An ASE light source offers high outputs even in a wavelength band of 1,490 to
1,525 nm. The ASE light source outputs spontaneous emission light generated from
Tm-doped optical fibers. Then, the ASE light source outputs amplified light obtained
by using Er-doped optical fibers to amplify the output from the Tm-doped optical
fibers and spontaneous emission light generated from the Er-doped optical fibers
so that the amplified light and the spontaneous emission light are superimposed
on each other.
