Abstract

Er³⁺-doped fiber amplifiers are very useful for optical communication systems because of their characteristics of high gain, low noise, polarization insensitivity, and high saturation output.^1,2 There are many pump-bands for Er³⁺-doped fibers, and in particular the 0.8^3,4, 0.98^5,6, and 1.48⁷ μm bands have the potential for laser diode pumping. From among these pump bands, the 0.8 μm band is attractive because inexpensive high output GaAlAs laser diodes can be used. However, it has been thought difficult to obtain a high gain with this pumping line since because of the existence of excited state absorption (ESA)⁸. Recently, high gain amplification using a 0.8 μm band Ti:Sapphire laser was reported⁹. The optimum pumping wavelength was around 820 nm.

© 1990 Optical Society of America