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 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 for the 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.