Fiber communication systems typically employ some form of digital communication technique that requires
the laser to be switched ON to transmit a digital 1 and switched OFF to transmit a digital 0. To transmit a digital 0
the laser is biased slightly above the threshold where the optical output power will be low. Conversely, to generate a
digital 1, a current pulse is applied to the laser so that its optical output power will jump significantly as shown in
figure 7.