The Study Of Infrared Circular Polarization Detection Based On Integrated Quantum Well Infrared Photodetectors

Infrared polarization detection can enhance the detection of faint targets,greatly suppress the interference of clouds and stray light,and improve the clarity of targets.It has important applications in remote sensing detection,meteorological monitoring,anti-jamming imaging,molecular chirality monitoring and space optical communication,etc.Among various infrared polarization detection methods,the on-chip integrated pixel-separated polarization detector can detect in real time,avoid mechanical movement,and has the advantages of simple structure,high stability,integration and miniaturization.However,the physical principle,theoretical methods and regulation mechanism of the integrated structure of the miniature circular polarizer and the detection material are not clear yet.The performance and polarization extinction ratio of the infrared polarizer and other key properties need to be improved.The material and device process of quantum well infrared detector is very mature,with high uniformity,repeatability and easy integration.It is a better choice of low cost,large array and high performance infrared polarization(linear polarization,circular polarization)focal plane detection.However,the quantum efficiency of quantum well infrared detectors is low due to the intersubband transition mechanism based on conduction band,which restricts the development of quantum well infrared detectors.With the development of chiral metamaterials,dielectric metamaterials and micro-nano technology,the amplitude,phase,polarization and photon mode of light can be effectively manipulated.This provides a new way for integrated infrared circular polarization detector.This thesis mainly uses asymmetric metamaterials,plasmon microcavities and medium metasurfaces and other photonic micro-nano structures to realize integrated quantum well infrared circular polarization detection,and effectively enhance the performance of the detector.The main research of the paper is:an integrated quantum well infrared circular polarization detection based on asymmetric metamaterials,the faceted plasmon microcavity resonance mode to improve the performance of the quantum well infrared detector,an infrared circular polarization detection based on birefringent effect of dielectric metamaterials.The specific contents include:1.In order to realize the integrated infrared circular polarization detection with high extinction ratio,an infrared circular polarization detector integrated with asymmetric metamaterials and anisotropic photoelectric materials was designed,which effectively improves the optical coupling efficiency and the circular polarization extinction ratio(CPER).The reflected light of the asymmetric metamaterial is destructively interferential with the cross-polarized electric field under the left-handed incident light.And the surface plasmons(SPP)with the z-direction component of the electric field is excited in the microcavity.While the reflection field under the right-handed incident light is constructively interferential,so the SPP mode cannot be excited.When the polarization absorption direction of anisotropic material is aligned with the polarization direction of the excited photonic mode,the absorption of LCP can be improved.In addition,the absorption of anisotropic materials in other directions is very low or even zero,which greatly suppress the absorption of RCP,thus improving the extinction ratio of circularly polarized light and enhancing the light absorption of the material.An asymmetric metamaterial is integrated on the quantum well infrared detector with a peak response wavelength of 10.55?m.Its peak responsivity is 0.32A/W,which is an order of magnitude higher than that of the 45°edge facet coupled device.CPER reaches 3.6.This kind of circular polarization discrimination infrared detection can be integrated with linear polarization detection to achieve full-Stokes polarimetric imaging,which can enhance target recognition,be used in circularly polarized light communication,and has a broad application prospect.2.In order to further improve the performance of quantum well infrared detectors,a plasmon microcavity quantum well infrared detector(PC-QWIP)with etched faces was studied.The plasmon microcavity can effectively couple incident light into the sub-wavelength microcavity and greatly increase the E_z electric field intensity in the active region of the quantum well,thereby significantly improving the quantum efficiency of the quantum well.However,in order to achieve effective optical coupling with this structure,the number of layers of the quantum well is very limited,there is a large ohmic loss,so the absorption of the quantum well is limited.Based on the coupled mode theory,creating facets can make the PC-QWIP closer to the critical coupling state.And increasing the number of the quantum well layers can increase the absorption rate of the quantum well and reduce the ohmic loss.Based on this principle,the faced PC-QWIP has a responsivity of 5.5 A/W at the peak wavelength of 15.5?m,which is 2.2times that of the unfaceted PC-QWIP,12 times that of the 45°edge facet coupled device.The dark current of the device is reduced by 32%due to the reduction of the photosensitive area caused by creatin facets.This method is of great significance to improve the performance of photodetector.3.Based on the birefringence effect of dielectric metasurface,a high extinction ratio of quantum well infrared circular polarization detector was designed.A high performance dielectric metasurface is designed to decompose the incident circularly polarized light(left-handed or right-handed)into two perpendicular linearly polarized light with high transmittance by using the birefringence effect and low loss characteristics.By integrating SPQWP with dielectric metasurface and setting the angle at 45°(or 135°),left-handed(or right-handed)light detection can be realized.Finite element numerical simulation was used to calculate circular polarization light absorption spectrum of the integrated device.The coupling efficiency of QWIPs,integrated with the dielectric metasurface,reaches 96%under LCP.And the peak absorption of the QWs reaches 28%.And the absorption of RCP is suppressed to a very low level.As a result,CPER reaches64 at the wavelength of 11.5?m.The designed structure can be realized by the quantum well focal plane process.It can be integrated with SPQWP,with linear polarization detection,to achieve full-Stokes polarimetric imaging.