We present a scheme for estimating the noise-equivalent temperature difference(NETD)of frequency upconversion detectors(UCDs)that detect mid-infrared(MIR)light.In particular,we investigate the frequency upconversion o...We present a scheme for estimating the noise-equivalent temperature difference(NETD)of frequency upconversion detectors(UCDs)that detect mid-infrared(MIR)light.In particular,we investigate the frequency upconversion of a periodically poled crystal based on lithium niobate,where an MIR conversion bandwidth of 220 nm can be achieved in a single-poled period by a special design.Experimentally,for an MIR radiating target at a temperature of 95℃,the NETD of the device was estimated to be 56 mK with an exposure time of 1 s.Meanwhile,a direct measurement of the NETD was performed utilizing conventional methods,which resulted in 48 mK.We also compared the NETD of our UCD with commercially available direct MIR detectors.We show that the limiting factor for further NETD reduction of our device is not primarily from the upconversion process and camera noise but from the limitations of the heat source and laser performance.Our detectors have good temperature measurement performance and can be used for a variety of applications involving temperature object identification and material structure detection.展开更多
We present a method to generate a frequency-doubled microwave signal by employing a coupling-modulated ring resonator. Critical coupling is achieved when the resonator intrinsic loss is perfectly balanced by the exter...We present a method to generate a frequency-doubled microwave signal by employing a coupling-modulated ring resonator. Critical coupling is achieved when the resonator intrinsic loss is perfectly balanced by the external coupling enabled by a Mach–Zehnder interferometer coupler. The high suppression of the carrier leads to a clean two-tone optical signal with the frequency interval two times larger than that of the input microwave frequency.The beating of the two-tone signal at a photodiode generates the frequency upconverted microwave signal.A theoretical model is established to analyze the modulation process and the microwave signal generation.Experimental results show that the electrical harmonic suppression ratio is around ~20 dB(29 dB) for an input microwave signal with 5 dBm(10 dBm) power.展开更多
Optical frequency conversion based on the second-order nonlinearity(χ^((2))) only occurs in anisotropic media(or at interfaces) and thus is intrinsically polarization-dependent. But for practical applications, polari...Optical frequency conversion based on the second-order nonlinearity(χ^((2))) only occurs in anisotropic media(or at interfaces) and thus is intrinsically polarization-dependent. But for practical applications, polarization-insensitive or independent operation is highly sought after. Here, by leveraging polarization coupling and second-order nonlinearity, we experimentally demonstrate a paradigm of TE/TM polarization-independent frequency upconversion, i.e., sum frequency generation, in the periodically poled lithium niobate-on-insulator ridge waveguide. The cascading of quasi-phase-matched polarization coupling and nonlinear frequency conversion is exploited. With a proper transverse electric field, TE and TM mode fundamental waves can be frequency-upconverted with an equal efficiency in the frequency converter. The proposed method may find ready application in all-optical wavelength conversion and upconversion detection technologies.展开更多
A study is made of the effects of Doppler broadening on pure gain without inversion, which means that neither one-photon nor two-photon inversions are allowed, and non-pure gain without inversion, which means that one...A study is made of the effects of Doppler broadening on pure gain without inversion, which means that neither one-photon nor two-photon inversions are allowed, and non-pure gain without inversion, which means that one-photon inversion does not occur but two-photon inversion is present, in a closed A-type three-level system with incoherent pumping. It is shown that when the driving field is resonant but the probe field is not, in a certain range of Doppler width, for the case of the lower degree of frequency up-conversion, generally, pure gain without inversion increases monotonically and non-pure gain without inversion does not monotonically increase or decrease with increasing Doppler width; for the case of the higher degree of frequency up-conversion, pure gain without inversion decreases monotonically but non-pure gain without inversion cannot be produced. In the case of two-photon resonance, in some range of Doppler width, pure gain without inversion does not monotonically increase or decrease while non-pure gain without inversion decreases monotonically with Doppler width increasing. Finally, an experimental scheme for examining our theoretical result is given.展开更多
The two-photon absorption（TPA）and TPA-induced frequency upconversion emission properties of the dyes 4-[P-（dicyanoethylamino）crystal]-N-methypyrdinium iodide and the complex of 4-[P-（dicyanoethylamino）crystal]-N...The two-photon absorption（TPA）and TPA-induced frequency upconversion emission properties of the dyes 4-[P-（dicyanoethylamino）crystal]-N-methypyrdinium iodide and the complex of 4-[P-（dicyanoethylamino）crystal]-N-methypyrdinium iodide and Ce（NO3）3 were experimentally studied.It was found that the TPA cross section for the dye sensitized by Ce3＋ is two factors larger than that of the dye without being sensitized.A three-level system model of the dye molecules was used to analyze the enhancement of TPA by the sensitizer Ce3＋,which indicated that the sensitizer results in the increase of the transition dipole moment from the one-photon allowed excited state（1Bu）to the two-photon allowed excited state（2Ag）.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11934013 and 92065101)the Anhui Initiative In Quantum Information Technologies(Grant No.AHY020200)+1 种基金the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301100)the National Key Research and Development Program of China(Grant No.2022YFB3607700).
