We present a novel design of a compact, stable, and easy-adjustable semiconductor optical amplifier (SOA) system. This SOA system is capable of providing up to 560-mW laser power at the wavelength of 852 nm. For the continuous-wave (CW) seeding laser, the amplification gain can reach 18 dB. We add amplitude modulation onto the CW laser and measure the modulation amplification between seeding and output laser. The amplification gain remains constant within the frequency range from 10 Hz to 1 MHz. The whole system could work in ultra-stable condition: for CW seeding laser, the fluctuation of output power is less than 0.33% in several hours.