Ge-based　chalcogenide　glass　fibers　exhibit　a　high　damage　threshold　and　exceptional　water　stability,　making　them　an　ideal　material　for　transmitting　Er:　YAG　laser　beams.　However,　the　problem　of　particle　scattering　in　the　current　glass　poses　formidable　challenge　to　the　transmission　of　high-power　Er:　YAG　lasers.　In　this　study,　we　introduce　what　we　believe　to　be　a　novel　approach　to　mitigate　internal　scattering　by　employing　a　micron-scale　filter　in　combination　with　a　multi-stage　dynamic　distillation　process,　effectively　extending　the　purity　limits　of　Ge-CHG　fibers.　The　loss　of　Ge-As-S　glass　has　achieved　a　record　of　0.1　dB/m　by　reducing　the　internal　particle　scattering.　In　addition,　the　Ge-As-S　optical　fiber　prepared　by　the　isolation　extrusion　method　also　exhibits　excellent　performance　in　the　transmission　of　Er:　YAG　laser.　The　Ge-As-S　fiber　rod　with　a　core　diameter　of　approximately　750　µm　can　sustain　a　laser　power　of　13.43　W　at　wavelength　of　2.94　µm,　i.e.,　energy　density　of　684　J/cm2　under　atmosphere　surrounding.　To　enhance　flexibility,　the　fiber　rod　was　tapered　to　gradually　reduce　its　diameter,　achieving　a　core　diameter　of　300　µm　at　the　narrow　end.　The　flexible　Ge-As-S　fiber　achieved　a　maximum　power　output　of　4.1　W　with　an　energy　density　of　580　J/cm2.　To　our　knowledge,　this　is　the　first　instance　of　a　chalcogenide　fiber　handling　Er:　YAG　laser　power　exceeding　5　W　flexibly.　Finally,　we　demonstrated　the　capability　of　the　flexible　optical　fiber　to　transmit　Er:　YAG　laser　energy　for　biological　tissue　ablation,　achieving　a　cutting　depth　of　3　mm.　These　results　highlight　the　potential　of　Ge-As-S　fibers　as　a　promising　platform　for　high-power　mid-infrared　laser　transmission,　with　significant　applications　in　minimally　invasive　surgery　procedures.　©　2025　Optica　Publishing　Group　under　the　terms　of　the　Optica　Open　Access　Publishing　Agreement.