Forward stimulated Brillouin scattering in optical nanofibers

We comprehensively investigate the process of forward stimulated Brillouin scattering in nanofibers, considering the electrostrictive body force, electrostrictive pressure, and radiation pressure. The forward Brillouin gain spectrum in a radio frequency range from 1 to 14 GHz is analyzed for nanofiber radii varying from 150 to 1500 nm. Only transverse acoustic modes contribute to the forward Brillouin gain because of the transverse nature of optical forces in forward scattering. We reveal that, during the process of forward stimulated Brillouin scattering, the Brillouin effects caused by the low-order surface transverse acoustic modes play a dominant role in the gain spectrum. The photoacoustic mechanism of forward stimulated Brillouin scattering in nanofibers may open new avenues in many applications, such as optical sensing.