InGaAs/InP single-photon detectors with 60% detection efficiency at 1550 nm

InGaAs/InP single-photon detectors (SPDs) are widely used for near-infrared photon counting in practical applications. Photon detection efficiency (PDE) is one of the most important parameters for SPD characterization, and therefore, increasing PDE consistently plays a central role in both industrial development and academic research. Here, we present the implementation of high-frequency gating InGaAs/InP SPDs with a PDE as high as 60% at 1550 nm. On one hand, we optimize the structure design and device fabrication of InGaAs/InP single-photon avalanche diodes with an additional dielectric-metal reflection layer to relatively increase the absorption efficiency of incident photons by ∼20%. On the other hand, we develop a monolithic readout circuit of weak avalanche extraction to minimize the parasitic capacitance for the suppression of the afterpulsing effect. With 1.25 GHz sine wave gating and optimized gate amplitude and operation temperature, the SPD is characterized to reach a PDE of 60% with a dark count rate (DCR) of 340 kcps. For practical use, given 3 kcps DCR as a reference, the PDE reaches ∼40% PDE with an afterpulse probability of 5.5%, which can significantly improve the performance for the near-infrared SPD-based applications.