To achieve photon-pair generation scaling, we optimize the quality factor of microring resonators for efficient continuous-wave-pumped spontaneous four-wave mixing. Numerical studies indicate that a high intrinsic qua...To achieve photon-pair generation scaling, we optimize the quality factor of microring resonators for efficient continuous-wave-pumped spontaneous four-wave mixing. Numerical studies indicate that a high intrinsic quality factor makes high pair rate and pair brightness possible, in which the maximums take place under overcoupling and critical-coupling conditions, respectively. We fabricate six all-pass-type microring resonator samples on a silicon-on-insulator chip involving gap width as the only degree of freedom. The signal count rate, pair brightness,and coincidence rate of all the samples are characterized, which are then compared with the modified simulations by taking the detector saturation and nonlinear loss into account. Being experimentally validated for the first time to the best of our knowledge, this work explicitly demonstrates that reducing the round-trip loss in a ring cavity and designing the corresponding optimized gap width are more effective to generate high-rate or high-brightness photon pairs than the conventional strategy of simply increasing the quality factor.展开更多
Optical scanning holography(OSH)records both the amplitude and phase information of a 3D object by a 2D scan.To reconstruct a 3D volumetric image from an OSH hologram is difficult,as it suffers from the defocus noise ...Optical scanning holography(OSH)records both the amplitude and phase information of a 3D object by a 2D scan.To reconstruct a 3D volumetric image from an OSH hologram is difficult,as it suffers from the defocus noise from the other sections.The use of a random phase pupil can convert defocus noise into speckle-like noise,which may require further processing in sectional image reconstruction.In this paper,we propose a U-shaped neural network to reduce this speckle haze.Simulation results show that the proposed method works effectively and efficiently both in simple and complex graphics.展开更多
The optical scanning holography(OSH)technique can capture all the three-dimensional volume information of an object in a hologram via a single raster scan.The digital hologram can then be processed to reconstruct indi...The optical scanning holography(OSH)technique can capture all the three-dimensional volume information of an object in a hologram via a single raster scan.The digital hologram can then be processed to reconstruct individual sectional images of the object.In this paper,we present a scheme to reconstruct sectional images in OSH with enhanced depth resolution,where a spatial light modulator(SLM)is adopted as a configurable point pupil.By switching the SLM between two states,different Fresnel zone plates(FZPs)are generated based on the same optical system.With extra information provided by different FZPs,a depth resolution at 0.7μm can be achieved.展开更多
In optical scanning holography, one pupil produces a spherical wave and another produces a plane wave. They interfere with each other and result in a fringe pattern for scanning a three-dimensional object. The resolut...In optical scanning holography, one pupil produces a spherical wave and another produces a plane wave. They interfere with each other and result in a fringe pattern for scanning a three-dimensional object. The resolution of the hologram reconstruction is affected by the point spread function(PSF) of the optical system. In this paper, we modulate the PSF by a spiral phase plate, which significantly enhances the lateral and depth resolution. We explain the theory for such resolution enhancement and show simulation results to verify the efficacy of the approach.展开更多
基金National Natural Science Foundation of China(NSFC)(60907003)Natural Science Foundation of Hunan Province,China(13JJ3001)+2 种基金Program for New Century Excellent Talents in University(NCET),China(NCET-12-0142)Danmarks Grundforskningsfond(DNRF)(DNRF123)China Scholarship Council(CSC)
文摘To achieve photon-pair generation scaling, we optimize the quality factor of microring resonators for efficient continuous-wave-pumped spontaneous four-wave mixing. Numerical studies indicate that a high intrinsic quality factor makes high pair rate and pair brightness possible, in which the maximums take place under overcoupling and critical-coupling conditions, respectively. We fabricate six all-pass-type microring resonator samples on a silicon-on-insulator chip involving gap width as the only degree of freedom. The signal count rate, pair brightness,and coincidence rate of all the samples are characterized, which are then compared with the modified simulations by taking the detector saturation and nonlinear loss into account. Being experimentally validated for the first time to the best of our knowledge, this work explicitly demonstrates that reducing the round-trip loss in a ring cavity and designing the corresponding optimized gap width are more effective to generate high-rate or high-brightness photon pairs than the conventional strategy of simply increasing the quality factor.
文摘Optical scanning holography(OSH)records both the amplitude and phase information of a 3D object by a 2D scan.To reconstruct a 3D volumetric image from an OSH hologram is difficult,as it suffers from the defocus noise from the other sections.The use of a random phase pupil can convert defocus noise into speckle-like noise,which may require further processing in sectional image reconstruction.In this paper,we propose a U-shaped neural network to reduce this speckle haze.Simulation results show that the proposed method works effectively and efficiently both in simple and complex graphics.
基金This research was supported in part by the Research Grants Council of the Hong Kong Special Administrative Region,China,under Projects HKU 7138/11E and 7131/12EH.Ou is also grateful to the National Science Foundation of China(Grant 61107018)the Fundamental Research Funds for the Central Universities(ZYGX2011J033),which allow her to enter into this collaborative research.
文摘The optical scanning holography(OSH)technique can capture all the three-dimensional volume information of an object in a hologram via a single raster scan.The digital hologram can then be processed to reconstruct individual sectional images of the object.In this paper,we present a scheme to reconstruct sectional images in OSH with enhanced depth resolution,where a spatial light modulator(SLM)is adopted as a configurable point pupil.By switching the SLM between two states,different Fresnel zone plates(FZPs)are generated based on the same optical system.With extra information provided by different FZPs,a depth resolution at 0.7μm can be achieved.
基金supported in part by the Research Grants Council of the Hong Kong Special Administrative Region,China, under project 7131–12Ethe NSFC RGC grant under project N–HKU714–13
文摘In optical scanning holography, one pupil produces a spherical wave and another produces a plane wave. They interfere with each other and result in a fringe pattern for scanning a three-dimensional object. The resolution of the hologram reconstruction is affected by the point spread function(PSF) of the optical system. In this paper, we modulate the PSF by a spiral phase plate, which significantly enhances the lateral and depth resolution. We explain the theory for such resolution enhancement and show simulation results to verify the efficacy of the approach.
