Continuous current-injected waveforms shaping for suppressing relaxation oscillations of direct modulation based on equivalent circuit model

An improved technique of continuous shaping current-injected waveforms based on the single-mode rate equations is proposed to suppress relaxation oscillations (ROs) from direct modulation of distributed feedback laser (DFB). The signal expression of shaping current is deduced theoretically from the dependence of DFB desired output waveforms in detail, and the specific parameters derivation of the different polynomial degree is also discussed necessarily. Furthermore, a polynomial p-function with inverse operation is adopted to construct the Fourier series corresponding to injection current waveform signal. The equivalent circuit model with DFB phenomenological description is injected into shaping current signal to verity the proposed validity by evaluating the static and dynamic characteristics. The simulation results of the optimized shaping signal show the good agreement with the desired output pulse including rising and falling edge and suppress the ROs amplitude dramatically at the two jump edges. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

This paper proposes an improved technique of continuous shaping current-injected waveforms to suppress relaxation oscillations (ROs) in distributed feedback lasers (DFB). The signal expression of shaping current is deduced theoretically, and the specific parameters derivation of different polynomial degrees is discussed. The simulation results show that the optimized shaping signal achieves good agreement with the desired output pulse and effectively suppresses ROs at the jump edges.