From the authors of manuscript LF14494:
When a reflective object is pushed by a pulse of light, various types of mechanical waves are launched from the illuminated surface. In terms of decreasing amplitude, a high-intensity laser pulse gives rise to the following: ablation-induced waves (AIWs) resulting from material recoil, thermoelastic waves (TEWs) caused by light absorption and the subsequent thermal expansion, and the ubiquitous, but weakest, light-pressure-induced elastic waves (LIWs) emanating solely from the linear momentum transfer during the photon recoil. Even though the macroscopic motion of the object is the superposition of all these waves, only AIWs and LIWs are capable of displacing the object’s center of mass. Until now, LIWs were indiscernible from the dominating AIWs and TEWs. However, we have succeeded, for the first time, in detecting LIW by striking a defocused laser pulse with a fluence of 1 J/cm2 on the front surface of a 99.999% ultra-high-reflectivity mirror. Its reverberations, causing picometer-large displacements of the mirror’s rear facet, were observed with a calibrated piezoelectric sensor. Again, the light heating had to be suppressed, as was the case over a century ago, when the radiation pressure was experimentally validated with a delicate vane, similar to a light mill.
