Tunable mode-locked fiber laser using multifunctional long-period grating

A laser has been demonstrated to achieve tunable mode-locked operation using a multifunctional long-period fiber grating (LPFG).By introducing an LPFG with a relatively high polarization-dependent loss of up to 21 dB into the laser cavity, a stable fundamental frequency mode-locked operation was achieved at 1546.26 nm.We also have achieved a wavelength-tunable 40th-harmonic mode-locked laser with a tuning range of nearly 10 nm through simple thermal tuning, based on the tunable attenuation characteristics of the grating.The results indicate that the LPFG can simultaneously act as a polarizationselective and wavelength-selective element in mode-locked lasers.