The erbium doped fiber amplifier (EDFA) gain flattening filters were fabricated by writing long period gratings in hydrogen-loaded standard single-mode fibers using amplitude masks and a properly designed program controlled scanning exposure system. The gain variation of ±3 dB in an EDFA is reduced to ±0.3 dB over a bandwidth of 30 nm and the total extra insertion loss of the device is less then 0.3 dB.