A Ti: sapphire oscillator emitting an octavespanning spectrum that ra nges from 460nm to 1000nm is demonstrated. To our knowledge, it is the first tim e that a supercontinuum extending beyond 500nm in the blue end is generated from a femtosecond oscillator. The selfQswitched and selfmodelocked Ti: sapphi re oscillator uses chirped mirrors and a prism pair for dispersion compensation. Th ese results will make the measurement of carrierenvelope offset frequency simp ler and improve the stability of optical frequency metrology at the same time.