Spatial Light Manipulation Based On Micro/Nano Photonic Devices And Its Applications In Optical Communications

The spatial dimension of light is a kind of physical dimension that contains amplitude,phase,and polarization distruibutions of transverse space structure of light.Some kinds of light have caught increasing attention in various optical communication and noncommunication systems due to their features of spatial orthogonality and having angular momentum.To realize the utilizing of spatial dimension of light,it is necessary to perform effective spatial manipulation on light.However,traditional optical elements used to manipulate transverse optical structure suffer from large volume,long working distance,low accuracy,and rigorous working conditions.In addition,compared with traditional optical elements,micro/nano photonic devices such as metasurfaces and integrated devices with small size,short diffraction distance,and high accuracy are more attractive.Therefore,to solve the key problems existing in spatial light manipulation technology and realize various applications,researches on spatial light manipulation using micro/nano photonic devices and spatial light manipulation applied in optical communication systems are studied both theoretically and experimentally.The major contents of this dissertation are summarized as follows:(1)Spatial light manipulation based on metasurfaces.(1)The amplitude and phase responses of metal V-shaped antenna in optical region are theoretical studied.A kind of metasurface based on V-shaped antenna to perfom multicasting from a single Gaussian beam to four twisted lights is designed and simulated.The simulated results indicates that the designed metasurface can successfully generate 4-fold twisted light multicasting and crosstalk of multicasting is less than-15 dB.(2)A kind of metal metasurface is designed and fabricated on the facet of fiber to generate higher-order linearly polarized(LP)mode.The experiment on the fabricated metasurface is investigated and the results show that the metasurface can successfully generate LP11 mode in the fiber.(3)A nanophotonic alldielectric metasurface based on silicon-on-insulator is designed,fabricated and demonstrated to manipulate twisted light.The proposed metasurface can realize full-phase control and flexible amplitude adjustment of wavefront.Experimental results indicate that twisted lights can be successfully generated and detected using the fabricated metasurfaces.Then twisted lights manipulation applied in optical communication using presented metasurface is investigated.The results show that multiplexing/demultiplexing of twisted lights using fabricated metasurfaces is feasible and binary images carried in the twisted lights can be transmitted to receiver without distortion.(4)A nanophotonic all-dielectric metasurface based on silicon-on-insulator is designed to realize Bessel beams generation and 6-fold twisted lights multicasting.The generated Bessel beams have high purity and the crosstalks between the multicasted twisted lights and their neighboring ones are less than-14 dB.(2)Spatial light manipulation based on integrated devices.Manipulation on traditional dimensions of light using integrated devices is studied.An air slot hybrid surface plasmon polarities(SPP)waveguide is designed and fabricated to be applied in high-speed data transmission.The experimental results show that the fabricated waveguide can realize terabit/s data transmission.A compact on-chip twisted light array emitter on the basis of siliconon-insulator platform is proposed on the theory of three-plane-wave interference and realized using a kind of specially designed tilt gratings.The simulation results indicate that the designed emitter can effectively generate a network of twisted light.Then the proposed twisted light array emitter is fabricated and experimentally demonstrated,which confirms the simulated prediction and exhibits the favorable performance.(3)Spatial light manipulation applied in optical communication systems.(1)A 12-mdistance coding/decoding using Bessel beams in free-space is experimentally demonstrated.An opaque obstruction is placed at transverse positions along the propagation path of light to evaluate its impacts on coding/decoding process.The bit error rate(BER)of hexadecimal coding/decoding based on Bessel beams with small topological number space is zero,while the 32-ary coding/decoding based on Bessel beams with large topological number space has terrible BER performance.The results indicate that Bessel beams can be used to realize obstruction-free m-ary coding/decoding optical communication system.(2)Analog links in a 5-km few mode fiber(FMF)are experimentally investigated by exploiting spatial modes of LP01,LP11a(b),and OAM±1(OAM: orbital angular momentum).Spurious free dynamic range of the second-order harmonic distortion is used to evaluate the analog link performance.The obtained results indicate that the analog link performance through FMF is affected by mode relative loss under the condition of the same input optical power.While under the conditional of the same mode relative loss,all modes have simuliar analog link performance.