Patent ID: 6118576
Filing Date: 2000-09-12
Classification: H01S,H04B

Abstract:
An optical amplifier that controls amplification action in accordance with an input light level, comprising:an input monitor for monitoring the input light level;a first optical fiber amplifier, located on the input side of said input monitor, amplifying the input light in accordance with excitation light supplied to the first optical fiber amplifier, the first optical fiber amplifier amplifying the input light with a gain that is larger than the loss due to said input monitor; anda second optical fiber amplifier, located on the output side of said input monitor, amplifying the light that has passed through said input monitor,wherein, when excitation light is not being supplied to the first optical fiber amplifier, a loss in the first optical fiber amplifier is less than the difference between a minimum light level prescribed in a system in which the optical amplifier is installed and a minimum light level that said input monitor can detect.