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

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: