1-μm-wavelength ytterbium-doped fiber laser based on the third harmonic reflection in secondary-type-In Bragg gratings.

In this Letter, a 1-μm-wavelength fiber laser is proposed through the use of the ytterbium-doped active fiber and the third harmonic Bragg reflectors. Benefiting from the ratio below 0.5 between the core diameter of the fiber and the Talbot length of the UV fringes, enabling the formation of the secondary-type-In grating, the reflector with reflectivity higher than 95% at two-thirds of the designing Bragg wavelength can be fabricated within 2 min. Inherited by the lower temperature and strain sensitivity of the third harmonic grating, the laser has good wavelength stability and could be used as a reliable laser resource. In addition, this Letter can also be expected to provide great flexibility in fiber laser wavelength design.