Mode field adaptation between single-mode fiber and large mode area fiber by thermally expanded core technique

The main source of light transmission loss between single-mode fiber (SMF) and large mode area (LMA) fiber is from the mode field mismatch. Thermally expanded core (TEC) technique was introduced to realize mode field adaptation between them. The SMF was heated by a H2–O2 flame to increase the mode field diameter (MFD) which can result in a mode field match with LMA. Both numerical calculation and experiment results show it is workable to realize mode field adaptation and get a low transmission loss by this method. For HI1060 (d=5 μm, NA=0.14) and LMA-GDF-15/130(d=15 μm, NA=0.08), a low-loss with 0.4 dB was obtained for SMF–LMA–SMF from 6.4 dB with TEC processing experimentally.

► We realize mode field adaptation between SMFs and LMA by TEC technique.
► A H2–O2 flame was used to increase the MFD of SMFs.
► A low loss was got between SMFs and LMA.
► This method is convenient and effective.