Optical communication system and optical transmitting apparatus for the same

Abstract

An optical communication system includes an optical transmission apparatus and an optical receiving apparatus. The optical transmission apparatus includes an input port to receive an electric signal, a noise generator to generate noise, a transmission signal generator to generate a transmission signal by multiplexing the noise with the electric signal, and an electric/optical converter to convert the transmission signal into an optical signal and send out the optical signal to an optical transmission path. The optical receiving apparatus connected to the optical transmission apparatus via the optical transmission path and receiving the optical signal through the optical transmission path. The optical receiving apparatus includes an optical/electric converter to convert the optical signal received through the optical transmission path into a receive electric signal and a receiving filter to remove the noise from the receive electric signal.

1 . An optical communication system comprising: 
 an optical transmission apparatus comprising:    an input port to receive an electric signal;    a noise generator to generate noise;    a transmission signal generator to generate a transmission signal by multiplexing the noise with the electric signal; and    an electric/optical converter to convert the transmission signal into an optical signal and send out the optical signal to an optical transmission path; and    an optical receiving apparatus connected to the optical transmission apparatus via the optical transmission path and receiving the optical signal through the optical transmission path, the optical receiving apparatus comprising:    an optical/electric converter to convert the optical signal received through the optical transmission path into a receive electric signal; and    a receiving filter to remove the noise from the receive electric signal.    
   
   
       2 . The optical communication system according to  claim 1 , wherein; 
 the transmission signal generator comprises:    a multiplexer to multiplex the noise and the electric signal for producing the transmission signal; and    a drive amplifier to amplify the transmission signal of the multiplexer.    
   
   
       3 . The optical communication system according to  claim 1 , wherein; 
 the transmission signal generator comprises:    a drive amplifier to amplify the electric signal; and    a multiplexer to multiplex the noise and the amplified electric signal for producing the transmission signal.    
   
   
       4 . The optical communication system according to  claim 1 , wherein; 
 the optical transmission apparatus further comprises a transmission filter, which possesses a suppressing characteristic in a frequency band of the electric signal, and passes through the noise; and    the transmission signal generator produces the transmission signal by multiplexing the noise passed through the transmission filter and the electric signal.    
   
   
       5 . The optical communication system according to  claim 1 , wherein; 
 the optical transmission apparatus further comprises a transmission filter, which possesses a passing characteristic in a frequency band different from a frequency band of the electric signal, and passes through the noise; and    the transmission signal generator produces the transmission signal by multiplexing the noise passed through the transmission filter and the electric signal.    
   
   
       6 . The optical communication system according to  claim 5 , wherein the transmission filter possesses a passing characteristic in a frequency band lower than the frequency band of the electric signal.  
   
   
       7 . The optical communication system according to  claim 1 , wherein; 
 the noise generator generates white noise over a range from a baseband to a frequency higher than the frequency band of the electric signal;    the transmission signal generator produces a transmission signal by multiplexing the white noise and the electric signal.    
   
   
       8 . An optical transmission apparatus used for an optical communication system in which an optical signal modulated by an electric signal is transmitted via an optical transmission path, 
 the optical transmission apparatus comprising:    a noise generator to generate noise;    a transmission signal generator to produce a transmission signal by multiplexing the noise and the electric signal; and    an electric/optical converter to convert the transmission signal into the optical signal and send out the optical signal to the optical transmission path.    
   
   
       9 . The optical transmission apparatus according to  claim 8 , wherein the transmission signal generator comprises: 
 a multiplexer to multiplex the noise and the electric signal produce the transmission signal; and    a drive amplifier to amplify the transmission signal of the multiplexer.    
   
   
       10 . The optical transmission apparatus according to  claim 8 , wherein the transmission signal generator comprises: 
 a drive amplifier to amplify the electric signal, and    a multiplexer to multiplex the noise and the amplified electric signal to produce the transmission signal.    
   
   
       11 . The optical transmission apparatus according to  claim 8 , which further comprises a transmission filter possessing a suppressing characteristic in a frequency band of the electric signal, and passing through the noise; and wherein 
 the transmission signal generator produces the transmission signal by multiplexing the noise passed through the transmission filter and the electric signal.    
   
   
       12 . The optical transmission apparatus according to  claim 8 , which further comprises a transmission filter possessing a passing characteristic in a frequency band different from a frequency band of the electric signal, and passing through the noise; and wherein 
 the transmission signal generator produces the transmission signal by multiplexing the noise passed through the transmission filter and the electric signal.    
   
   
       13 . The optical transmission apparatus according to  claim 12 , wherein; 
 the transmission filter possesses a passing characteristic in a frequency band lower than the frequency band of the electric signal.    
   
   
       14 . The optical transmission apparatus according to  claim 8 , wherein; 
 the noise generator generates white noise over a frequency range from the baseband to a frequency higher than the frequency band of the electric signal; and    the transmission signal generator produces the transmission signal by multiplexing the white noise and the electric signal.