Output characteristics of RF-modulated laser diodes

The authors analyze theoretically and experimentally the output characteristics of periodically current-modulated laser diodes with an without an external resonator. It is shown that nonlinear output characteristics can be obtained without introducing an intensity-dependent gain saturation. The total emitted intensity per modulation period shows, as a function of the DC part of the pump current, a characteristic saturation behavior each time before the number of emitted pulses per modulation period increases. It is shown that a similar behavior for the light-current characteristics is obtained for the mode-locked laser in an external cavity and the solitary laser, even though the mechanisms which yield the multiple pulse emission in both cases are rather different