Detuning-enhanced sensitive detection of inter-dot tunneling with tunneling-induced gain

A large nonlinear gain spectrum induced by resonant tunneling is investigated and proposed to measure interdot tunneling. Resonant tunneling induces inherent coherence, which leads to constructive interference for the self-Kerr nonlinearity of a coupled quantum-dot system. The nonlinear gain increases dramatically at some frequency detuning. It inhibits the linear absorption and mainly contributes to the total gain of the system. In this case, the gain spectrum is about one order of magnitude larger than that on resonance. Analytical expression shows that the tunneling detuning dominates the response of nonlinear gain spectrum, so the gain peak is sensitive to the interdot tunneling changes. Numerical result indicates its sensitivity with relative large detuning is more than 10 times larger than the case on resonance. The scheme may be useful for designing photo-electric detection devices.