Design of an experimental setup for the measurement of light-driven atomic mass density waves in a silicon crystal

摘要

The recently introduced mass-polariton (MP) theory of light describes light in a medium as a coupled state of the eld and matter [Phys. Rev. A 95, 063850 (2017)]. In the MP theory, the optical force density drives forward anatomic mass density wave (MDW) that accompanies electromagnetic waves in a medium. The MDW is necessaryfor the fulfilment of the conservation laws and the Lorentz covariance of light. In silicon at wavelength λ_0 = 1550nm, the atomic MDW carries 92% of the total momentum and angular momentum of light. The MDW of a lightpulse having field energy E propagating in a dielectric also transfers a net mass equal to δM = (n_pn_g-1)E=c~2,where n_p and n_g are the phase and group refractive indices. In this work, we present a schematic experimentalsetup for the measurement of the MDW in a silicon crystal. This setup overcomes many challenges that havebeen present in previously introduced setups and that have made the experimental observation of the MDW effectdiffcult due to its smallness in comparison with other effects, such as the momentum transfer by absorption andreections. The present setup also overcomes challenges with elastic relaxation e ects while extending possiblemeasurement time scales beyond the time scale of sound waves in the setup geometry. For the proposed setup,we also compare the predictions of the MP theory of light to the predictions of the conventional Minkowskitheory, where the total momentum of light is carried by the electromagnetic field. We also aim at optimizingexperimental studies of the MDW e ect using the proposed setup.