Patent ID: 6031660
Filing Date: 2000-02-29
Classification: H01S,H04B

Abstract:
An analog double automatic power controlling device in an optical fiber amplifier having two optical isolators respectively positioned at input and output ends, for preventing reverse surge of an optical transmission signal, a wavelength division multiplexer for multiplexing an externally input optical transmission signal and an optical excitation signal, a pump laser diode for generating the excitation signal, and an output tap at the output end, for dividing an amplified optical signal at a predetermined ratio, comprising:a pump laser diode controlling portion for driving the pump laser diode to output the optical excitation signal, and automatically controlling the intensity of the excitation signal on the basis of the level of a fed-back signal;a first feed-back controlling portion for detecting an optical signal divided at the predetermined ratio via the output tap, converting the optical signal to a first electrical signal;a second feed-back controlling portion for detecting the optical excitation signal output from the pump laser diode controlling portion, converting the optical excitation signal to a second electrical signal;a switch for switching to connect one of the first and second electrical signals to the pump laser diode controlling portion; anda switch controlling portion for sensing a current flowing through the pump laser diode, comparing a sensed current level with a predetermined reference current level, and generating a switch controlling signal for output to the switch on the basis of the comparison result, for causing the switch to select one of the first and second electrical signals as the fed-back signal for input to the pump laser diode controlling portion.