文摘We present a scheme for estimating the noise-equivalent temperature difference(NETD)of frequency upconversion detectors(UCDs)that detect mid-infrared(MIR)light.In particular,we investigate the frequency upconversion of a periodically poled crystal based on lithium niobate,where an MIR conversion bandwidth of 220 nm can be achieved in a single-poled period by a special design.Experimentally,for an MIR radiating target at a temperature of 95℃,the NETD of the device was estimated to be 56 mK with an exposure time of 1 s.Meanwhile,a direct measurement of the NETD was performed utilizing conventional methods,which resulted in 48 mK.We also compared the NETD of our UCD with commercially available direct MIR detectors.We show that the limiting factor for further NETD reduction of our device is not primarily from the upconversion process and camera noise but from the limitations of the heat source and laser performance.Our detectors have good temperature measurement performance and can be used for a variety of applications involving temperature object identification and material structure detection.
基金National Natural Science Foundation of China(NSFC)(61422508,61535006,61661130155)
文摘We present a method to generate a frequency-doubled microwave signal by employing a coupling-modulated ring resonator. Critical coupling is achieved when the resonator intrinsic loss is perfectly balanced by the external coupling enabled by a Mach–Zehnder interferometer coupler. The high suppression of the carrier leads to a clean two-tone optical signal with the frequency interval two times larger than that of the input microwave frequency.The beating of the two-tone signal at a photodiode generates the frequency upconverted microwave signal.A theoretical model is established to analyze the modulation process and the microwave signal generation.Experimental results show that the electrical harmonic suppression ratio is around ~20 dB(29 dB) for an input microwave signal with 5 dBm(10 dBm) power.
基金supported by the National Natural Science Foundation of China(Nos.12074252,12192252,62005159,62022058,61705127,and 12104289)the National Key Research and Development Program of China(No.2018YFA0306301)+2 种基金the Shanghai Municipal Science and Technology Major Project(No.2019SHZDZX01-ZX06)the Shanghai Rising-Star Program(No.20QA1405400)the Yangyang Development Fund.
文摘Optical frequency conversion based on the second-order nonlinearity(χ^((2))) only occurs in anisotropic media(or at interfaces) and thus is intrinsically polarization-dependent. But for practical applications, polarization-insensitive or independent operation is highly sought after. Here, by leveraging polarization coupling and second-order nonlinearity, we experimentally demonstrate a paradigm of TE/TM polarization-independent frequency upconversion, i.e., sum frequency generation, in the periodically poled lithium niobate-on-insulator ridge waveguide. The cascading of quasi-phase-matched polarization coupling and nonlinear frequency conversion is exploited. With a proper transverse electric field, TE and TM mode fundamental waves can be frequency-upconverted with an equal efficiency in the frequency converter. The proposed method may find ready application in all-optical wavelength conversion and upconversion detection technologies.
基金Project supported by the Natural Science Foundation of Shandong Province,China (Grant No Y2006A21)the National Natural Science Foundation of China (Grant No 10675076)
文摘A study is made of the effects of Doppler broadening on pure gain without inversion, which means that neither one-photon nor two-photon inversions are allowed, and non-pure gain without inversion, which means that one-photon inversion does not occur but two-photon inversion is present, in a closed A-type three-level system with incoherent pumping. It is shown that when the driving field is resonant but the probe field is not, in a certain range of Doppler width, for the case of the lower degree of frequency up-conversion, generally, pure gain without inversion increases monotonically and non-pure gain without inversion does not monotonically increase or decrease with increasing Doppler width; for the case of the higher degree of frequency up-conversion, pure gain without inversion decreases monotonically but non-pure gain without inversion cannot be produced. In the case of two-photon resonance, in some range of Doppler width, pure gain without inversion does not monotonically increase or decrease while non-pure gain without inversion decreases monotonically with Doppler width increasing. Finally, an experimental scheme for examining our theoretical result is given.
基金Supported by the National Natural Science Foundation of China(No.10074020).
文摘The two-photon absorption（TPA）and TPA-induced frequency upconversion emission properties of the dyes 4-[P-（dicyanoethylamino）crystal]-N-methypyrdinium iodide and the complex of 4-[P-（dicyanoethylamino）crystal]-N-methypyrdinium iodide and Ce（NO3）3 were experimentally studied.It was found that the TPA cross section for the dye sensitized by Ce3＋ is two factors larger than that of the dye without being sensitized.A three-level system model of the dye molecules was used to analyze the enhancement of TPA by the sensitizer Ce3＋,which indicated that the sensitizer results in the increase of the transition dipole moment from the one-photon allowed excited state（1Bu）to the two-photon allowed excited state（2Ag）.
