Module 19 : WDM Components
Lecture     : WDM Components - II
 

In the figure, the circulator OC-1 whose ports are numbered from 1 to 4 is used to transform the wavelengths $ \lambda_1, \lambda_3, \lambda_5 , \lambda_7$from west to east and the circulator OC-2 to transform $ \lambda_2, \lambda_4, \lambda_6 , \lambda_8$from east to west. The second circulator OC-2 is used to drop $ \lambda_1$and $ \lambda_2$at port 8 and add $ \lambda_1^\prime$and $ \lambda_2^\prime$at port 5. Signals $ \lambda_1, \lambda_3, \lambda_5 , \lambda_7$enter port 1 of OC-1 and leave from port 2. All wavelengths other than $ \lambda_1$are reflected by FBG, re-enter port 2 and leave OC-1 through port 3 travelling east. $ \lambda_1$enters port 6 of OC-2, travels to port-7, reflected by FBG to re-enter port 7, travels to port 8 and is dropped there. In a similar way $ \lambda_2$is dropped at port 8 while $ \lambda_4,\lambda_6, \lambda_8$travelling towards west leave OC-1 through port 1.
Wavelengths $ \lambda_1^\prime$and $ \lambda_2^\prime$, added at port 5, respectively leave OC-1 through ports 3 and 1.

  Optical Cross Connects (OXC)
  Cross connects are essential components of any communication system. Optical cross connects (OXC) are essentially switches which connect any of the input ports to any of the output ports. In the hybrid version of optical switches, switching was done by first converting optical signal to electrical signals, do switching electronically and then reconvert the electrical signals to optical signals. An OXC is an all optical switch which work entirely at photonic level. Because of the high cost of OXCs, hybrid switches are still used today. However, in large bandwidth applications, OXCs are more effective.
 
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