Pulse-shaping to reduce the chirping effects of DFB laser diodes and pulse broadening

摘要

In this thesis, a computer simulation has been done to evaluate the wavelength chirping and pulse broadening effects induced by the direct intensity modulation using Distributed Feedback (DFB) laser diodes. In the simulation, a DFB laser diode is driven by either square wave current pulses or pulses with a small current Step in the Leading Edge (SLE). A comparative study is performed to justify the effectiveness of using SLE waves in modulation to reduce wavelength chirping and pulse broadening. Numerical results from the single-mode rate equations show that the SLE wave modulation reduces the wavelength chirping and pulse broadening by a factor of 2. The optimal SLE pulse has a prepulse duration of 0.15 ns and a prepulse current level of 70.0 mA.