Connet's sub-picosecond pulsed Erbium-doped fiber laser adopts an all-fiber design. It is a fully polarization maintaining fiber laser based on SESAM passive mode-locking. It achieves a stable linearly polarized sub-picosecond laser output through an optimized design of the optical path. The product has high reliability and maintenance free. The laser can be used for scientific research or as a seed laser for high-power industrial ultrafast pulse lasers.