Stimulated Brillouin scattering (SBS) processes in optical fibers are driven by two optical field components. In most cases, SBS requires that the two fields are co-polarized. However, the process may also be stimulated by two orthogonally polarized optical waves, even though their combined intensity does not include a beating pattern. The process has been demonstrated before in specialty, nano-structured optical fibers. In this presentation, I describe forward SBS processes in standard single-mode and polarization-maintaining (PM) fibers that are driven by orthogonal optical pump waves. In PM fibers, in particular, the axial wavenumbers of the stimulated acoustic waves are 1,000 times larger than those of standard forward SBS processes. This property leads to inter-polarization coupling of optical probe waves that is non-reciprocal. The results may serve for new concepts of distributed optical fiber sensors, microwave-photonic signal processing, and opto-mechanical isolators.
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