Combined Method for SBS Suppression in High Numerical Aperture Single-Mode Optical Fibers

• Published in: IEEE photonics technology letters 2022-10, Vol.34 (20), p.1069-1072
• Main Authors: Khudyakov, Maxim M., Tsvetkov, Sergey V., Kosolapov, Alexey F., Bubnov, Mikhail M., Lobanov, Alexey S., Lipatov, Denis S., Guryanov, Alexey N., Likhachev, Mikhail E.
• Format: Article
• Language: English
• Subjects: acoustic index profile; Acoustics; Aluminum oxide; Brillouin gain spectrum; Coiling; Compressive properties; Doped fibers; Germanium oxides; High-numerical-aperture optical fiber; Numerical aperture; offset-core optical fiber; Optical fiber amplifiers; Optical fiber communication; Optical fiber polarization; Optical fibers; Refractive index; Refractivity; SBS gain suppression; Scattering; stimulated Brillouin scattering; strained optical fiber; Stress
• ISSN: 1041-1135; 1941-0174
• DOI: 10.1109/LPT.2022.3200152

We propose and test a combined method of suppression of stimulated Brillouin scattering (SBS) in high numerical aperture (NA) optical fibers that makes it possible to use both the application of tensile-compressive stresses and the control of the transverse acoustic refractive index profile. In the experiment on the acoustically tailored Al 2 O 3 -GeO 2 -doped fiber (optically step-index, NA \sim ~0.2 ) with a quasi-four-peak SBS gain spectrum \sim 0.8 GHz wide, we used the offset-core technique to create a tensile-compression stress over the whole fiber length, controlled by small-diameter coiling. The stress causes each of the spectral peaks to broaden without overlap. Thus, at the optimal coiling diameter, an 11.3dB net SBS gain suppression has been obtained, where \sim 5 dB is due to the tension. Ways to enhance SBS suppression in such fibers up to 18dB and more using the proposed technique are also discussed.