| 摘要 |
PROBLEM TO BE SOLVED: To provide a direct optical amplifier which monitors the deterioration of an S/N ratio and signals when an S/N ratio deteriorates by detecting an S/N ratio in each signal light wavelength of input light (or output light). SOLUTION: This direct optical amplifier is provided with a light branch/ combine means 1 to branch wavelength multiple signal light, a direct optical amplifier means 2 that directly amplifies branched signal light and outputs it, a signal light/noise light dividing means 3 which separates a wavelength multiple signal light components of another branched signal light from a noise light component, a 1st light receiving means 11 which receives a signal light component and detects a signal light level, a 2nd light receiving means 21 which receives a noise light component and detects a noise light level, an S/N ratio operating means 51 which calculates an S/N ratio and outputs it based on a signal light level of each wavelength and on a noise light level corresponding to each signal light, and an S/N ratio deterioration detecting means 7 which compares the S/N ratio with a reference value and generates an alarm when an S/N ratio deteriorates. |
