| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an inexpensive signal light disconnection detecting method capable of suppressing the influence of noise light while securing immediacy and an optical amplifier that uses the signal light disconnection detecting method. <P>SOLUTION: This optical amplifier 1 branches a portion of input light outputted from a transmission line fiber 2 as monitor light Lm to convert it into an electrical signal, extracts a frequency component corresponding to a period where a head area of a framed signal light Ls appears on the basis of the electrical signal, detects signal light input disconnection when a voltage level at which the frequency component is converted into a direct current is lower than reference voltage and performs shutdown control of an excitation light source 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
