Compact and broadband polarization rotator on thin-film lithium niobate utilizing mode hybridization

We propose and demonstrate a compact, broadband polarization rotator (PR) on a thin-film lithium niobate (TFLN) platform utilizing mode hybridization. The proposed PR has a footprint of 4 × 118 μm2. Numerically, the PR exhibits an insertion loss (IL) of 0.23 dB and an extinction ratio (ER) of 42 dB at 1550 nm, while its bandwidth for ER > 20 dB and IL < 1 dB exceeds 175 nm. The measurement result shows IL < 1 dB and ER > 19 dB in the wavelength range of 1490-1590 nm.