Electrically Tunable Orbital Coupling and Quantum Light Emission from O-Band Quantum Dot Molecules

We present the observation of electrically tunable quantum coupling of orbital states in individual InAs/InGaAs quantum dot molecules emitting in the telecom O-band (∼1.3 μ⁢m). By tuning the static electric field along the growth axis of the quantum dot (QD)-molecule, we observe pronounced anticrossings between excitonic transitions and determine the dependence of the interdot electron tunnel coupling on the interdot separation. As the electric field applied along the growth axis of the QD-molecules increases, positively charged exciton complexes sequentially emerge in the time-integrated emission spectra due to electrons escaping from the system while holes remain trapped. Moreover, for strong pumping, biexciton emission from the O-band molecules is identified. We demonstrate single-photon emission from the InAs/InGaAs QD-molecule emitting around 1.3 μ⁢m with a 𝑔⁽²⁾⁡(0)⁢ = ⁢0.017±0.002 and explore the impact of tuning orbital coupling on the second-order correlation function.