Frequency up-conversion is an effective method of mid-infrared(MIR) detection by converting long-wavelength photons to the visible domain, where efficient detectors are readily available. Here, we generate MIR light c...Frequency up-conversion is an effective method of mid-infrared(MIR) detection by converting long-wavelength photons to the visible domain, where efficient detectors are readily available. Here, we generate MIR light carrying orbital angular momentum(OAM) from a difference frequency generation process and perform up-conversion on it via sum frequency conversion in a bulk quasi-phase-matching crystal. The maximum quantum conversion efficiencies from MIR to visible are 34.0%, 10.4%, and 3.5% for light with topological charges of 0, 1, and 2, respectively, achieved by utilizing an optimized strong pump light. We also verify the OAM conservation with a specially designed interferometer, and the results agree well with the numerical simulations. Our study opens up the possibilities for generating, manipulating, and detecting MIR light that carries OAM, and will have great potential for optical communications and remote sensing in the MIR regime.展开更多
Optical interference is not only a fundamental phenomenon that has enabled new theories of light to be derived but it has also been used in interferometry for the measurement of small displacements,refractive index ch...Optical interference is not only a fundamental phenomenon that has enabled new theories of light to be derived but it has also been used in interferometry for the measurement of small displacements,refractive index changes,and surface irregularities.In a two-beam interferometer,variations in the interference fringes are used as a diagnostic for anything that causes the optical path difference(OPD)to change;therefore,for a specified OPD,greater variation in the fringes indicates better measurement sensitivity.Here,we introduce and experimentally validate an interesting optical interference phenomenon that uses photons with a structured frequency-angular spectrum,which are generated from a spontaneous parametric down-conversion process in a nonlinear crystal.This interference phenomenon is manifested as interference fringes that vary much more rapidly with increasing OPD than the corresponding fringes for equal-inclination interference;the phenomenon is parameterised using an equivalent wavelength,which under our experimental conditions is 29.38 nm or about 1/27 of the real wavelength.This phenomenon not only enriches the knowledge with regard to optical interference but also offers promise for applications in interferometry.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 92065101 and 11934013)Anhui Initiative In Quantum Information Technologies (Grant No. AHY020200)。
文摘Frequency up-conversion is an effective method of mid-infrared(MIR) detection by converting long-wavelength photons to the visible domain, where efficient detectors are readily available. Here, we generate MIR light carrying orbital angular momentum(OAM) from a difference frequency generation process and perform up-conversion on it via sum frequency conversion in a bulk quasi-phase-matching crystal. The maximum quantum conversion efficiencies from MIR to visible are 34.0%, 10.4%, and 3.5% for light with topological charges of 0, 1, and 2, respectively, achieved by utilizing an optimized strong pump light. We also verify the OAM conservation with a specially designed interferometer, and the results agree well with the numerical simulations. Our study opens up the possibilities for generating, manipulating, and detecting MIR light that carries OAM, and will have great potential for optical communications and remote sensing in the MIR regime.
基金This work was supported by the National Natural Science Foundation of China(NSFC)(61605194,11934013,61525504)the Anhui Initiative In Quantum Information Technologies(AHY020200)the China Postdoctoral Science Foundation(2017M622003,2018M642517).
文摘Optical interference is not only a fundamental phenomenon that has enabled new theories of light to be derived but it has also been used in interferometry for the measurement of small displacements,refractive index changes,and surface irregularities.In a two-beam interferometer,variations in the interference fringes are used as a diagnostic for anything that causes the optical path difference(OPD)to change;therefore,for a specified OPD,greater variation in the fringes indicates better measurement sensitivity.Here,we introduce and experimentally validate an interesting optical interference phenomenon that uses photons with a structured frequency-angular spectrum,which are generated from a spontaneous parametric down-conversion process in a nonlinear crystal.This interference phenomenon is manifested as interference fringes that vary much more rapidly with increasing OPD than the corresponding fringes for equal-inclination interference;the phenomenon is parameterised using an equivalent wavelength,which under our experimental conditions is 29.38 nm or about 1/27 of the real wavelength.This phenomenon not only enriches the knowledge with regard to optical interference but also offers promise for applications in interferometry.
