InGaAs/InP SPAD detecting single photons at 1550 nm with up to 50% efficiency and low noise

We present an InGaAs/InP single-photon avalanche diode (SPAD) with high photon detection efficiency and low noise for fiber-based quantum optics applications. Compared to previous InGaAs/InP SPADs, the InGaAs absorption layer is thicker, to maximize the quantum efficiency. The double zinc diffusion has been adjusted to avoid premature edge breakdown, with the help of a guard ring structure. Our detector achieves a photon detection efficiency up to 50% at 1550 nm, with a dark count rate of 20 kcps and a timing jitter of ∼ 70 ps (FWHM) at 225 K. Alternatively, it features a photon detection efficiency of 37% at 1550 nm, with a dark count rate of just 3 kcps and a timing jitter of ∼ 100 ps (FWHM). When combined with a custom integrated circuit, afterpulsing probability is as low as few percent with a gating frequency of 1 MHz and hold-off time of few microseconds at 225 K, allowing to achieve a photon count rate of almost 1 Mcps.