Quantum-Dot-Based Single-Photon Detection with Solid-Immersion-Lens Integration

Quantum-dot, optically gated, field-effect transistors (QDOGFETs) have been shown to exhibit photon-number-resolving capabilities and are promising devices for future quantum networks; however, with their mm-sized active areas, it has proven difficult to efficiently couple light into them. Here, we demonstrate how a high-index, cubic zirconia, solid-immersion lens (SIL) can be used to improve the free-space coupling of light into QDOGFET single-photon detectors. Wewill show how SIL-integration can be used to reduce the loss associated with photons missing the active area of the QDOGFET and how it can be used to direct the photons to the quantum dots that exhibit the largest and most uniform responses. While the former improves the overall detection efficiency of the system, the latter ensures that the detector is operating with its optimal sensitivity and photon-number resolution. Our presentation will include the results of measurements where statistical analysis of the detected photons is employed to evaluate the performance of SIL-capped detectors and to produce the response maps that we use to identify the optical seed point of photons.