Subwavelength Metal Cross Hole Structure In The Quantum Well Infrared Photodetector Applications In Simulation Studies

The detectivity of traditional quantum well infrared photodetector is low. Subwavelength metal hole microstructure can improve optical absorption efficiency of quantum-well infrared photodetector, enhancing the photodetector's detectivity.The metal possesses a large number of free electrons, which may couple with the electromagenetic waves, the coupling between free electrons and electromagnectic waves forms surface plasmon plasmon (SPP). The SPP's electric filed is localized on the metal surface and decays exponentially with the distance away from the metal surface. The perforated metal structure can excite the SPP mode on its surface and have unique optical properties, for example:enhanced optical transmission (EOT), optical antenna, negative refraction, enhanced fluorescence etc. Today it has become one of the research hot topics. Subwavelength metal microstructure is the main method of exciting and controling SPP mode. The photodevice of subwavelength metal microstructure of SPP can improve the performance of the tranditional devices, and still can produce some novel physical phenomenon and realize new device functionsIn this paper, the near-field enhanced transmission of periodic sunwavelength metal cross-hole arrays is studied. We simulate the optical properties of subwavelength metal hole arrays from Finite Diffence Time-Domain (FDTD).1) Light incidents from air-metal-quantum well material (front incidence), the relationship of surface plasmon plariton (SPP), localized surface plasmon (LSR) and enhanced optical transmission (EOT) are studied. We found that localized surface plasmon mediates the coupling between the incident light and plasmonic structure, and the surface plasmon plariton provides long-lived resonance, increasing photon resonance lifetime.2) Light incidents from quantum well-metal-air (back incidence), the metal holes are open, surface plasmon plariton, localized surface plasmon and Fabry-Perot cavity are studied, which may affect the near-field electric intensity. When the metal is thin, the reflection spectra of light back incidence is identical to the front incidence of light. But the near-field electric intensity of light back incidence is higher than the electric intensity of light front incidence. In the structure of light back incidence, we utilize the light from metal-quantum well side, so we can thicken the metal.3) The light that transmits to the air won't couple with electrons in the quantum well, so we design another kind of coupling structure which is closed on another side of the hole. Then the surface plasmon plariton, localized surface plasmon and Fabry-Perot cavity are studied, which may affect the near-field electric intensity. In the quantum-well place, the electric component in the z direction is high, which enhances the optical coupling efficiency with the electrons.For couplers with other different hole shapes, similar analysis can be performed.