All-polarization-maintaining Nd-doped ultrafast fiber laser oscillator at 929 nm mode-locked via a 3x3 nonlinear amplifying loop mirror

Successful generation of ultrashort pulses in the spectral region of 920 nm using Nd-doped fibers requires effectively suppressing the dominant 1064 nm four-level transition. Utilizing a hybrid design incorporating a W-shaped double-clad Nd-doped fiber and a single-clad Nd-doped fiber together with filtering out parasitic 1.06 mu m beam, we developed an oscillator capable of delivering ultrashort pulses at the central wavelength of 929 nm. Here, we transferred the crucial components of the technology from the well-developed Yb-doped systems to build an all-polarization-maintaining Nd-doped fiber laser oscillator. The ultrashort pulsed operation is obtained through the passive mode-locking via a nonlinear amplifying loop mirror based on a 3x3 fiber coupler. The self-starting system has a figure-of-8 all-normal-dispersion cavity design and operates in a dissipative soliton regime. The oscillator, generating pulses with energy exceeding 1 nJ, delivers chirped 14.3 ps pulses, which can be compressed to 313 fs.