Patent ID: 7586673

Claim:
A method of controlling optical amplification comprising the steps of: preparing an Al-codoped optical gain waveguide whose optical waveguide region is doped with Er element, said optical waveguide region containing F element or B element together with Er element; and supplying said optical waveguide region with pumping light having a wavelength of 976 nm or less, or a wavelength of 981 nm or more, which is set so as to have an optimized population inversion of Er in said optical waveguide region such that two peaks in a C-band gain spectrum come to an equivalent level, whereby a gain variation of said Al-codoped optical gain waveguide in the C-band is minimized, wherein, when the pumping light having the wavelength of 976 nm or less, or the wavelength of 981 nm or more is supplied to said optical waveguide region, a relative gain variation of said Al-codoped optical gain waveguide, defined by a peak gain value and a minimum gain value in a wavelength band of 1,530 nm to 1,560 nm, becomes smaller than 11.5%.