LIGHT STIMULATED EMISSION DEVICE

摘要

PROBLEM TO BE SOLVED: To realize a light stimulated emission device which is capable of operating in a single mode to serve as a fiber laser amplifier that is compatible with an end pumping communication optical fiber system by a method in which stimulated emission is obtained through a three-level system where impurities of low concentration are dispersed in the optical fiber system along its lengthwise direction. SOLUTION: An amplifier is formed of a doped fiber 1 provided with an open end 4 and a port coupler 29. The amplifier is inserted into a transmission fiber 35. Signals of emission wavelength are transmitted along the main fiber 35 which functions as gain medium. Pumping radiation from a source 31 is connected to a connecting fiber 33, where the pumping radiation is connected to the main fiber 1. An amplifier can be improved in efficiency through that a coupler is designed so as to connect pumping radiation but not to connect radiation of emission wavelength to the fiber 1. Therefore, an amplifier which is capable of operating in a single mode and compatible with a single mode fiber system can be obtained.