TiO_2/SiO_2 multiple layers anti-refledtion (AR) coatings for the facets of 1.55 μm polarization insensitive semiconductor optical amplifiers were designed and fabricated. Less than 5×10 -4 reflectivities were obtained for both two layers and four layers AR coatings. An In-Situ monitoring for reflectivity was designed and employed during the coating process. The amplifier was fabricated forming ridge waveguide structure with 7° tilted cavity, which showed a less than 0.4 dB ASE ripple, a more than 52 nm bandwidth, excellent polarization insensitivity (less than 0.5 dB) over the entire range of wavelength (1.52~1.58 μm) and a gain of 27 dB at bias current of 200 mA and 1550 nm wavelength.