Dear Ravil Thanks alot for your reply.
Actually in my project i am using 3 laser i-e 1,2,3 with frequency 193.2, 193.21 and 193.14 respectively.
The difference between laser 1 and 3 gives upper lower frequency spectrum 60GHz and Laser 2 and 3 gives upper frequency spectrum 75GHz.In this case which Extrinction ratio should i selecte i-e 1dB,2dB,3dB etc.As Extrinction Ratio =P1/Po
Please check the snap shot
Best Regards