Continuous current-injected waveforms shaping for suppressing relaxation oscillations of direct modulation based on...

Area of Science:

• Photonics
• Semiconductor Lasers
• Optical Engineering

Background:

• Direct modulation of distributed feedback (DFB) lasers is crucial for optical communication systems.
• Relaxation oscillations (ROs) are inherent phenomena that degrade the performance of directly modulated DFB lasers.
• Existing methods for suppressing ROs often involve complex circuitry or compromise signal quality.

Purpose of the Study:

• To propose and validate an improved technique for continuous shaping current-injected waveforms.
• To effectively suppress relaxation oscillations (ROs) in directly modulated DFB lasers.
• To achieve desired output waveforms with sharp rising and falling edges.

Main Methods:

• Utilizing single-mode rate equations to derive the signal expression for shaping current.
• Employing a polynomial p-function with inverse operation to construct the Fourier series for the injection current waveform.
• Developing an equivalent circuit model with DFB phenomenological description for validation.
• Evaluating static and dynamic characteristics through simulation.

Main Results:

• The proposed shaping current signal effectively suppresses RO amplitude at jump edges.
• Simulation results demonstrate good agreement between the optimized shaping signal and desired output pulse characteristics.
• The technique successfully controls both rising and falling edges of the output waveform.

Conclusions:

• The developed continuous shaping current-injection technique offers a viable solution for suppressing ROs in DFB lasers.
• This method enhances the dynamic performance and output waveform quality of directly modulated DFB lasers.
• The findings contribute to the advancement of high-speed optical modulation technologies.