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Increasing the detection efficiency(DE)is a hot issue in the development of the superconducting nanowire single photon detector(SNSPD).In this work,a cavity-integrated structure coupled to the SNSPD is used to enhance the light absorption of nanowire.Ultra-thin Nb films are successfully prepared by magnetron sputtering,which are used to fabricate Nb/Al SNSPD with the curve of 100 nm and the square area of 4×4μm~2 by sputtering and the lift-off method.To characterize the optical and electrical performance of the cavity-integrated SNSPD,a reliable cryogenic research system is built up based on a He~3 system.To satisfy the need of light coupling,a packaging structure with collimator is conducted.Both DE and the dark count rates increase with I_b.It is also found that the DE of SNSPD with cavities can be up to 0.17% at the temperature of 0.7 K under the infrared light of 1550 nm,which is obviously higher than that of the SNSPD directly fabricated upon silicon without any cavity structure.
Increasing the detection efficiency (DE) is a hot issue in the development of the superconducting nanowire single photon detector (SNSPD) .In this work, a cavity-integrated structure coupled to the SNSPD is used to enhance the light absorption of nanowire. Ultra- thin Nb films are successfully prepared by magnetron sputtering, which are used to fabricate Nb / Al SNSPD with the curve of 100 nm and the square area of 4 × 4 μm ~ 2 by sputtering and the lift-off method. Character character the optical and electrical performance of the cavity-integrated SNSPD, a reliable cryogenic research system is built based on a He ~ 3 system. To satisfy the need of light coupling, a packaging structure with collimator is studied. Since DE and the dark count rates increase with I_b .It also also found that the DE of SNSPD with cavities can be up to 0.17% at the temperature of 0.7 K under the infrared light of 1550 nm, which is obviously higher than that of the SNSPD directly fabricated upon silicon without any cavity structure .