Generation of octave-spanning spectra inside reverse-photon-exchanged periodically poled lithium niobate waveguides.

We demonstrate simultaneous octave-level spectral broadening and carrier-envelope-offset sensing of mode-locked Er- and Yb-doped femtosecond fiber lasers using constant-period and chirped reverse-proton-exchanged periodically poled lithium niobate waveguides. Chirped quasi-phase-matching gratings greatly improve spectral broadening of Yb-fiber lasers.