Broadband silicon polarization beam splitter based on Floquet engineering

A broadband silicon polarization beam splitter (PBS) is proposed and experimentally demonstrated based on Floquet-engineered directional couplers. The total length of the coupling structure is 20 μm. By periodically modulating the waveguide widths of the directional couplers, the power exchange between the two waveguides for the transverse-electric (TE) mode is suppressed, while the power coupling for the transverse-magnetic (TM) mode is enhanced. The fabricated PBS exhibits polarization extinction ratios (PERs) >20 dB for both polarizations over a broad wavelength range of 1483-1620 nm. Additionally, the measured insertion losses (ILs) are 0.15 dB and 1.2 dB at 1550 nm for TE and TM polarizations, respectively.