The compressivelystrained quantum wells, tensilestrained quantum wells and the combination of tensilestrained and compressivelystrained quantum wells were grown by metal organic vapor phase epitaxy, the materials properties were meas ured by photoluminescence spectra and x-ray doublecrystal diffraction. A polarizationinsensitive multiplequantumwell optical amplifier for 1310nm wavelength employing both compressively strained wells and tensilestrained wells in active region is reported. The amplifier was fabricated to ridge waveguide structure with 7° tilted cavity, the two facets were coated with antireflection thin films. The amplifier exhibited an excellent polarization insensitivity (less than 0.6dB) over the entire range of wavelength (1.28-1.34μm) and a fiber to fiber gain of 21.5B at bias current of 200mA.