A polarization-insensitive multiple-quantum-well optical amplifier for 1.3 μm wavelength employing both four compressively-strained wells (1.0% strain, 6 nm well width) and three tensile-strained wells (-0.95% strain, 11 nm well width) in active region was grown by low pressure metalorganic vapor phase epitaxy (LP-MOVPE). The amplifier was fabricated forming ridge waveguide structure with 7° tilted cavity. The two facets were coated with two layers Ti3O5/Al2O3 anti-reflection (AR) thin films, residual facet reflectivity was found to be less than 3×10-4. The 3-dB bandwidth of the amplified spontaneous emission (ASE) spectra was above 50 nm and the amplitude of the optical power ripple was bellow 0.4 dB. The amplifier exhibited an excellent polarization insensitivity (less than 0.6 dB) over the entire range of wavelength (1.28～1.34 μm). A small signal gain of 30 dB and a saturated output power of more than 10 dBm at bias current of 200 mA and 1305 nm wavelength were obtained. The noise figure of the amplifier was 7.5 dB.