Acousto-optic filter and optical CDMA system using the same

Abstract

Provided are an acousto-optic filter and an optical code division multiple access (CDMA) system using the acousto-optic filter. The acousto-optic filter includes: an acousto-optic mode converter (AOMC) converting an optical signal of a specific optical frequency corresponding to a frequency of an electric signal of an optical signal of a first mode having a predetermined optical frequency band; and a mode stripper (MS) stripping an optical signal of the optical signal of the first mode that has been converted to a second mode.

1 . An acousto-optic filter used for an optical CDMA (code division multiple access) encoder, comprising: 
 an AOMC (acousto-optic mode converter) converting an optical signal having a specific optical frequency corresponding to a frequency of an electric signal into a second mode, wherein the optical signal is one of signals of a first mode having a predetermined optical frequency band; and    an MS (mode stripper) stripping the optical signal of the second mode.    
   
   
       2 . The acousto-optic filter of  claim 1 , wherein the AOMC receives an electric signal having a frequency of f 1 , and converts an optical signal having a specific optical frequency of ω 1  corresponding to the frequency of f 1  into a second mode optical signal having an optical frequency of ω 1 +f 1 .  
   
   
       3 . The acousto-optic filter of  claim 1 , wherein the AOMC simultaneously receives an electric signal having a plurality of frequencies and converts an optical signal having a specific optical frequency corresponding to the plurality of frequencies into a second mode.  
   
   
       4 . An acousto-optic filter used for an optical CDMA decoder, comprising: 
 an AOMC converting an optical signal having a specific optical frequency corresponding to a frequency of an electric signal into a second mode, wherein the optical signal is one of signals of a first mode having a predetermined optical frequency band; and    an MD (mode divider) outputting the optical signal of the first mode and the optical signal of the second mode to different ports, respectively.    
   
   
       5 . The acousto-optic filter of  claim 4 , wherein the AOMC receives an electric signal having a frequency of f 1  and converts an optical signal having a specific optical frequency of ω 1  into a second mode optical signal having an optical frequency of ω 1 +f 1 .  
   
   
       6 . An optical CDMA system using an acousto-optic filter, comprising: 
 at least one or more optical CDMA encoders outputting only an optical signal except an optical signal having a specific optical frequency corresponding to a frequency of an electric signal using an acousto-optic filter performing acousto-optic mode converting and mode stripping;    an optical coupler coupling optical signals output from a plurality of optical CDMA encoders; and    an optical CDMA decoder dividing the optical signals received from the optical coupler into a specific optical frequency corresponding to a predetermined frequency of an electric signal and outputting the divided optical signal using an acousto-optic filter performing acousto-optic mode converting and mode divider.    
   
   
       7 . The optical CDMA system of  claim 6 , wherein the optical CDMA encoder comprises: 
 a light source generating an optical signal of a first mode having a broadband; and    an acousto-optic filter converting an optical signal having an optical frequency corresponding to a predetermined frequency of the electric signal into a second mode and then outputting an optical signal except an optical signal of the second mode.    
   
   
       8 . The optical CDMA system of  claim 6 , wherein the optical CDMA decoder comprises: 
 an acousto-optic filter converting an optical signal having an optical frequency corresponding to a predetermined frequency of an electric signal into a second mode and then dividing and outputting the optical signal of the first mode and the optical signal of the second mode; and    a BPD (balanced photodetector) detecting the optical signals of the first and second modes and outputting the signal corresponding to the power difference between two light signals.