Whispering-gallery　mode　(WGM)　microcavities　are　known　for　their　high-quality　factor,　small　mode　volume,　and　high　power　density.　These　properties　have　made　them　a　subject　of　significant　interest　in　both　fundamental　researches　and　practical　applications,　particularly　in　the　field　of　stimulated　Raman　scattering.　In　this　study,　we　combine　WGM　with　the　photothermal　effect　of　a　microsphere　to　achieve　broadband　all-optical　tuning　of　cascade　Raman　laser.　By　employing　a　heating　laser　to　preciously　tuning　the　photothermal-induced　change　of　both　the　size　and　refractive　index　of　a　silica　microsphere,　four-order　cascaded　Raman　lasers　with　a　wavelength　from　981.0　to　1192.22　nm　generated　with　an　average　wavelength　tunable　region　of　0.449　nm.　The　resulting　broadband　tunability　of　emission　wavelength　within　both　the　NIR-II　biomedical　window　and　Yb-doped　fiber　amplifier　ranges　for　O-band　optical-fiber　communication,　highlighting　the　potential　applications　in　optical　sensors,　optical　communication,　bioimaging,　and　biomedical　science.　©　2025　Author(s).