Variable optical dispersion compensating module

Abstract

The present invention provides a variable optical dispersion compensating module comprised of (a) an optical dispersion compensating unit having an input optical switch, an optical dispersion compensating fiber, connected to the optical switch, having a predetermined optical dispersion amount, a bypass path for bypassing the optical dispersion compensating fiber, and an output optical switch connected to the optical dispersion compensating fiber and the bypass path, (b) an optical dispersion compensating circuit with at least one of the unit connected in series, and (c) an optical attenuator provided, in the direction of an optical path, after the input optical switch or before the output optical switch of the optical dispersion compensating circuit.

What is claimed is:  
     
         1 . A variable optical dispersion compensating module comprising: 
 (a) an optical dispersion compensating unit having an input optical switch, an optical dispersion compensating fiber, connected to said optical switch, having a predetermined optical dispersion amount, a bypass path for bypassing said optical dispersion compensating fiber, and an output optical switch connected to said optical dispersion compensating fiber and said bypass path;    (b) an optical dispersion compensating circuit with at least one of said unit connected in series; and    (c) an optical attenuator provided between said input switch or said output switch of said optical dispersion compensating circuit and an optical connector for input or output.    
     
     
         2 . The variable optical dispersion compensating module according to  claim 1 , wherein a single optical switch is provided at a midpoint in said bypass path, which operates as said input optical switch and said output optical switch.  
     
     
         3 . The variable optical dispersion compensating module according to  claim 1 , wherein with respect to an optical dispersion amount of said optical dispersion compensating fiber composing said at least one of said optical dispersion compensating unit, when an optical dispersion amount of one optical dispersion compensating fiber is set at X, a negative optical dispersion amount of another optical dispersion compensating fiber is set at 2 N ×X (N is an integer ranging from 1 to j).  
     
     
         4 . The variable optical dispersion compensating module according to  claim 2 , wherein with respect to an optical dispersion amount of said optical dispersion compensating fiber composing said at least one of said optical dispersion compensating unit, when an optical dispersion amount of a specific optical dispersion compensating fiber is set at X, a negative optical dispersion amount of another optical dispersion compensating fiber is set at 2 N ×X (N is an integer ranging from 1 to j).  
     
     
         5 . The variable optical dispersion compensating module according to  claim 1 , further comprising: 
 a control device that controls switching of an optical path of each optical switch composing said at least one of said optical dispersion compensating unit and an attenuation of said optical attenuator so as to obtain a set predetermined optical dispersion amount and a set predetermined optical attenuation.    
     
     
         6 . The variable optical dispersion compensating module according to  claim 2 , further comprising: 
 a control device that controls switching of an optical path of each optical switch composing said at least one of said optical dispersion compensating unit and an attenuation of said optical attenuator so as to obtain a set predetermined optical dispersion amount and a set predetermined optical attenuation.    
     
     
         7 . The variable optical dispersion compensating module according to  claim 3 , further comprising: 
 a control device that controls switching of an optical path of each optical switch composing said at least one of said optical dispersion compensating unit and an attenuation of said optical attenuator so as to obtain a set predetermined optical dispersion amount and a set predetermined optical attenuation.    
     
     
         8 . The variable optical dispersion compensating module according to  claim 4 , further comprising: 
 a control device that controls switching of an optical path of each optical switch composing said at least one of said optical dispersion compensating unit and an attenuation of said optical attenuator so as to obtain a set predetermined optical dispersion amount and a set predetermined optical attenuation.    
     
     
         9 . The variable optical dispersion compensating module according to  claim 1 , wherein said optical dispersion compensating fiber composing said optical dispersion compensating unit is an optical fiber which is set for a predetermined dispersion amount and is wounded around a bobbin having a barrel portion on whose opposite ends are provided flange portions, one of which is provided with an insertion portion through which said optical fiber is passed.  
     
     
         10 . The variable optical dispersion compensating module according to  claim 1 , wherein said optical dispersion compensating fiber composing said optical dispersion compensating unit is an optical fiber which is set for a predetermined dispersion amount and is wounded around a bobbin having a barrel portion on whose opposite ends are provided flange portions, said barrel portion having a plurality of support poles and a plurality of expanding/shrinking axes to enable a diameter of said barrel portion to be expanded or shrunk.