Inter-Mode Forward Brillouin Scattering in Nanofibers

Abstract

We investigate the inter-mode forward stimulated Brillouin scattering (FSBS) in nanofibers in this article. An extraordinary high Brillouin peak value is predicted for the interaction between the HE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> and the high-order optical mode (TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> ). The corresponding excited acoustic mode (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> ) has the characteristics of the relatively uniform large normalized displacements and the phase velocity less than the shear acoustic velocity of silica, which completely differs from the transverse acoustic mode in the intra-mode FSBS process of the HE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> . The Brillouin peak value by the contribution of R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> can reach 260.5 W <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> at a frequency of 0.1905 GHz, which is at least an order of magnitude higher than the maximum peak value in the intra-mode forward Brillouin gain spectrum (BGS). Moreover, for a nanofiber radius of 0.57 to 1 μm, the contribution of R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> is always the most prominent to the BGS. This work provides further insight into phonon-photon coupling in nanofibers.