Transient Grating Spectroscopy

 Contact: Alex <>

  • Transient Gratings (TG) is a time-resolved four-wave mixing technique in which two short optical pump pulses are crossed in the sample to crfeate a spatially periodic excitation, whose dynamics is monitored via diffraction of a probe pulse (or a cw beam).
  • We use the TG techniqe to study coherent phonons, thermal transport, ultrafast magnetism and more.
  • A compact and efficient TG setup with optical heterodyning developed in the group  has been replicated by many labs around the world.
  • We also conduct experiments at free electron laser facilities such as FERMI in Trieste, where TG measurementrs in extreme ultraviolet and x-ray ranges have recently become possible. 

(a) Schematic of transient grating experiment;  (b) excitation pettern on the sample; (c) beams crossed in the sample in the transmission geometry; (d) FERMI free welectron laser (highlighted yellow) in Trieste, Italy,  where we conduct transient grating experiments with extreme ultraviolet light (source: FELs of Europe )


Recent work:

Progress with EUV and x-ray transient gratings
Observation of second sound in graphite at temperatures above 100 K
Generation of coherent phonons by femtosecond EUV pulses in a transient grating experiment
Propagation of THz acoustic waves at room temperature
Vibrational dynamics of a two-dimensional micro-granular crystal