Quantifying stochasticity in the dynamics of delay-coupled semiconductor lasers via forbidden patterns

Area of Science:

• Nonlinear dynamics
• Quantum optics
• Laser physics

Background:

• Mutually coupled semiconductor lasers exhibit complex dynamics, including synchronization with lag.
• Irregular switching between leader and laggard roles is observed in such systems.
• Stochasticity plays a crucial role in understanding laser dynamics.

Purpose of the Study:

• To quantify the stochasticity in the dynamics of two mutually coupled semiconductor lasers.
• To analyze the switching dynamics between leader and laggard roles.
• To investigate the influence of pumping levels on stochasticity.

Main Methods:

• Quantification of stochasticity using forbidden patterns analysis of time series.
• Focus on a regime of synchronized dynamics with non-zero lag time.
• Comparison with dynamics of a single semiconductor laser subject to external optical feedback.

Main Results:

• The system operates in a stochastic regime.
• The level of stochasticity decreases as lasers are pumped further from their lasing threshold.
• Switching dynamics between leader and laggard roles are irregular.
• Observed behavior is analogous to a single laser shifting from low-frequency fluctuations to coherence collapse.

Conclusions:

• The stochastic nature of coupled laser dynamics is confirmed.
• Pumping level significantly influences the degree of stochasticity.
• The findings provide insights into the transition between different dynamical regimes in lasers.