  Selection of operating wavelength of the Yb-doped fiber-ring lasers using
longperiod fiber gratings (LPFGs) is suggested. In the proposed method,
customized LPFG that sustains high powers serves as a broad-band rejection
filter. It modifies the net gain profile of the laser, enabling the peak gain
to occur at a designed wavelength. Spectral range of oscillation between
1050-1110 nm was experimentally demonstrated. This range can be extended to
both shorter and longer wavelengths with proper design of the LPFG and length
of the Yb-doped fiber. The gratings were inscribed by CO2 laser and the grating
period down to 175 ?m was achieved being, to our best knowledge, the shortest
reported LPFG period using this technique.
