The Enhancement Of Optical Coupling Modulated By Artificial Surface Microstructure Photon Mode

Quantum Well Infrared Detector?QWIP?is a new technology developed at the end of the 20th century.Compared with infrared detection technology of other materials,it has high repeatability,mature processing technology,good uniformity,fast response and wide detection wavelength range.The detected wavelength can be controlled by adjusting the parameters of the quantum well.High-quality,large-area uniform quantum well materials can be prepared by semiconductor process,which is easy to be used as a focal plane array.It is commonly used in imaging systems and has wide applications in defense,industry,and medical fields.Since Bell Labs developed the first QWIP,its technology has developed rapidly.At present,large-format monochrome QWIP has become mature at home and abroad.However,due to the quantum transition selection rule,only the incident light whose electric vector is perpendicular to the growth surface of the quantum well can be absorbed by the electrons in the sub-band from the ground state to the excited state,which causes it to not absorb the normal incident light.Compared with the mercury cadmium telluride detector,its quantum efficiency and detection rate are low,which restricts the development of QWIP.The use of a plasmonic microcavity can couple incident light into a quantum well capable of absorbing a local photon mode with a large vertical component.It has been experimentally proven to improve the light absorption of the quantum well,but in the microcavity,the absorption of the quantum well is only half of the absorption of the metal.Although the incident light is completely coupled into the local mode,the intensity of the actual absorption of the quantum well is not too great,and most of the incident light is lost by the metal absorption,and an effective optical signal cannot be generated.The main work is as follows:1.Theoretical analysis of plasmon microcavity structure based on coupled mode theory?CMT?,by maximizing the field enhancement and reducing the metal absorption loss in the optical cavity by optimizing the radiation characteristics of the optical antenna.This structure adjusts the absorption quality factor(Q_abs)and the radiation quality factor(Q_rad)by etching to form a plasma microcavity fault interface and tuning the fundamental resonance to a higher order mode,keeping the system in a critical coupling state.This method relies on regulating the absorption competition between the metal and the active material and maintaining a critical coupling state.As a photonic method,it is fully compatible with different plasmonic materials.2.For the problem of low efficiency of QWIP absorption,through the investigation,theoretical simulation analysis,the detector based on the plasmonic microcavity fault interface structure is designed by photonics method.The results show that compared with the traditional structure of the infrared detector,in the quantum well structure integrated by the plasmonic microcavity,the absorption of the quantum well in the long-wave infrared can be increased to 82%,and the metal ohmic loss is suppressed to 18%.3.In a GaAs thin film device integrated in a plasmon microcavity?which can be used for solar cells,also for fast light detection?,for a plasmonic cavity integrated with a GaAs device operating in the near-infrared range,near the absorption wavelength of GaAs at 880 nm,the photonic method can enhance the absorption of the active material to 78%of the incident power and suppress the ohmic loss to 20%at the wavelength close to the band gap.At a wavelength of 950 nm,the GaAs absorption is increased to56%and the metal loss is 41%.