The enhanced optical coupling in a quantum well infrared photodetector based on a resonant mode of an air-dielectric-metal waveguide

The hybrid structure consisting of periodic gold stripes and an overlaying gold film is proposed to enhance the optical coupling of a quantum well infrared photodetector. An air-dielectric-metal waveguide is formed when the hybrid structure is integrated on the top of the quantum well detector with the substrate being removed. Finite difference time-domain method is used to numerically obtain the reflection spectrum and the field distribution of the waveguide. The results show that a strong electric field component is induced in parallel to the growth direction of quantum well when the waveguide resonant mode occurs at the detective wavelength of the quantum well infrared photodetector. The relationship between the structural parameters and the resonant wavelength is derived by using the effective refractive index method of the air-dielectric-metal waveguide. A high coupling efficiency can be obtained and the performance of the QWIP can be greatly improved.