating the probed area.


  • Catherine Gourdon : catherine.gourdon(at)
  • Laura Thevenard : Laura.Thevenard(at)