Hi Zulkarnain…
As far as speed is concerned, it is one of the important parameter to be considered about the laser to be used. The speed of operation is required to be high as input data frequency is high, so the laser should be able to switch between states immediately.
No the extinction ratio is the ration of the power level corresponding to “MARK” to the power level corresponding to “SPACE”.
ER=P1/P0…………P1 is for MARK and P2 for SPACE,,,
The value of ER should be high for easy recognition of MARK and SPACE,,,,
Hope it helps you to some extent
best regards.,