Diffractive lenses(DLs)can realize high-resolution imaging with light weight and compact size.Conventional DLs suffer large chromatic and off-axis aberrations,which significantly limits their practical applications.Al...Diffractive lenses(DLs)can realize high-resolution imaging with light weight and compact size.Conventional DLs suffer large chromatic and off-axis aberrations,which significantly limits their practical applications.Although many achromatic methods have been proposed,most of them are used for designing small aperture DLs,which have low diffraction efficiencies.In the designing of diffractive achromatic lenses,increasing the aperture and improving the diffraction efficiency have become two of the most important design issues.Here,a novel phase-coded diffractive lens(PCDL)for achromatic imaging with a large aperture and high efficiency is proposed and demonstrated experimentally,and it also possesses wide field-of-view(FOV)imaging at the same time.The phase distribution of the conventional phase-type diffractive lens(DL)is coded with a cubic function to expand both the working bandwidth and the FOV of conventional DL.The proposed phase-type DL is fabricated by using the laser direct writing of grey-scale patterns for a PCDL of a diameter of 10 mm,a focal length of 100 mm,and a cubic phase coding parameter of 30π.Experimental results show that the working bandwidth and the FOV of the PCDL respectively reach 50 nm and 16°with over 8%focusing efficiency,which are in significant contrast to the counterparts of conventional DL and in good agreement with the theoretical predictions.This work provides a novel way for implementing the achromatic,wide FOV,and high-efficiency imaging with large aperture DL.展开更多
High-speed optical interconnects of data centers and high performance computers(HPC) have become the rapid development direction in the field of opticalcommunication owing to the explosive growth of market demand. Cur...High-speed optical interconnects of data centers and high performance computers(HPC) have become the rapid development direction in the field of opticalcommunication owing to the explosive growth of market demand. Currently, opticalinterconnect systems are moving towards higher capacity and integration.High-sensitivity receivers with avalanche photodiodes (APDs) are paid more attentiondue to the capability to enhance gain bandwidth. The impact ionization coefficientratio is one crucial parameter for avalanche photodiode optimization, whichsignificantly affects the excess noise and the gain bandwidth product (GBP). Thedevelopment of silicon-germanium (Si-Ge) APDs are promising thanks to the lowimpact ionization coefficient ratio of silicon, the simple structure, and the CMOScompatible process. Separate absorption charge multiplication (SACM) structures aretypically adopted in Si-Ge APDs to achieve high bandwidth and low noise. This paperreviews design and optimization in high-speed Si-Ge APDs, including advanced APDstructures, APD modeling and APD receivers.展开更多
Full-color imaging is of critical importance in digital pathology for analyzing labeled tissue sections.In our previous cover story[Sci.China:Phys.,Mech.Astron.64,114211(2021)],a color transfer approach was implemente...Full-color imaging is of critical importance in digital pathology for analyzing labeled tissue sections.In our previous cover story[Sci.China:Phys.,Mech.Astron.64,114211(2021)],a color transfer approach was implemented on Fourier ptychographic microscopy(FPM)for achieving high-throughput full-color whole slide imaging without mechanical scanning.The approach was able to reduce both acquisition and reconstruction time of FPM by three-fold with negligible trade-off on color accuracy.However,the method cannot properly stain samples with two or more dyes due to the lack of spatial constraints in the color transfer process.It also requires a high computation cost in histogram matching of individual patches.Here we report a modified full-color imaging algorithm for FPM,termed color-transfer filtering FPM(CFFPM).In CFFPM,we replace the original histogram matching process with a combination of block processing and trilateral spatial filtering.The former step reduces the search of the solution space for colorization,and the latter introduces spatial constraints that match the low-resolution measurement.We further adopt an iterative process to refine the results.We show that this method can perform accurate and fast color transfer for various specimens,including those with multiple stains.The statistical results of 26 samples show that the average root mean square error is only 1.26%higher than that of the red-green-blue sequential acquisition method.For some cases,CFFPM outperforms the sequential method because of the coherent artifacts introduced by dust particles.The reported CFFPM strategy provides a turnkey solution for digital pathology via computational optical imaging.展开更多
Although the effective“stealth”of space vehicles is important,current camouflage designs are inadequate in meeting all application requirements.Here,a multilayer wavelength-selective emitter is demonstrated.It can r...Although the effective“stealth”of space vehicles is important,current camouflage designs are inadequate in meeting all application requirements.Here,a multilayer wavelength-selective emitter is demonstrated.It can realize visible light and dual-band mid-infrared camouflage with thermal control management in two application scenarios,with better effect and stronger radiation cooling capability,which can significantly improve the stealth and survivability of space vehicles in different environments.The selective emitter demonstrated in this paper has the advantages of simple structure,scalability,and ease of large-area fabrication,and has made a major breakthrough in driving multiband stealth technology from simulation research to physical verification and even practical application.展开更多
