Résumé
The glass is a disordered solid that processes distinct dynamical and elastic
properties compared with crystal. How heterogeneous glassy materials can be and
to what extent dynamics is encoded with structure and elasticity are
long-standing puzzles in glass science. In this experiment, we probed the
responses of binary colloidal glasses towards the excitations induced by highly
focused laser pulses. We observed very similar excitation patterns when the
laser was repeated in the linear region; directly proving that the dynamical
heterogeneity is strongly encoded with structure. In the non-linear region, we
identified a non-monotonic dynamical length scale as a function of area
fraction, resulting from the non-monotonic coupling of momentum transfer in
radial and orthogonal directions. Surprisingly, the excitation size and radius
of gyration conformed to a universal scaling relation that covered both linear
and non-linear regions. Our experiments offered a new strategy of actively
probing the response of glassy materials on the microscopic level.