Suppression of relaxation oscillation in light output of injection lasers by electrical resonance circuit

It is shown that relaxation oscillation in the light outputs of injection lasers can be suppressed by an external electrical circuit. This method can be applicable to high-speed pulse modulation. For this purpose, an electrical resonant circuit connected to the laser diode (LD) and tuned to the relaxation oscillation is considered as an example. Frequency response of direct modulation and the device-transient characteristics are analyzed. These results were verified experimentally. A brief discussion on the upper limit of the repetition frequency of pulse modulation is given and it is shown theoretically that stable pulse modulation of an LD up to a few Gbit/s may be obtained by applying this method.