SBS Suppressed Fiber With Hole-Assisted Structure

This paper describes a fiber design that incorporates a hole-assisted structure for suppressing stimulated Brillouin scattering (SBS). The proposed hole-assisted fibers (HAFs) have a simple structure with a low relative index difference and/or a small core radius. We suppress the SBS by extending the optical field into the cladding region, which reduces the overlap between a lightwave and an acoustic wave both in the fundamental mode. The bending loss remains low because of the optical field confinement provided by the air holes. We discuss the impact of the core profile on the SBS gain spectrum and show numerically a 13.5 dB improvement in the SBS threshold with both a low SBS gain and a large effective area. Moreover, we show that we can realize SBS suppressed HAF with a low bending loss and almost the same mode field diameter as SSMF by designing the air hole structure. Finally, we experimentally confirm the SBS suppression effect by using the fabricated HAF.