Cavity linewidth engineering from tunneling induced transparency to Autler–Towns splitting

Cavity linewidth narrowing and broadening could be achieved simultaneously with quantum dot molecules under different conditions. In weak coupling regime and weak probe-field limit, the cavity linewidth is much narrowed because of tunneling induced transparency. But for strong coupling regime with relatively strong probe field, the cavity linewidth is broadened remarkably due to Autler–Towns splitting and enhanced self-Kerr nonlinearity. Analytical expression shows that the tunneling induces the large Kerr nonlinearity, and the enhanced anomalous dispersion will broaden the linewidth. The cavity linewidth could be engineered from nearly one-tenth to ten times of the empty cavity linewidth from simulation.