| With the development trend of interconnection of all things and data ubiquity in the 5G era,people’s growing network demands put forward higher requirements for the capacity and speed of optical communication.As a key device in optical communication system,InGaAs-PD has the advantages of high speed,high quantum efficiency and easy integration,and is widely used in communications,military,aerospace and other fields.As an important indicator to measure the performance of photodetectors,there is a mutually restrictive relationship between bandwidth and quantum efficiency,and it is usually necessary to increase the thickness of the absorber layer in order to improve the quantum efficiency of the device,and the thicker absorber layer will increase the transit time of the carrier,resulting in a decrease in bandwidth.How to overcome this constraint so that photodetectors with a thinner absorption layer still have high quantum efficiency while maintaining high-speed performance is a problem that needs to be solved in InGaAs-PD research.With the rapid development of micro-nano processing technology,it has been found that the nano-optical antenna structure has special optical resonance and local field enhancement effects,which can realize the regulation of the light field at the nanoscale.By designing a reasonable nano-optical antenna structure on InGaAs-PD,the optical absorption capacity of the device can be enhanced without changing the thickness of the absorbing layer,providing a way to achieve high-speed,high-quantum efficiency InGaAs-PD.In this paper,the optical absorption characteristics of InGaAs photodetectors based on nano-optical antenna structures are mainly analyzed,and the main research contents and innovation points are as follows:1.Using the time domain finite difference method,the scattering and absorption characteristics of nano-optical antenna particles of metal and dielectric materials in the range of 0.9 μm to 1.7 μm short-wave infrared band are studied in depth.The influence of structural parameters such as material,size and morphology on the optical resonance properties of particles is analyzed.Matlab programs were written by long wavelength approximation methods to solve multipolar moments of dielectric nanoparticles,and the contribution of different polar moments to scattering efficiency was further analyzed.The research content provides a reference for the application of nano-optical antennas in the short-wave infrared range.2.An InGaAs-PD based on spherical Ag nanoparticle array optical antenna structure is proposed.By adjusting the size and arrangement period of the particles,the metal nano-optical antenna structure with the best enhancement effect of InGaAs-PD optical absorption at a wavelength of 1550 nm was obtained.This structure allows the device to achieve high optical absorption gain in the 1130 nm to 1560 nm bands.The results show that when the spherical Ag nanoarray structure with a diameter of D=0.38 μm and a period P=0.75 μm is laid out on the top layer of InGaAs-PD with an absorption layer of 800 nm,the optical absorption rate is increased by 29.6%compared with the reference structure PD without nanoparticles.3.An InGaAs-PD based on the structure of a cylindrical InP nanoparticle array optical antenna is proposed.By adjusting the particle size,arrangement period and height,the dielectric nano-optical antenna structure with the best enhancement effect of InGaAs-PD optical absorption at a wavelength of 1550 nm was obtained.And the structure can obtain a high optical absorption rate gain near the wavelength of 1000 nm and in the band range of 1245 nm to 1660 nm.The results show that when the cylindrical non-doped InP nanoparticle array structure with a diameter of D=0.44 μm,a period P=0.74 μm,and a height of H=0.6 μm is laid out on the top layer of InGaAs-PD with a thickness of 800 nm,the optical absorption rate is increased by 54.9%compared with the reference structure PD without nanoparticles.4.A new type of NiO/InGaAs-PD is designed with a nanoporous array structure to improve the optical absorption of the device by using its optical capture effect.The transmittance of NiO films of different thicknesses was calculated,and the absorption rate of NiO/InGaAs-PD of nanoporous arrays with different diameters and depths was studied.The results show that when cylindrical nanopores with diameter D=0.5 μm,etching depth H=0.9 μm and period P=0.75 μm are arranged on the top layer of NiO/InGaAs-PD with an absorber layer thickness of 800 nm,the optical absorption rate is 19.7%higher than that of the reference structure PD without nanopores.Experimentally,a NiO/InGaAs-PD was prepared,and the transmittance of the NiO film with a thickness of 100 nm was measured to be above 85%from 1470 nm to 1600 nm,which was well consistent with the simulation results. |
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