When EFA developed by PreciLasers amplify the seed laser power, the increase of the frequency and intensity noise is kept in the extreme low range. The linewidth is less than 10 Hz, and the intensity noise (RIN) is less than -140 dBc/ HZ@ 100 kHz. Compared to the scheme of amplified directly 780 nm diode laser power, the scheme of utilizing the Er-doped fiber amplifier (EFA) as 1560 nm laser power amplifier adopted by Precilasers have higher power. The maximum laser power outputted with stable and long lifetime by EFA can be up to 15 W. Due to all fiber structure, the EFA have the excellent environmental stability.