Reliable generation of single photons is of key importance for fundamental physical experiments and quantum protocols.The periodically poled lithium niobate[LN]waveguide has shown promise for an integrated quantum sou...Reliable generation of single photons is of key importance for fundamental physical experiments and quantum protocols.The periodically poled lithium niobate[LN]waveguide has shown promise for an integrated quantum source due to its large spectral tunability and high efficiency,benefiting from the quasi-phase-matching.Here we demonstrate photon-pair sources based on an LN waveguide periodically poled by a tightly focused femtosecond laser beam.The pair coincidence rate reaches~8000 counts per second for average pump power of 3.2 m W[peak power is 2.9 k W).Our results prove the possibility of application of the nonlinear photonics structure fabricated by femtosecond laser to the integrated quantum source.This method can be extended to three-dimensional domain structures,which provide a potential platform for steering the spatial degree of freedom of the entangled two-photon states.展开更多
Ultrabroadband laser sources are highly desirable in a wide variety of modern science disciplines ranging from physics,chemistry and materials science to information communications and processing.Here we present the d...Ultrabroadband laser sources are highly desirable in a wide variety of modern science disciplines ranging from physics,chemistry and materials science to information communications and processing.Here we present the design and fabrication of a chirped periodically poled lithium niobate(CPPLN)nonlinear photonic crystal that supports multiple orders of quasiphase matching with finite bandwidth and allows for the simultaneous broadband generation of second and third harmonics with high conversion efficiency.Moreover,the chirp rate has a significant influence on the conversion efficiency and bandwidth.The CPPLN scheme offers a promising approach for the construction of short-wavelength laser sources and enables the generation of the three primary colors—red,green and blue—from a single crystal,which may have potential applications in large-screen laser displays.展开更多
The nonlinear Talbot effect is a near-field nonlinear diffraction phenomenon in which the self-imaging of periodic objects is formed by the second harmonics of the incident laser beam. We demonstrate the first, to the...The nonlinear Talbot effect is a near-field nonlinear diffraction phenomenon in which the self-imaging of periodic objects is formed by the second harmonics of the incident laser beam. We demonstrate the first, to the best of our knowledge, example of nonlinear Talbot self-healing, i.e., the capability of creating defect-free images from faulty nonlinear optical structures. In particular, we employ the tightly focused femtosecond infrared optical pulses to fabricate LiNbO_(3) nonlinear photonic crystals and show that the defects in the form of the missing points of two-dimensional square and hexagonal periodic structures are restored in the second harmonic images at the first nonlinear Talbot plane. The observed nonlinear Talbot self-healing opens up new possibilities for defect-tolerant optical lithography and printing.展开更多
基金supported financially by the National Key R&D Program of China(Nos.2019YFA0705000,2017YFA0303800,2017YFA0303700,2019YFA0308700,and 2020YFA0309500)the National Natural Science Foundation of China(Nos.12074197,12074196,11774183,and 11922406)。
文摘Reliable generation of single photons is of key importance for fundamental physical experiments and quantum protocols.The periodically poled lithium niobate[LN]waveguide has shown promise for an integrated quantum source due to its large spectral tunability and high efficiency,benefiting from the quasi-phase-matching.Here we demonstrate photon-pair sources based on an LN waveguide periodically poled by a tightly focused femtosecond laser beam.The pair coincidence rate reaches~8000 counts per second for average pump power of 3.2 m W[peak power is 2.9 k W).Our results prove the possibility of application of the nonlinear photonics structure fabricated by femtosecond laser to the integrated quantum source.This method can be extended to three-dimensional domain structures,which provide a potential platform for steering the spatial degree of freedom of the entangled two-photon states.
基金This work was supported by the 973 Program of China(No.2011CB922002 and No.2013CB632704)the Knowledge Innovation Program of the Chinese Academy of Sciences(No.Y1 V2013 L11).
文摘Ultrabroadband laser sources are highly desirable in a wide variety of modern science disciplines ranging from physics,chemistry and materials science to information communications and processing.Here we present the design and fabrication of a chirped periodically poled lithium niobate(CPPLN)nonlinear photonic crystal that supports multiple orders of quasiphase matching with finite bandwidth and allows for the simultaneous broadband generation of second and third harmonics with high conversion efficiency.Moreover,the chirp rate has a significant influence on the conversion efficiency and bandwidth.The CPPLN scheme offers a promising approach for the construction of short-wavelength laser sources and enables the generation of the three primary colors—red,green and blue—from a single crystal,which may have potential applications in large-screen laser displays.
基金supported by the National Natural Science Foundation of China(Nos.61905124,11974196,and 61905125)the Australian Research Council(No.DP19010774)+2 种基金the Qatar National Research Fund(No.NPRP 12S-0205190047)the Yongjiang Scholar Foundation of Ningbothe K.C.Wong Magna Fund of Ningbo University。
文摘The nonlinear Talbot effect is a near-field nonlinear diffraction phenomenon in which the self-imaging of periodic objects is formed by the second harmonics of the incident laser beam. We demonstrate the first, to the best of our knowledge, example of nonlinear Talbot self-healing, i.e., the capability of creating defect-free images from faulty nonlinear optical structures. In particular, we employ the tightly focused femtosecond infrared optical pulses to fabricate LiNbO_(3) nonlinear photonic crystals and show that the defects in the form of the missing points of two-dimensional square and hexagonal periodic structures are restored in the second harmonic images at the first nonlinear Talbot plane. The observed nonlinear Talbot self-healing opens up new possibilities for defect-tolerant optical lithography and printing.
