Optomechanical backaction processes in a bulk rare-earth doped crystal

Abstract

We investigate a novel hybrid system composed of an ensemble of room temperature rare-earth ions embedded in a bulk crystal, intrinsically coupled to internal strain via the surrounding crystal field. We evidence the generation of a mechanical response under resonant light excitation. Thanks to an ultra-sensitive time-and space-resolved photodeflection setup, we interpret this motion as the sum of two resonant optomechanical backaction processes: a conservative, piezoscopic process induced by the optical excitation of a well-defined electronic configuration, and a dissipative, nonradiative photothermal process related to the phonons generated throughout the atomic population relaxation. Parasitic heating processes, namely off-resonant dissipative contributions, are absent. This work demonstrates an unprecedented level of control of the conservative and dissipative relative parts of the optomechanical backaction, confirming the potential of rare-earth-based systems as promising hybrid mechanical systems.

Strain-mediated ion–ion interaction in rare-earth-doped solids

“…If the particle is embedded in a solid matrix, this piezo-orbital backaction effect will additionally give rise to a stress field around the excited particle, making it detectable via a change of shape of the solid itself. This was recently evidenced in a bulk REIC in which only a finite volume of the crystal was illuminated, leading to a distortion of the nearby crystal surface [30].…”

“…Let us now focus on the mechanical consequences of a change of state in a matrix-embedded rare-earth ion. Under optical excitation, due to piezo-orbital backaction [30], the rearrangement of the electronic orbitals is expected to alter the ion's apparent size.…”

Strain-mediated ion-ion interaction in rare-earth-doped solids

“…If the particle is embedded in a solid matrix, this piezo-orbital backaction effect will additionally give rise to a stress field around the excited particle, making it detectable via a change of shape of the solid itself. This was recently evidenced in a bulk rare-earth ion-doped crystal in which only a finite volume of the crystal was illuminated, leading to a distortion of the nearby crystal surface [30].…”

“…Relating the strain energy with the atomic energy Due to piezo-orbital backaction [30], the size of a rare-earth ion is expected to change under optical excitation. Assuming this change of shape is merely a change of radius on a spherical ion, we can apply the calculation presented in appendix Appendix A.…”