Stability and nonlinear dynamics of directly modulated high-speed long-wavelength laser diodes

Investigation and modeling of the effect of recombination and gain nonlinearities caused both by saturation and nonlinear dependence on carrier concentration on modulation response of high-speed long-wavelength bulk semiconductor lasers under moderate and strong modulation are presented. It is shown that increase in the injection current modulation depth leads to the fast distortion of harmonic response which pattern is greatly dependent on modulation frequency value. For a modulation amplitude comparable with the steady one the laser diode dynamics exhibits bifurcation of period doubling that can result in chaotic behavior.