400mW 1060nm ytterbium doped fiber DFB laser

We report for the first time, more than 400mW of output power at 1056.1nm from a distributed feedback (DFB) fiber laser. The DFB fiber laser comprises a simple pi-phase-shifted Bragg grating written into a photosensitive ytterbium-doped fiber. The laser operates with a single longitudinal mode at a wavelength defined by the phase shift and the grating period. Without any internal polarisation selection mechanism, the cavity supports orthogonal polarisation modes, which operate simultaneously. The DFB fiber laser was pumped by a 976nm amplified spontaneous emission (ASE) source based on a ytterbium doped jacketed air clad (JAC) fiber pumped by a 915nm multimode laser diode source. An output of 400mW at 1056.1nm was obtained from the output port while 70mW was obtained from the other port, when pumped with 1.5W of 976nm radiation. The total output from the DFB fiber laser was approximately linear with increasing pump power and the overall performance was limited by the available pump power. The spectral characteristics and signal to noise ratio remained similar over the pump power range. The output of the DFB was in single-mode fiber (ie. M2~1)