PURPOSE: To provide an optical amplifier employing an Er doped optical fiber in which the polarization dependency is substantially eliminated, the loss is suppressed, and the output can be monitored.
CONSTITUTION: The optical amplifier comprises an inlet side fiber/lens assembly 11 secured to the side wall 4A at the outlet of an Er doped optical fiber 1, and a pump side fiber/lens assembly 31 secured to the opposing side wall 4C. The optical amplifier is set in the housing 4 while inclining by 22.5° with respect to the optical axis of the inlet side fiber/lens assembly 11. The optical amplifier further comprises a wavelength split optical film 5 which reflects the light from the Er doped optical fiber 1 and transmits the pumping light from a pump light source 3, a coupler film 7 disposed in the housing 4 in order to reflect the light on the film 5 in parallel with the optical axis of the inlet side fiber/lens assembly 11, and an outlet side fiber/lens assembly 21 secured to the opposing side wall 4C at the inlet of an output optical fiber 2 in order to receive the light reflected on the coupler film 7.
NAGANUMA NORIHISA
KUBO TERUHIRO
