To date,most integrated quantum photonics experiments rely on single-photon detectors operating at cryogenic temperatures coupled to photonic integrated circuits(PICs)through single-mode optical fibers.This approach p...To date,most integrated quantum photonics experiments rely on single-photon detectors operating at cryogenic temperatures coupled to photonic integrated circuits(PICs)through single-mode optical fibers.This approach presents significant challenges due to the detection complexity,as cryogenic conditions hinder the development of scalable systems.In addition,going towards fully-integrated devices or,at least,removing the optical fibers would be also advantageous to develop compact and cost-efficient solutions featuring a high number of optical modes.This work reports on the direct coupling of a PIC,fabricated by femtosecond laser writing(FLW),and a silicon single-photon avalanche diode(SPAD)array,fabricated in a custom planar technology and compatible with the operation at room temperature.The effectiveness of this solution is shown by achieving perfect coupling and a system detection efficiency as high as 41.0%at a wavelength of 561 nm,which is the highest value reported to date among both heterogeneous/hybrid integrated and directly coupled systems.We also show the robustness of the coupling to misalignments,demonstrating that costly alignment procedures are not needed.Finally,we exploit the SPAD array to characterize a reconfigurable Mach-Zehnder interferometer,i.e.,the basic building block of multimode reconfigurable PICs.This solution provides a new avenue to the design and implementation of quantum photonics experiments,especially effective when compact and cost-efficient systems are needed.展开更多
文摘To date,most integrated quantum photonics experiments rely on single-photon detectors operating at cryogenic temperatures coupled to photonic integrated circuits(PICs)through single-mode optical fibers.This approach presents significant challenges due to the detection complexity,as cryogenic conditions hinder the development of scalable systems.In addition,going towards fully-integrated devices or,at least,removing the optical fibers would be also advantageous to develop compact and cost-efficient solutions featuring a high number of optical modes.This work reports on the direct coupling of a PIC,fabricated by femtosecond laser writing(FLW),and a silicon single-photon avalanche diode(SPAD)array,fabricated in a custom planar technology and compatible with the operation at room temperature.The effectiveness of this solution is shown by achieving perfect coupling and a system detection efficiency as high as 41.0%at a wavelength of 561 nm,which is the highest value reported to date among both heterogeneous/hybrid integrated and directly coupled systems.We also show the robustness of the coupling to misalignments,demonstrating that costly alignment procedures are not needed.Finally,we exploit the SPAD array to characterize a reconfigurable Mach-Zehnder interferometer,i.e.,the basic building block of multimode reconfigurable PICs.This solution provides a new avenue to the design and implementation of quantum photonics experiments,especially effective when compact and cost-efficient systems are needed.
