We　demonstrated　an　abnormal　double-peak　(annular　shaped)　energy　deposition　through　dual-wavelength　synthesis　of　the　fundamental　frequency　(omega)　and　the　second-harmonic　frequency　(2　omega)　of　a　femtosecond　(fs)　Ti:　sapphire　laser.　The　annular　shaped　distribution　of　the　dual-wavelength　fs　laser　was　confirmed　through　real　beam　shape　detection.　This　uniquely　simple　and　flexible　technique　enables　the　formation　of　functional　plasmonic　nanostructures.　We　applied　this　double-peak　fs-laser-induced　dewetting　effect　to　the　controlled　fabrication　and　precise　deposition　of　Au　nanostructures,　by　using　a　simple,　lithography-free,　and　single-step　process.　In　this　process,　the　double-peak　energy-shaped　fs　laser　pulse　induces　surface　patterning　of　a　thin　film　followed　by　nanoscale　hydrodynamic　instability,　which　is　highly　controllable　under　specific　irradiation　conditions.　Nanostructure　morphology　(shape,　size,　and　distribution)　modulation　can　be　achieved　by　adjusting　the　laser　irradiation　parameters,　and　the　subsequent　ion-beam　polishing　enables　further　dimensional　reduction　and　removal　of　the　surrounding　film.　The　unique　optical　properties　of　the　resulting　nanostructure　are　highly　sensitive　to　the　shape　and　size　of　the　nanostructure.　In　contrast　to　a　nanoparticle,　the　resonance-scattering　spectrum　of　an　Au　nanobump　exhibites　two　resonance　peaks.　These　suggest　that　the　dual-wavelength　fs　laser-based　dewetting　of　thin　films　can　be　an　effective　means　for　the　scalable　manufacturing　of　patterned-functional　nanostructures.