Mid-infrared(MIR)spectral imaging enables precise target identification and analysis by capturing rich chemical fingerprints,which calls for high-sensitivity broadband MIR imagers at room temperature.Here,we devise an...Mid-infrared(MIR)spectral imaging enables precise target identification and analysis by capturing rich chemical fingerprints,which calls for high-sensitivity broadband MIR imagers at room temperature.Here,we devise and implement a continuous-wave pumping MIR upconversion imaging system based on externalcavity enhancement,which favors a large field of view,a low cavity loss,and a high spectral resolution.The involved optical cavity is constructed in an integrated fashion by utilizing one crystal facet as a cavity mirror,which allows a 43-fold power enhancement for the single-longitudinal-mode pump at 1064 nm.In combination with the chirped-poling crystal design,high-fidelity and wide-field spectral imaging mapping is permitted to facilitate an acceptance angle of up to 28.5 deg over a spectral coverage of 2.5 to 5μm.Moreover,a thermal locking approach is used to stabilize the cavity at high-power operation,eliminating active feedback and ensuring long-term stability.A proof-of-principle demonstration is presented to showcase real-time observation of CO_(2)gas injection dynamics.The implemented MIR upconversion imager features wide-field operation,high detection sensitivity,and compact footprint,which would benefit subsequent applications,including environment monitoring,gas leakage inspection,and medical diagnostics.展开更多
Lanthanide-based upconversion core-shell NaGdF4 nanocrystals with strong upconversion luminescence and biocompatibility were synthesized by the solvothermal method.The multicolor upconversion emission of these NaGdF4 ...Lanthanide-based upconversion core-shell NaGdF4 nanocrystals with strong upconversion luminescence and biocompatibility were synthesized by the solvothermal method.The multicolor upconversion emission of these NaGdF4 nanoparticles could be easily obtained by controlling the core-shell compositions.These multicolor core-shell NaGdF4 upconversion nanocrystals could be employed as fluorescent probes for imaging the mouse hair,by which the porous and scalelike structure of the mouse hair were presented clearly.Meanwhile,it was directly shown by fluorescent signals that the mouse hair could resist the corrosion of the strong acid even when the concentration of hydrochloric acid was increased to 36.5%,but could not avoid the carbonization at high temperature of 400 oC.This procedure based on upconversion fluorescent nanoprobes opens a novel route for investigating the basic physical structure and chemical properties of biological tissue and organism.展开更多
We present an inexpensive technique to obtain a three-dimensional(3D) millimeter wave(MMW) and terahertz(THz) image using upconversion. In this work we describe and demonstrate a method for upconversion of MMW/THz rad...We present an inexpensive technique to obtain a three-dimensional(3D) millimeter wave(MMW) and terahertz(THz) image using upconversion. In this work we describe and demonstrate a method for upconversion of MMW/THz radiation to the visual band using a very inexpensive miniature glow discharge detector(GDD) and a silicon photodetector. We present MMW/THz upconversion images based on measuring the visual light emitting from the GDD rather than its electrical current. The results show better response time and better sensitivity compared to the electronic detection performed previously. Furthermore, in this work we perform frequency modulation continuous wave(FMCW) radar detection based on this method using a GDD lamp, with a photodetector to measure GDD light emission. By using FMCW detection, the range in addition to the intensity at each pixel can be obtained,thus yielding the 3D image. The GDD acts as a heterodyne mixer not only electronically but also optically. The suggested 3D upconversion technique using the GDD is simple and inexpensive and has better performance compared to other MMW/THz imaging systems suggested in the literature. This method provides minimum detectable signal power that is about 6 orders of magnitude better than similar plasma systems due to the very large internal signal gain deriving from the much smaller electrode separation and resulting in much higher plasma electric field.展开更多
