Efficient Er3+‐doped optical fiber amplifier pumped by a 1.48 μm InGaAsP laser diode

Optical gain characteristics of an Er3+ ‐doped silica fiber have been studied by end pumping with a 1.48 μm InGaAsP high‐power laser diode. A gain as high as 12.5 dB was obtained for an absorbed pump power of 16 mW with a 3‐m‐long fiber. By constructing an Er3+ fiber ring cavity with a 3 dB single‐mode fiber coupler, we have obtained continuous wave laser oscillation at a wavelength of 1.553 μm.