Wavelength-multiplexed light amplifying apparatus,optical amplifier and optical add-and-drop apparatus using wavelength-multiplexed light amplifying basic unit

Abstract

The present invention relates to a wavelength-multiplexed light amplifying apparatus to be used in a state of being connected to a branching portion of a multiplexing/branching unit or to be used for a m×n matrix optical switch of an optical cross-connect. The wavelength-multiplexed light amplifying apparatus is composed of a plurality of wavelength-multiplexed light amplifying units and an optical feedback loop system. A signal input port of an optical branching section in one wavelength-multiplexed light amplifying unit is connected to an output side of an optical amplifying section in the preceding wavelength-multiplexed light amplifying unit. This configuration disperses the power loss of an optical signal to perform amplification with high efficiency and further enables the expansion of the branching port in the in-service. Additionally, it can eliminate the need for the installation of an optical isolator or reduce the required value of isolation to stabilize the system, or can accomplish the control to maintain the gains of all ports constant.

What is claimed is:  
     
         1 . An optical amplifier, comprising: 
 an optical filter provided on an input side of a monitoring unit, said monitoring unit monitoring an optical signal, to allow a passing of a signal light component as well as remove an excitation light component from the optical signal.    
     
     
         2 . An optical amplifier, comprising: 
 an optical filter provided between an optical coupler, said optical coupler performing an optical coupling, and a detecting unit, said detecting unit is for detecting an input light, to allow a passing of a signal light component as well as remove an excitation light component from the input light.    
     
     
         3 . A wavelength-multiplexed light amplifying apparatus, comprising: 
 an input monitoring unit, said input monitoring unit including an optical filter which allows a passing of a signal light component from an input light as well as removes an excitation light component from the input light.