Patent ID: 7729588
Filing Date: 2010-06-01
Classification: C03B,G02B,H01S

Abstract:
1. An optical amplifier comprising: an optical fiber including: a first core portion doped with rare earth ions; a second core portion having a lower refractive index than that of the first core portion and provided along an outer circumference of the first core portion, the second core portion being doped with rare earth ions of a higher concentration than that of the first core portion; and a clad portion having a lower refractive index than that of the second core portion and provided along an outer circumference of the second core portion; a forward pump unit that inputs first forward pump light in 980-nm band and second forward pump light in 1480-nm band to an input end of the optical fiber; and a backward pump unit that inputs backward pump light in 1480-nm band to an output end of the optical fiber, wherein population inversion ratios in the first and second core portions of the optical fiber are controlled by controlling an intensity ratio between the first forward pump light and the second forward pump light.