Hello Neha,
You may check any example in the advanced modulation system directory that can be found at the following address for more information on coherent receivers. Also, there is a component in OptiSystem called “Optical Coherent QAM Receiver” that you may check its data sheet for more information on the structure of a coherent receiver. The data sheet can be accessed from the help button in the component property.
C:\Users\USERNAME\Documents\OptiSystem 16.0 Samples\Advanced modulation systems\QAM systems\16 QAM\
regards,
Ahmad