Filtering directly modulated laser diode pulses with a Mach-Zehnder optical delay interferometer

An improvement in the waveform of 10 Gbit/s pulses from a directly modulated DFB laser by the use of an optical delay interferometer (ODI) is demonstrated. The insertion of this device in the transmitter suppresses amplitude overshoot and enhances the extinction ratio by 2.7 dB. It is shown that the transmission distance is increased by the addition of the ODI.