基金supported by the Shanghai Pilot Program for Basic Research (Grant No. TQ20220104)the National Natural Science Foundation of China (Grant Nos. 62175064, 62235019, and 62035005)+4 种基金the Innovation Program for Quantum Science and Technology (Grant No. 2023ZD0301000)the Shanghai Municipal Science and Technology Major Project (Grant No. 2019SHZDZX01)the Natural Science Foundation of Chongqing (Grant Nos. CSTB2023NSCQ-JQX0011 and CSTB2022TIAD-DEX0036)the Fundamental Research Funds for the Central Universitiesthe China Postdoctoral Science Foundation (Grant No. 2024M760918)
文摘Mid-infrared(MIR)spectral imaging enables precise target identification and analysis by capturing rich chemical fingerprints,which calls for high-sensitivity broadband MIR imagers at room temperature.Here,we devise and implement a continuous-wave pumping MIR upconversion imaging system based on externalcavity enhancement,which favors a large field of view,a low cavity loss,and a high spectral resolution.The involved optical cavity is constructed in an integrated fashion by utilizing one crystal facet as a cavity mirror,which allows a 43-fold power enhancement for the single-longitudinal-mode pump at 1064 nm.In combination with the chirped-poling crystal design,high-fidelity and wide-field spectral imaging mapping is permitted to facilitate an acceptance angle of up to 28.5 deg over a spectral coverage of 2.5 to 5μm.Moreover,a thermal locking approach is used to stabilize the cavity at high-power operation,eliminating active feedback and ensuring long-term stability.A proof-of-principle demonstration is presented to showcase real-time observation of CO_(2)gas injection dynamics.The implemented MIR upconversion imager features wide-field operation,high detection sensitivity,and compact footprint,which would benefit subsequent applications,including environment monitoring,gas leakage inspection,and medical diagnostics.
基金Project supported by the National Natural Science Foundation of China(21301058,61274026)Innovation Foundation of Hunan University of Science and Technology(S140036)
文摘Lanthanide-based upconversion core-shell NaGdF4 nanocrystals with strong upconversion luminescence and biocompatibility were synthesized by the solvothermal method.The multicolor upconversion emission of these NaGdF4 nanoparticles could be easily obtained by controlling the core-shell compositions.These multicolor core-shell NaGdF4 upconversion nanocrystals could be employed as fluorescent probes for imaging the mouse hair,by which the porous and scalelike structure of the mouse hair were presented clearly.Meanwhile,it was directly shown by fluorescent signals that the mouse hair could resist the corrosion of the strong acid even when the concentration of hydrochloric acid was increased to 36.5%,but could not avoid the carbonization at high temperature of 400 oC.This procedure based on upconversion fluorescent nanoprobes opens a novel route for investigating the basic physical structure and chemical properties of biological tissue and organism.
基金North Atlantic Treaty Organization(NATO)Science for Peace and Security(SPS)Program(MD.SFPP984775)
文摘We present an inexpensive technique to obtain a three-dimensional(3D) millimeter wave(MMW) and terahertz(THz) image using upconversion. In this work we describe and demonstrate a method for upconversion of MMW/THz radiation to the visual band using a very inexpensive miniature glow discharge detector(GDD) and a silicon photodetector. We present MMW/THz upconversion images based on measuring the visual light emitting from the GDD rather than its electrical current. The results show better response time and better sensitivity compared to the electronic detection performed previously. Furthermore, in this work we perform frequency modulation continuous wave(FMCW) radar detection based on this method using a GDD lamp, with a photodetector to measure GDD light emission. By using FMCW detection, the range in addition to the intensity at each pixel can be obtained,thus yielding the 3D image. The GDD acts as a heterodyne mixer not only electronically but also optically. The suggested 3D upconversion technique using the GDD is simple and inexpensive and has better performance compared to other MMW/THz imaging systems suggested in the literature. This method provides minimum detectable signal power that is about 6 orders of magnitude better than similar plasma systems due to the very large internal signal gain deriving from the much smaller electrode separation and resulting in much higher plasma electric field.
