Highly efficient configuration of a Pr/sup 3+/-doped fluoride fiber amplifier module with an optical circulator

A highly efficient Pr/sup 3+/-doped fluoride fiber amplifier configuration with an optical circulator, in which the input signal light is amplified both forward and backward through a Pr/sup 3+/-doped fluoride fiber, is investigated with a view to decreasing the drive current and improving the reliability of pump laser diodes (LD's). With this double-path configuration, a 25-dB signal gain is achieved at an LD drive current of 110 mA. This LD drive current is about half that needed for a conventional single-path configuration. It is also found that this double-path configuration provides a double-gain coefficient, a slightly low saturation power, and a slightly narrow spectral gain width.<
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