Excitation of phonons by electromagnetic pulses in view of propagation effects in the medium

This study examines the excitation of transverse optical phonons in a semiconductor sample under the action of electromagnetic pulses of arbitrary duration, in view of their passage through the interface and absorption in matter. A universal formula for the total absorption coefficient through the components of the complex refractive index of the medium is derived. The dependences of phonon excitation efficiency on the sample thickness and excitation pulse parameters are examined using the example of a GaAs sample and pulses with Gaussian envelope. The specific features of the considered process are established for the carrier frequencies of the pulse inside and outside the photonic forbidden zone.