Excitable interplay between lasing quantum dot states

Area of Science:

• Nonlinear Dynamics
• Quantum Dot Lasers
• Semiconductor Optics

Background:

• Optically injected semiconductor lasers are key for studying nonlinear dynamics and generating excitable pulses.
• Traditional models, like the Adler phase equation, describe excitable pulses arising from small perturbations of stable states, often with 2π phase rotation.

Purpose of the Study:

• To investigate a novel variation of type I excitability in a dual-state quantum dot laser system.
• To demonstrate a phenomenon not explicable by the standard Adler phase equation.
• To analyze the underlying physics, bifurcation conditions, and temporal evolution of these excitable pulses.

Main Methods:

• Experimental operation of a dual-state quantum dot laser, focusing emission on the excited state.
• Optical injection to activate and phase-lock the ground state while suppressing the excited state.
• Numerical analysis alongside experimental observations to understand system dynamics.

Main Results:

• Observed ground-state emission dropouts correlated with excited-state pulses near the phase-locking boundary.
• Demonstrated bounded phase rotations in the ground state due to interactions with the excited state.
• Confirmed that this excitability variation deviates from Adler model predictions.

Conclusions:

• Dual-state quantum dot lasers exhibit a unique type of excitability beyond the scope of the Adler phase equation.
• The interaction between ground and excited states leads to distinct pulse dynamics and phase behavior.
• Experimental and numerical findings show excellent agreement, validating the analysis of bifurcation and time evolution.