Passive mode locking by carbon nanotubes in a femtosecond laser written waveguide laser

The authors report on the first demonstration of mode locking in an active waveguide laser manufactured by femtosecond laser writing. The active waveguide is fabricated in an Er–Yb-doped phosphate glass, and the mode locker is a fiber-pigtailed saturable absorber device based on single-wall carbon nanotubes specially designed to efficiently operate at 1.5μm. Transform-limited 1.6ps pulses were observed in a ring laser cavity configuration.