Design of high-quality polarization-independent Fabry–Perót interferometers in an air-hole silicon photonic crystal

Two high-quality (high-Q) polarization-independent Fabry–Perót interferometers (PIFPIs) based on the self-collimation (SC) effect in an air-hole silicon photonic crystal (PhC) are designed and numerically demonstrated. Two kinds of PhC mirrors with high reflectivity are found, which can both constitute high-Q Fabry–Perót interferometers (FPIs). Although the transmission spectra of the FPIs are polarization dependent due to the birefringence of the PhC, the same resonance frequencies for both TE modes and TM modes in the high-Q FPIs can be obtained using the polarization peak matching method. For the first PIFPI, the Q factors for TE and TM modes are 841.7 and 427.5, respectively, which are much higher than those in existing works. For the other PIFPI, the Q factors for the TE and TM modes are up to 1694.8 and 1807.7, respectively. For the operating wavelength of 1550 nm, the dimensions of these two PIFPIs are about 25.1 × 12.6 µ m . With their small dimensions and high Q, the proposed PIFPIs can be used as sharply tuned optical filters or as spectrum analyzers, and may play an important role in future photonic integrated circuits.