Direct excitation of the magnetisation in photon-magnon hybrid systems with an infrared laser pulse

We present experimental results concerning the direct excitation of the magnetisation in a photon-magnon hybrid system composed of a microwave cavity and an embedded yttrium iron garnet (YIG) sphere. An 11 ps ultrafast pulsed laser, with wavelength of 1064 nm outside the YIG transparence window, directly excite the magnon modes. We measure the energy deposited in the Kittel mode of magnetisation by exploiting its coupling to the TE102 mode of the rectangular microwave cavity in the strong coupling regime. Energy collection is performed by a standard rf detection chain reading an antenna matched to the cavity resonance. This technique can prove to be essential in the study of the dynamics of cavity magnon-polaritons, finding application in dark matter axion searches and future magnon based quantum information studies.