Principle And Application Of Photonic Crystal Guided-mode Resonance

Photonic crystal slabs (PCSs) are a particularly important class of photonic crystal structures, which offer great potentials in a wide range of applications like optical communications, optical information processing and optical integration, etc.. Three kinds of new optical devices are proposed based on the guided-mode resonance (also called Fano resonance) in two-dimensional (2D) PCSs. The numerical techniques including plane wave expansion method (PWE), finite-difference time-domain method (FDTD) and rigorous coupled wave analysis method (RCWA) are applied to analyze the performance of designed devices. The primary achievements are summarized as follows:1. We report the impact of the pattern layout on the performance of Fano broadband reflectors based on2D photonic crystals (PCs) on silicon-on-insulator (SOI). Two representative PC patterns including hexagonal and square are fairly compared with same buried oxide (BOX) layer thickness and equivalent refractive index of silicon layer by using3DFDTD technique. Both red-and blue-spectral shifts are demonstrated with either addition of oxide on top, and/or selective etching of the BOX below. The hexagonal pattern can offer larger bandwidth with a bit lower reflectance as compared to square one. Additionally, it is more sensitive to etching thickness.2. A large-angle polarization-independent broadband guided-mode-resonant filter is proposed based on two-dimensional honey-comb silicon photonic crystal slab with ultralow refractive-index substrate material. The broadband operating range is determined firstly based on the dispersion relationship and rigorous coupled wave analysis (RCWA). Then the impact of silicon membrane thickness and air hole size on the performance of proposed device under surface normal incidence is investigated and an optimal set of physical parameters for1.55-μm communication window is obtained correspondingly. Its performance affected by oblique incidence and polarization is also analyzed. It shows that over110-nm broad bandwidth can be obtained with beyond98%normalized transmittance under surface normal incidence. The common bandwidth of two polarizations will reduce with the increase of incident angle. But it can still cover the whole C-band window (1525nm-1560nm) with over98%normalized transmittance when the angle reaches18° 3. A dual-wavelength narrowband filter is proposed based on triangular-lattice Fano PCSs. The normalized transmission under surface normal incidence is investigated by using RCWA. The wavelength spacing between the two filtered channels can be tuned by adjusting the related parameters. Both red-and blue-spectral shifts are demonstrated. The short wavelength near1550nm can offer almost100%filtering efficiency and more than1000quality factor (Q, defined as the ratio of center wavelength to full width at half maximum).In summary, the innovation of this research work includes the demonstration of broadband reflectors, broadband filters and narrow band filters based on various lattice arrangement in2D PCSs. Owing to their simple configuration, small size, low cost and ease of integration, they offer great potentials in satisfying the new demands of next-generation opto-electronic systems.