Near infrared filtering properties in photonic crystal containing extrinsic and dispersive semiconductor defect

In this work, near infrared filtering properties in a transmission narrowband filter are theoretically investigated. The filter is a defective photonic crystal of (LH)^ND(HL)^N, where N is the stack number, L is SiO₂, H is InP, and defect layer D is an extrinsic semiconductor of n-type silicon (n-Si). It is found that there are multiple transmission peaks within the photonic band gap (PBG) as the defect thickness increases. The filtering position can be changed by varying the doping density in n-Si. That is, the peak (channel) wavelength is blued-shifted when the doping density increases. In the angle-dependent filtering property, the channel wavelength is also blued-shifted as the angle of incidence increases for both TE and TM waves. These filtering properties are of technical use in the applications of semiconductor optoelectronics.