Environmentally-stable all-normal-dispersion picosecond Yb-doped fiber laser with an achromatic quarter-wave-plate

We present an environmentally-stable picosecond Yb-doped fiber laser by employing an achromatic quarter-wave-plate (AQWP) as a pulse stabilizer in the all-normal-dispersion and polarization-maintaining linear laser cavity. It is shown that the AQWP plays a critical role to control both the polarization state and spectral filtering of the proposed mode-locked laser. The demonstrated laser generates 2-ps-long pulses with pulse energies of 1 nJ at a repetition rate of 117 MHz and parabolic spectral width of 26 nm. The fundamental RF carrier frequency exhibits Allan deviation of 3.8 × 10⁻⁸ at 1-s averaging time and phase noise of −95 dBc/Hz at 10-Hz offset frequency.