Research On Optical Microstructure Enabled Airy Beam Generation And On-Chip Mode Manipulation

In recent years,powered by advanced technology of micro/nano fabrication,increasing attention has been paid to optical microstructures,such as metasurface and micro-nano waveguide,for their extreme capacities to manipulate lights in subwavelength scale.Various types of optical microstructures enabled novel optical elements may change the amplitude,phase,polarizations and other physical dimensions for the high-efficiency manipulation for the spatial light field.And all types of photonic integrated devices can be used to realize the on-chip transmission,interconnection,and processing of optical information by introducing optical microstructures to control the order and polarization for the modal properties of guided waves.However,many optical devices based on microstructures still do not explore the potential of manipulating light,hence the functions and performances of those devices are still not perfect.This thesis focuses on two application scenarios,Airy beam generation and on-chip mode manipulation,to realize efficient and multi-dimensional manipulation of light with utilizing optical microstructures.The major research contents are summarized as follows:?.Metasurface enabled Airy beam generating methods are studied.A kind of Huygens'metasurfaces is proposed,to realize the efficient generation of Airy beam with both amplitude and phase modulation:this thesis designs a series of Huygens'metasurface units which can support electric and magnetic dipole responses simultaneously,and then uses these Huygens'metasurface units to construct Airy beam generators.The designed devices are fabricated and experimentally verified.A scheme of compact broadband on-chip Airy beam emitter is proposed:based on holographic technology,a shallow-etched metasurface enabled guided wave–driven Airy beam emitter is designed.Numerical simulations show that this device can convert guided waves into spatial Airy beams within the wavelength range of 1480?1580 nm.?.On-chip mode manipulation with plasmonic metasurfaces are studied.A plasmonic metasurfaces enabled ultra-compact broadband silicon waveguide transverse-magnetic pass polarizer is proposed:with loading metasurface composed of gradient-length gold nanorods on the silicon waveguide,transverse-electric mode in the silicon waveguide can couple into the surface wave mode supported by the metasurface,then be absorbed,while the transverse-magnetic mode is hardly influenced.The co-designed waveguide polarizer has the extinction ratio of 27.7 d B at 1550 nm wavelength with the footprint of 2.4×0.34?m~2.The concept of meta-coupler array is proposed,for coupling spatial light into the aimed supermodes in dual-waveguide or multiple-waveguide systems:meta-coupler arrays for routing polarization in dual-waveguide systems,and generating topological edge and interface modes in multiple-waveguide systems are designed and verified with simulations.?.Mode-hybridization-assisted on-chip mode manipulation is studied.A scheme with combining mode hybridization and Hamiltonian-hopping-assisted mode order conversion is proposed to realize mode polarization manipulation:by using mode hybridization,the questions of mode polarization manipulation can be converted into mode order manipulation.Then hopping-assisted Hamiltonian evolutions enabled chiral mode polarization converter and non-chiral polarization rotator are designed and verified in experiments.A method of achieving the mode exchange between arbitrary order transverse-electric and transverse-magnetic mode is proposed:With combining mode hybridization and metasurface enabled mode order conversion,the devices for exchanging 0?3 order transverse-electric and transverse-magnetic mode are designed and simulated,and a polarization rotator for transverse-electric and transverse-magnetic fundamental modes is verified in experiment.