Superconducting nanowire single-photon detectors （SNSPDs） with a composite optical structure composed of phase-grating and optical cavity structures are designed to enhance both the system detection efficiency and t...Superconducting nanowire single-photon detectors （SNSPDs） with a composite optical structure composed of phase-grating and optical cavity structures are designed to enhance both the system detection efficiency and the response bandwidth. Numerical simulation by the finite-difference time-domain method shows that the photon absorption capacity of SNSPDs with a composite optical structure can be enhanced significantly by adjusting the parameters of the phase-grating and optical cavity structures at multiple frequency bands. The absorption capacity of the superconducting nanowires reaches 70%, 72%, 60.73%, 61.7%, 41.2%, and 46.5% at wavelengths of 684, 850, 732, 924, 1256, and 1426nm, respectively. The use of a composite optical structure reduces the total filling factor of superconducting nanowires to only 0.25, decreases the kinetic inductance of SNSPDs, and improves the count rates.展开更多
A tunable superconducting half-wavelength coplanar waveguide resonator （CPWR） with Nb parallel nanowires - 300 nm in width embedded in the center conductor was designed, fabricated, and measured. The frequency shift...A tunable superconducting half-wavelength coplanar waveguide resonator （CPWR） with Nb parallel nanowires - 300 nm in width embedded in the center conductor was designed, fabricated, and measured. The frequency shift and the amplitude attenuation of the resonance peak under irradiation of 404-nm pulse laser were observed with different light powers at 4.2 K. The RF power supplied to such a CPWR can serve as current bias, which will affect the light response of the resonator.展开更多
Niobium nitride superconducting nanowire single-photon detectors were fabricated on thermally oxidized silicon substrates with large active areas of 30 μm × 30 μm. To achieve non-constricted detectors, we impro...Niobium nitride superconducting nanowire single-photon detectors were fabricated on thermally oxidized silicon substrates with large active areas of 30 μm × 30 μm. To achieve non-constricted detectors, we improved the film growth and electron beam lithography process to fabricate uniform 100-nm wide NbN nanowires with a fill factor of 50%. The devices showed 72.4% system detection efficiency （SDE） at 100-Hz dark count rate （DCR） and 74-ps timing jitter, measured at the fiber communication wavelength of 1550 nm. The highest SDE which is 81.2% when the DCR is ~ 700 c/s appears at the wavelength of 1650 nm.展开更多
We report on fractal-featured square and ring-shaped apertures with a Sierpinski carpet pattern(SCP)on metallic and superconducting NbN films.Multiple extraordinary terahertz(THz)transmission peaks are studied in the ...We report on fractal-featured square and ring-shaped apertures with a Sierpinski carpet pattern(SCP)on metallic and superconducting NbN films.Multiple extraordinary terahertz(THz)transmission peaks are studied in the transmission spectra using both THz time-domain spectroscopy and numerical simulation.The characteristic transmission peaks are found to be associated with the interaction of surface plasmon polaritons(SPPs)and localized surface plasmons(LSPs)for ring-shaped apertures.The effect of LSPs is less remarkable in the square apertures.For the superconducting NbN film,when the temperature is slightly lower than the critical transition temperature T_(c),the peak magnitude of SPP resonances is most prominent due to the non-monotonic temperature dependence of kinetic inductance.These results provide a new way to design compact and efficient THz devices.展开更多
基金Supported by the National Basic Research Program of China under Grant Nos 2011CBA00100 and 2011CBA00200the National Natural Science Foundation of China under Grant Nos 11227904 and 61101012+1 种基金the National High-Technology ResearchDevelopment Program of China under Grant No 2011AA010204the Jiangsu Key Laboratory of Advanced Techniques for Manipulating Electromagnetic Waves
文摘Superconducting nanowire single-photon detectors （SNSPDs） with a composite optical structure composed of phase-grating and optical cavity structures are designed to enhance both the system detection efficiency and the response bandwidth. Numerical simulation by the finite-difference time-domain method shows that the photon absorption capacity of SNSPDs with a composite optical structure can be enhanced significantly by adjusting the parameters of the phase-grating and optical cavity structures at multiple frequency bands. The absorption capacity of the superconducting nanowires reaches 70%, 72%, 60.73%, 61.7%, 41.2%, and 46.5% at wavelengths of 684, 850, 732, 924, 1256, and 1426nm, respectively. The use of a composite optical structure reduces the total filling factor of superconducting nanowires to only 0.25, decreases the kinetic inductance of SNSPDs, and improves the count rates.
基金Project supported by the National Basic Research Program of China(Grant Nos.2011CB922104 and 2011CBA00200)the National Natural Science Foundation of China(Grant No.11474154)+1 种基金the Jiangsu Natural Science Fund for Distinguished Young Scholars(Grant No.BK2012013)a Doctoral Program(Grant No.20120091110030)
文摘A tunable superconducting half-wavelength coplanar waveguide resonator （CPWR） with Nb parallel nanowires - 300 nm in width embedded in the center conductor was designed, fabricated, and measured. The frequency shift and the amplitude attenuation of the resonance peak under irradiation of 404-nm pulse laser were observed with different light powers at 4.2 K. The RF power supplied to such a CPWR can serve as current bias, which will affect the light response of the resonator.
文摘Niobium nitride superconducting nanowire single-photon detectors were fabricated on thermally oxidized silicon substrates with large active areas of 30 μm × 30 μm. To achieve non-constricted detectors, we improved the film growth and electron beam lithography process to fabricate uniform 100-nm wide NbN nanowires with a fill factor of 50%. The devices showed 72.4% system detection efficiency （SDE） at 100-Hz dark count rate （DCR） and 74-ps timing jitter, measured at the fiber communication wavelength of 1550 nm. The highest SDE which is 81.2% when the DCR is ~ 700 c/s appears at the wavelength of 1650 nm.
基金Supported by the National Basic Research Program of China(Nos 2011CBA00107,2011CBA00202)the National Natural Science Foundation of China under Grant Nos 61071009,61027008,11104110+1 种基金the Specialized Research Fund for Doctoral Program of Higher Education(20090091110040)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘We report on fractal-featured square and ring-shaped apertures with a Sierpinski carpet pattern(SCP)on metallic and superconducting NbN films.Multiple extraordinary terahertz(THz)transmission peaks are studied in the transmission spectra using both THz time-domain spectroscopy and numerical simulation.The characteristic transmission peaks are found to be associated with the interaction of surface plasmon polaritons(SPPs)and localized surface plasmons(LSPs)for ring-shaped apertures.The effect of LSPs is less remarkable in the square apertures.For the superconducting NbN film,when the temperature is slightly lower than the critical transition temperature T_(c),the peak magnitude of SPP resonances is most prominent due to the non-monotonic temperature dependence of kinetic inductance.These results provide a new way to design compact and efficient THz devices.
