Design optimization for bright electrically-driven quantum dot single-photon sources emitting in telecom O-band.

A combination of advanced light engineering concepts enables a substantial improvement in photon extraction efficiency of micro-cavity-based single-photon sources in the telecom O-band at ∼1.3 µm. We employ a broadband bottom distributed Bragg reflector (DBR) and a top DBR formed in a dielectric micropillar with an additional circular Bragg grating in the lateral plane. This device design includes a doped layer in pin-configuration to allow for electric carrier injection. It provides broadband (∼8-10 nm) emission enhancement with an overall photon-extraction efficiency of ∼83% into the upper hemisphere and photon-extraction efficiency of ∼79% within numerical aperture NA=0.7. The efficiency of photon coupling to a single-mode fiber reaches 11% for SMF28 fiber (with NA=0.12), exceeds 22% for 980HP fiber (with NA=0.2) and reaches ∼40% for HNA fiber (with NA=0.42) as demonstrated by 3D finite-difference time-domain modeling.