1.06 &mgr;m band optical amplifier apparatus utilizing induced emission in optical fiber by excited rare-earth element

Abstract

In an optical amplifier apparatus for amplifying an incident signal light having wavelengths of 1.06 &mgr;m band, a first optical isolator makes an incident signal light pass therethrough in one direction from an input end to an output end. An optical fiber includes a core mainly composed of silica glass and doped with a predetermined rare-earth element and the other elements, and a cladding of silica glass, and transfers in a single mode the signal light output from the first optical isolator. An optical multiplexer multiplexes an excitation light having an excitation wavelength of 0.8 &mgr;m band with the signal light transferred by the optical fiber, by outputting the excitation light to the optical fiber, and further transfers and outputs the signal light having wavelengths of 1.06 &mgr;m band amplified by induced emission in the optical fiber due to the rare-earth element excited by the excitation light. Further, a second optical isolator makes the signal light outputted from the optical multiplexer pass therethrough in one direction from an input end thereof to an output end thereof, and outputs the signal light as an amplified signal light.