Gain controlling of erbium-doped fiber amplifier by samarium doped inner-cladding in the 1.5 μm region

Characteristics of a new type of erbium-doped fiber for optical amplifiers were reported where erbium was doped in the center of the core and samarium doped in a ring of the cladding. Using samarium absorption of photons around 1.5 μm in the erbium ion emission range, we demonstrated a new way of controlling the gain spectrum of erbium-doped fiber amplifier without using external filters. Amplifier small signal gain under saturation was about 11 dB and within 2.3 dB variation in the range of 1520-1560nm. Total output power from the amplifier was 9 dBm with 100mW of pump power at 980nm. The effects of samarium-doped inner cladding on amplified spontaneous emission spectra in the long wavelength band were also reported.