A 100W polarization maintaining cladding light stripper with ultralow polarization extinction ratio degradation

We demonstrate a polarization maintaining (PM) cladding light striper (CLS) with ultra-low backscattering, which can handle a residual pump power of 100 W. Using our previously proposed a periodically grooved CLS structure with multiple unetched sections of a suitable length, a CLS based on a 20/400 um PM large mode area (LMA), double clad fiber (DCF) was designed and fabricated. A hydrogen fluoride (HF)-free chemical etching technique was used for the fabrication considering fabrication and environmental safety. The pump stripping efficiency was ~98.7% and the backscattering level was ~0.13%. The degradation of the polarization extinction ratio at the CLS output was ~0.2 dB. The degradation of the polarization extinction ratio at the CLS output was only ~0.2 dB.