Phonons induced by laser pulses for Brillouin scattering measurements

Abstract

To overcome the problem of low intensity of Brillouin scattered light from thermal phonons, we stimulated the Brillouin scattering by inducing coherent phonons in a glass sample. To develop a completely noncontact measurement method, we induced phonons at 500–800 MHz by a picosecond pulse laser technique and studied how these affect the scattered light. Results show an increase in the intensity of scattered light if the stimulation with the pulse laser is performed. At a distance of 0.75 mm between the pulse laser and the probe laser, we were able to observe an increase of 34 times in the intensity of scattered light. By using a much smaller pulse length of the laser, we can expect stimulation in the GHz range in the future.