Superconducting nanowire single-photon detector working in two wavebands

Abstract

The invention discloses a superconducting nanowire single-photon detector working in two wavebands. The superconducting nanowire single-photon detector comprises a four-stage cascaded fractal photosensitive region structure of which the photosensitive region line width is preset nanometers; a cavity structure consisting of a gold layer, a first silicon dioxide layer, a silicon layer, a second silicon dioxide layer, a fractal nanowire layer, a third silicon dioxide layer and a silicon substrate layer is constructed in sequence from top to bottom; and the thicknesses of the first silicon dioxidelayer, the silicon layer and the second silicon dioxide layer is regulated and controlled until the resonance wavelength shifts to two wavebands needing absorption enhancement. According to the invention, the structure of the narrow-band optical cavity is improved, so that the photon absorption is enhanced under double wavebands; and the internal quantum efficiency of the device and the signal-to-noise ratio of a detection signal are improved by utilizing a four-stage cascaded narrow-linewidth fractal nanowire structure.

Description

technical field [0001] The invention relates to the field of superconducting nanowire single photon detectors, in particular to a superconducting nanowire single photon detector working in dual bands. Background technique [0002] Superconducting nanowire single photon detectors (SNSPDs) have a variety of excellent properties in the field of single photon detection: high efficiency (93% system detection efficiency at 1550 nm wavelength), low time domain jitter (less than 20 picoseconds), low dark mark Count rate (1 per second). Therefore, SNSPDs have been widely used in the testing of the basic principles of quantum optics, quantum key distribution, and space-ground long-distance communication. [0003] Since the energy of a single photon (on the order of 1 electron volt) is much greater than the band gap energy (on the order of millielectron volts) of superconducting materials such as niobium nitride and titanium niobium nitride, SNSPDs themselves have a wide range from ul...

AI Technical Summary

Problems solved by technology

In order to enhance optical absorption at specific wavelengths in the above applications, narrow-band optical resonators need to be added to the surface of SNSPDs, but narrow-band optical resonators will also inhibit optical absorption at other wavelengths, thus limiting the application of SNSPDs in multiple bands. Such as multi-wavelength ranging, multi-spectral imaging, etc.

[0004] At present, the solution to achieve high system detection efficiency in multiple bands is to use a double-layer distributed Bragg mirror structure to achieve absorption efficiencies greater than 80% at 1064 nanometers, 1300 nanometers, and 1550 nanometers on a circular nanowire structure. The structure requires ion beam-assisted sputtering of 20 layers of periodic structures with nanometer precision requirements, and the processing is more complicated

[0005] In addition, since the photosensitive area in this scheme adopts a circular nanowire structure with a line width of 80 nanometers, the internal quantum efficiency has not been fully saturated at a wavelength of 1550 nanometers, which limits the detection efficiency of the system at long wavelengths.

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