Nanowire single-photon detector with an integrated optical cavity and anti-reflection coating

Abstract

We have fabricated and tested superconducting single-photon detectors and demonstrated detection efficiencies of 57% at 1550-nm wavelength and 67% at 1064 nm. In addition to the peak detection efficiency, a median detection efficiency of 47.7% was measured over 132 devices at 1550 nm. These measurements were made at 1.8K, with each device biased to 97.5% of its critical current. The high detection efficiencies resulted from the addition of an optical cavity and anti-reflection coating to a nanowire photodetector, creating an integrated nanoelectrophotonic device with enhanced performance relative to the original device. Here, the testing apparatus and the fabrication process are presented. The detection efficiency of devices before and after the addition of optical elements is also reported.

Electrothermal feedback in superconducting nanowire single-photon detectors

“…For R S = 0, these devices had similar performance to those in Ref. 3. Panels ͑c͒ and ͑d͒ show averaged pulse shapes for devices with R S =0,250⍀, respectively.…”

“…DOI: 10.1103/PhysRevB.79.100509 PACS number͑s͒: 85.25.Oj, 74.78.Ϫw, 85.60.Gz Superconducting nanowire single-photon detectors ͑SNSPDs͒ combine high speed, high detection efficiency ͑DE͒ over a wide range of wavelengths, and low dark counts. [1][2][3][4] Of particular importance is their high singlephoton timing resolution of ϳ30 ps, 4 which permits extremely high data rates in photon-counting communications applications. 5,6 Full use of this electrical bandwidth is limited, however, by the fact that the maximum count rates of these devices are much smaller ͑a few hundred MHz for 10 m 2 active area and decreasing as the area is increased 2 ͒, limited by their large kinetic inductance and the input impedance of the readout circuit.…”

“…Patterning of the NbN was then performed with e-beam lithography. 3 Devices were tested in a cryogenic probing station at 2 K as described in Refs. 2 and 3.…”

Nanowire superconducting single-photon detectors on GaAs for integrated quantum photonic applications

“…3 we can estimate a NEP ͑noise equivalent power͒, 16 ranging from 1.3ϫ 10 −17 W / ͱ Hz at 0.91I c ͑corre-sponding to a QE= 5.1%͒ to 1.3ϫ 10 −16 W / ͱ Hz at 0.99I c ͑corresponding to a QE= 18.3%͒. The fact that the peak QE is lower than the theoretical absorptance of 83% and than previously reported QE values for microcavity SSPDs on sapphire 17 and silica 18 is ascribed to the limited internal quantum efficiency ͑ is the probability that a photocreated hotspot produces a transition to the resistive state͒. Lower measurement temperatures and further fine tuning of the film thickness and deposition conditions should enable reaching a QE value equal to the absorptance.…”

Universal scaling of the critical temperature for thin films near the superconducting-to-insulating transition

“…We chose sputtered NbN as the material for this study for four main reasons: (a) It is widely researched, and experimental data collected for different growth methods and conditions are available; (b) there are contradicting reports about which of the existing models describes the T c suppression in NbN films-for instance, Kang et al [18] proposed that T c is suppressed due to the quantum size effect, Wang et al [17] suggested that the suppression follows Finkel'stein's model [9], Semenov et al [19] determined that the suppression is governed by the proximity effect, and Koushik et al [39] argued that the transition is of a BKT type; (c) the relatively high T c of NbN (16 K for a bulk NbN [40]) assists the experimental investigation; and (d) its properties make it useful for photodetectors [34,36,41,42].…”