Ultra-compact and broadband silicon polarizer employing a nanohole array structure

An ultra-compact and broadband transverse magnetic (TM)-pass polarizer is experimentally demonstrated using a photonic crystal nanohole structure. By engineering the period of the circular holes, the fundamental transverse electric mode is suppressed due to the bandgap of the nanohole array, while the T M ₀ mode propagates with a negligible insertion loss. Simulation results predict that the bandwidth of the device can reach 245 nm with a 33 dB polarization extinction ratio (PER). In the experiment, an insertion loss <1.2d B for the T M ₀ mode and a PER over 20.8 dB are demonstrated in a 70 nm wavelength range from 1520 to 1590 nm, mainly limited by the grating couplers used for fiber-to-chip coupling. The fabricated device is compact with a total length of 7.21 µm.