Large area single photon detectors based on parallel configuration NbN nanowires

Abstract

The authors present superconducting single photon detectors (SSPDs) based on parallel nanostrips with an area up to 40 × 40 μm2. The SSPDs presented here are based on 100 nm wide ultrathin NbN nanostrips with a filling factor of 40%. The devices are fabricated by extending the standard electron beam lithography (EBL) patterning process to those densely structured large areas. By a thorough characterization it is shown that the electrical properties of the parallel SSPDs are comparable with those of smaller devices, as expected, proving in this way that the extended EBL process results in uniform nanostrips also in large area detectors. Furthermore, the estimated maximum count rate of the 40 × 40 μm2 parallel SSPDs was 33 MHz, showing that the parallel nanostrip configuration is much faster when compared with standard meandered serial SSPDs. The successful extension of parallel SSPDs to a large area coverage opens a new route to the use of such detectors also with multimode fibers

Multimode Fiber Coupled Superconductor Nanowire Single-Photon Detector

“…In addition, the fabrication difficulty increases exponentially as the detection area increases. Therefore the maximum detection area reported thus far is only 40 Â 40 m 2 [20] for single nanowire, which is smaller than the core diameter (50 m) of standard multi-mode fibers. Thus, no multi-mode fiber coupled SNSPD with single nanowire has been reported previously.…”

“…Many attempts [18]- [20] tried to increase the detection area for developing multi-mode fibercoupled SNSPDs. A large active area benefits optical coupling but produces high kinetic inductance, which inevitably degrades the repetition rate of SNSPDs.…”

Large-sensitive-area superconducting nanowire single-photon detector at 850 nm with high detection efficiency

“…To enhance the absorption at 850 nm, a specific substrate with a one-dimensional (1-D) photonic crystal (PC) comprising dielectric films are used. The sensitive area diameter is 50 m, which to the best of our knowledge, has the largest sensitive area for a single pixel SNSPD [20][21][22][23]. By optimizing the linewidth and the spacing, the best device showed a maximal DE of 82% and DE of 78% at DCR of 100 Hz, which have prospective applications in free space satellite-ground quantum communication.…”

Dual-lens beam compression for optical coupling in superconducting nanowire single-photon detectors

“…Several research groups have reported SNSPDs with a large detection area [15][16][17]. However, fabricating an SNSPD with a large detection area increases the kinetic inductance [18], which determines the repetition rate of the SNSPD, and increases the difficulty encountered during microfabrication.…”