Near-Infrared Enhanced Silicon Photodetectors Based On Metasurface

A metasurface is composed of a series of subwavelength unit structures arranged periodically.By regulating the size,shape,and spatial arrangement of the microstructure,precise and flexible control of electromagnetic wave phase,amplitude,polarization,and other properties can be achieved,leading to important technological breakthroughs and application innovations in fields such as information and optics.Based on the generalized Snell’s law,the gradient refractive index metasurface phase control and other basic principles,this thesis proposes an integrated structure of metasurface and silicon photodetector.By changing the deflection angle of incident light,the absorption length of light can be increased to improve the absorption rate and overcome the limitation of intrinsic properties of materials on the detection efficiency of nearinfrared waveband.The main research results are as follows:1.The phase control principle of the gradient refractive index metasurface was simulated,and a method for constructing a beam deflection-type metasurface structure was proposed.Under the condition of 1064 nm plane wave incidence,silica nanocolumns on silicon dioxide were used as the unit structure of the metasurface.The angle deflection from 5° to 75° was simulated with a unit structure period of 250 nm,and the influencing factors of the metasurface deflection performance were analyzed.The deflection performance of the angle deflection metasurface is optimized by adjusting the cell structure parameters,and the deflection efficiency was increased from 59.64%and 61.10%to 81.04%and 67.63%when the deflection angles were 60° and 75°,respectively.2.The absorption rate of the light beam deflected by the metasurface at different silicon material thicknesses was simulated.A three-layer structure of metasurface-silicon dioxide-silicon was constructed,and the absorption rate at different silicon material thicknesses was simulated.The absorption rate was highest when the angle deflection was 30°.For a 500 μm thick silicon substrate,the absorption rate was increased by 2.41%compared to the vertical incidence case.The optimized structure improved the transmittance of light into the silicon material.At an angle deflection of 50°,the absorption rate at a thickness of 500 μm increased by 5.09%compared to the vertical incidence case.3.A full-silicon type angle deflection metasurface from 30°to 55°was simulated.When the deflection angle was 55°,the absorption rate at a thickness of 500 μm was increased by 12.5%compared to the vertical incidence case,solving the problem that the deflection angle is difficult to control due to the refractive index mismatch between the metasurface structure and the silicon material.4.A test system was constructed based on LabVIEW virtual instruments,which realized remote control,Ⅳ testing,and visualization and persistence of test data for the Keithley 6517B electrometer.The test system was verified through experiments,and issues such as drop points and repeated points were solved by adjusting the delay parameters.