Wavelength division multiplexing passive optical network system

Abstract

Disclosed is a wavelength division multiplexing passive optical network (WDM PON) system in which an optical signal outputted from a central office is injected into a Fabry-Perot laser diode (F-P LD) as the light source of an optical network unit, so that the output wavelength of the optical network unit is injection-locked at the same wavelength as that of the optical signal outputted from the central office, thereby enabling the optical network unit to output an optical signal having the same wavelength as that of the optical signal outputted from the central office. In accordance with this system, it is possible to transmit and receive forward and backward data at the same wavelength by the unit of channels. Since inexpensive F-P LDs are used as respective light sources of the central office and optical network units, it is possible to efficiently and economically implement a WDM PON system.

1 - 9 . (canceled)  
     
     
         10 . A ring type wavelength division multiplexing passive optical network (WDM PON) system comprising: 
 a central office including a first multiplexer/demultiplexer adapted to perform a multiplexing/demultiplexing operation for normal signals to be used in a normal state, and a second multiplexer/demultiplexer adapted to perform a multiplexing/demultiplexing operation self-healing signals to be used for a self-healing purpose, the central office generating optical signals of N different wavelengths, each of the first and second multiplexers/demultiplexers multiplexing the generated optical signals, and transmitting the resultant multiplexed optical signal to optical network units through a single optical fiber, while demultiplexing a multiplexed optical signal received from the single optical fiber, thereby detecting data generated from the optical network units; and    remote nodes respectively including bi-directional add/drop devices connected to respective optical network units, the remote nodes establishing a ring type distribution network in cooperation with the first and second multiplexers/demultiplexers of the central office, each of the bi-directional add/drop devices including first and second WDM filters respectively having opposite signal travel directions, the first WDM filter performing an add/drop operation for associated ones of the normal signals, the second WDM filter performing an add/drop operation for associated ones of the self-healing signals.    
     
     
         11 . The ring type WDM PON system according to  claim 10 , wherein the first multiplexer/demultiplexer of the central office performs the same multiplexing/demultiplexing operation for the normal signals in both cases in which the normal signals travel in forward and backward directions, respectively.  
     
     
         12 . The ring type WDM PON system according to  claim 10 , wherein the first multiplexer/demultiplexer of the central office performs the same multiplexing/demultiplexing operation for the self-healing signals in both cases in which the self-healing signals travel in forward and backward directions, respectively.  
     
     
         13 . The ring type WDM PON system according to  claim 10 , wherein each WDM filter included in each bi-directional add/drop device drops an optical signal having a selected wavelength from optical signals of N different wavelengths inputted to an input port thereof, to a drop port thereof in accordance with a reflection operation thereof, and transmits the optical signals of the remaining wavelengths through an output port thereof, while reversibly reflecting an optical signal having the selected wavelength inputted to the drop port toward the input port to output the reflected optical signal to the central office.  
     
     
         14 - 16 . (canceled)