.Unidirectional imagers form images of input objects only in one direction,e.g.,from field-of-view(FOV)A to FOV B,while blocking the image formation in the reverse direction,from FOV B to FOV A.Here,we report unidirec....Unidirectional imagers form images of input objects only in one direction,e.g.,from field-of-view(FOV)A to FOV B,while blocking the image formation in the reverse direction,from FOV B to FOV A.Here,we report unidirectional imaging under spatially partially coherent light and demonstrate high-quality imaging only in the forward direction(A→B)with high power efficiency while distorting the image formation in the backward direction(B→A)along with low power efficiency.Our reciprocal design features a set of spatially engineered linear diffractive layers that are statistically optimized for partially coherent illumination with a given phase correlation length.Our analyses reveal that when illuminated by a partially coherent beam with a correlation length of≥∼1.5λ,whereλis the wavelength of light,diffractive unidirectional imagers achieve robust performance,exhibiting asymmetric imaging performance between the forward and backward directions—as desired.A partially coherent unidirectional imager designed with a smaller correlation length of<1.5λstill supports unidirectional image transmission but with a reduced figure of merit.These partially coherent diffractive unidirectional imagers are compact(axially spanning<75λ),polarization-independent,and compatible with various types of illumination sources,making them well-suited for applications in asymmetric visual information processing and communication.展开更多
Orbital angular momentum(OAM)-carrying beams have received extensive attention due to their high-dimensional characteristics in the context of free-space optical communication.However,accurate OAM mode recognition sti...Orbital angular momentum(OAM)-carrying beams have received extensive attention due to their high-dimensional characteristics in the context of free-space optical communication.However,accurate OAM mode recognition still suffers from reference misalignment of lateral displacement,beam waist size,and initial phase.Here we propose a deep-learning method to exquisitely recognize OAM modes under misalignment by using an alignment-free fractal multipoint interferometer.Our experiments achieve 98.35% recognizing accuracy when strong misalignment is added to hyperfine OAM modes whose Bures distance is 0.01.The maximum lateral displacement we added with respect to the perfectly on-axis beam is about±0.5 beam waist size.This work offers a superstable proposal for OAM mode recognition in the application of free-space optical communication and allows an increase of the communication capacity.展开更多
文摘.Unidirectional imagers form images of input objects only in one direction,e.g.,from field-of-view(FOV)A to FOV B,while blocking the image formation in the reverse direction,from FOV B to FOV A.Here,we report unidirectional imaging under spatially partially coherent light and demonstrate high-quality imaging only in the forward direction(A→B)with high power efficiency while distorting the image formation in the backward direction(B→A)along with low power efficiency.Our reciprocal design features a set of spatially engineered linear diffractive layers that are statistically optimized for partially coherent illumination with a given phase correlation length.Our analyses reveal that when illuminated by a partially coherent beam with a correlation length of≥∼1.5λ,whereλis the wavelength of light,diffractive unidirectional imagers achieve robust performance,exhibiting asymmetric imaging performance between the forward and backward directions—as desired.A partially coherent unidirectional imager designed with a smaller correlation length of<1.5λstill supports unidirectional image transmission but with a reduced figure of merit.These partially coherent diffractive unidirectional imagers are compact(axially spanning<75λ),polarization-independent,and compatible with various types of illumination sources,making them well-suited for applications in asymmetric visual information processing and communication.
基金National Natural Science Foundation of China(11534008,91736104)Ministry of Science and Technology of the People's Republic of China(2016YFA0301404)Fundamental Research Funds for the Central Universities.
文摘Orbital angular momentum(OAM)-carrying beams have received extensive attention due to their high-dimensional characteristics in the context of free-space optical communication.However,accurate OAM mode recognition still suffers from reference misalignment of lateral displacement,beam waist size,and initial phase.Here we propose a deep-learning method to exquisitely recognize OAM modes under misalignment by using an alignment-free fractal multipoint interferometer.Our experiments achieve 98.35% recognizing accuracy when strong misalignment is added to hyperfine OAM modes whose Bures distance is 0.01.The maximum lateral displacement we added with respect to the perfectly on-axis beam is about±0.5 beam waist size.This work offers a superstable proposal for OAM mode recognition in the application of free-space optical communication and allows an increase of the communication capacity.
