Optical modeling of superconducting nanowire single photon detectors using the transfer matrix method: publisher's note.

This publisher's note amends the Funding and Acknowledgment sections in Appl. Opt.57, 4872 (2018)APOPAI0003-693510.1364/AO.57.004872.

Optical modeling of superconducting nanowire single photon detectors using the transfer matrix method.

We present optical modeling of superconducting nanowire single photon detector devices using an analytical approach based on the transfer matrix method. We find that the optimal dielectric layer thicknesses vary slightly with the thickness and fill factor of the NbN layer and explore novel device geometries that can be described as a stack of thin films, such as devices on multilayered substrates, free-standing membranes, and optical fiber facets. In addition, the analytical results here show the importance of accounting for coherence correctly when an integrated cavity is included in the device structure and the relative insignificance of an anti-reflection coating in most cases.

Infrared transmissometer to measure the thickness of NbN thin films.

We present an optical setup that can be used to characterize the thicknesses of thin NbN films to screen samples for fabrication and to better model the performance of the resulting superconducting nanowire single photon detectors. The infrared transmissometer reported here is easy to use, gives results within minutes, and is nondestructive. Thus, the thickness measurement can be easily integrated into the workflow of deposition and characterization. Comparison to a similar visible-wavelength transmissometer is provided.

Eight-fold signal amplification of a superconducting nanowire single-photon detector using a multiple-avalanche architecture.

Superconducting nanowire avalanche single-photon detectors (SNAPs) with n parallel nanowires are advantageous over single-nanowire detectors because their output signal amplitude scales linearly with n. However, the SNAP architecture has not been viably demonstrated for n > 4. To increase n for larger signal amplification, we designed a multi-stage, successive-avalanche architecture which used nanowires, connected via choke inductors in a binary-tree layout. We demonstrated an avalanche detector with n = 8 parallel nanowires and achieved eight-fold signal amplification, with a timing jitter of 54 ps.

Low threshold room-temperature lasing of CdS nanowires.

The synthesis of CdS nanostructures (bands, wires, irregular structures) was investigated by systematic variation of temperature and gas pressure, to deduce a comprehensive growth phase diagram. The high quality nanowires were further investigated and show stoichiometric composition of CdS as well as a single-crystalline lattice without any evidence of extended defects. The luminescence of individual nanowires at low excitation shows a strong near band edge emission at 2.41 eV indicating a low point defect concentration. Sharp peaks evolve at higher laser power and finally dominate the luminescence spectrum. The power dependence of the spectrum clearly shows all the characteristics of amplified stimulated emission and lasing action in the nanowire cavity. A low threshold was determined as 10 kW cm(-2) for lasing at room temperature with a slope efficiency of 5-10% and a Q factor of up to 1200. The length and diameter relations necessary for lasing of individual nanowires was investigated.