基金the National Natural Science Foundation of China(Grant No.61775154)the Natural Science Foundation of the Jiangsu Higher Education Institutions,China(Grant No.18KJB140015)+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions,Chinathe Open Research Fund of CAS Key Laboratory of Space Precision Measurement Technology,China(Grant No.SPMT2021001)。
文摘Diffractive lenses(DLs)can realize high-resolution imaging with light weight and compact size.Conventional DLs suffer large chromatic and off-axis aberrations,which significantly limits their practical applications.Although many achromatic methods have been proposed,most of them are used for designing small aperture DLs,which have low diffraction efficiencies.In the designing of diffractive achromatic lenses,increasing the aperture and improving the diffraction efficiency have become two of the most important design issues.Here,a novel phase-coded diffractive lens(PCDL)for achromatic imaging with a large aperture and high efficiency is proposed and demonstrated experimentally,and it also possesses wide field-of-view(FOV)imaging at the same time.The phase distribution of the conventional phase-type diffractive lens(DL)is coded with a cubic function to expand both the working bandwidth and the FOV of conventional DL.The proposed phase-type DL is fabricated by using the laser direct writing of grey-scale patterns for a PCDL of a diameter of 10 mm,a focal length of 100 mm,and a cubic phase coding parameter of 30π.Experimental results show that the working bandwidth and the FOV of the PCDL respectively reach 50 nm and 16°with over 8%focusing efficiency,which are in significant contrast to the counterparts of conventional DL and in good agreement with the theoretical predictions.This work provides a novel way for implementing the achromatic,wide FOV,and high-efficiency imaging with large aperture DL.
基金supported by Shaanxi Province Overseas High-Level Talents Program,Chinese Academy of Sciences 100 Talents Program,Xi’an Institute of Optics and Precision Mechanics Start-Up Funding,and State Key Laboratory of Transient Optics and Photonics Independent Research Project.
文摘High-speed optical interconnects of data centers and high performance computers(HPC) have become the rapid development direction in the field of opticalcommunication owing to the explosive growth of market demand. Currently, opticalinterconnect systems are moving towards higher capacity and integration.High-sensitivity receivers with avalanche photodiodes (APDs) are paid more attentiondue to the capability to enhance gain bandwidth. The impact ionization coefficientratio is one crucial parameter for avalanche photodiode optimization, whichsignificantly affects the excess noise and the gain bandwidth product (GBP). Thedevelopment of silicon-germanium (Si-Ge) APDs are promising thanks to the lowimpact ionization coefficient ratio of silicon, the simple structure, and the CMOScompatible process. Separate absorption charge multiplication (SACM) structures aretypically adopted in Si-Ge APDs to achieve high bandwidth and low noise. This paperreviews design and optimization in high-speed Si-Ge APDs, including advanced APDstructures, APD modeling and APD receivers.
基金National Natural Science Foundation of China (12104500).
文摘Full-color imaging is of critical importance in digital pathology for analyzing labeled tissue sections.In our previous cover story[Sci.China:Phys.,Mech.Astron.64,114211(2021)],a color transfer approach was implemented on Fourier ptychographic microscopy(FPM)for achieving high-throughput full-color whole slide imaging without mechanical scanning.The approach was able to reduce both acquisition and reconstruction time of FPM by three-fold with negligible trade-off on color accuracy.However,the method cannot properly stain samples with two or more dyes due to the lack of spatial constraints in the color transfer process.It also requires a high computation cost in histogram matching of individual patches.Here we report a modified full-color imaging algorithm for FPM,termed color-transfer filtering FPM(CFFPM).In CFFPM,we replace the original histogram matching process with a combination of block processing and trilateral spatial filtering.The former step reduces the search of the solution space for colorization,and the latter introduces spatial constraints that match the low-resolution measurement.We further adopt an iterative process to refine the results.We show that this method can perform accurate and fast color transfer for various specimens,including those with multiple stains.The statistical results of 26 samples show that the average root mean square error is only 1.26%higher than that of the red-green-blue sequential acquisition method.For some cases,CFFPM outperforms the sequential method because of the coherent artifacts introduced by dust particles.The reported CFFPM strategy provides a turnkey solution for digital pathology via computational optical imaging.
基金National Key Research and Development Program of China(2021YFC2202103,2021YFC2202203)National Natural Science Foundation of China(12103081,42101380,61875257)。
文摘Although the effective“stealth”of space vehicles is important,current camouflage designs are inadequate in meeting all application requirements.Here,a multilayer wavelength-selective emitter is demonstrated.It can realize visible light and dual-band mid-infrared camouflage with thermal control management in two application scenarios,with better effect and stronger radiation cooling capability,which can significantly improve the stealth and survivability of space vehicles in different environments.The selective emitter demonstrated in this paper has the advantages of simple structure,scalability,and ease of large-area fabrication,and has made a major breakthrough in driving multiband stealth technology from simulation research to physical verification and even practical application.
