Low Loss, Compact TM-Pass Polarizer Based on Hybrid Plasmonic Grating

A low-loss, compact TM-pass polarizer is demonstrated based on hybrid plasmonic grating on silicon-on-insulator platform. Since the large mode distribution mismatch and plasmonic effect significantly influence the transmission and reflection spectrum of the device, the traditional theory of Bragg grating cannot fully explain this phenomenon. Here, we proposed an analysis method which takes effective index and mode overlap together into consideration to design this polarizer. A compact length of
$2.5~\mu \text{m}$
with extinction ratio over 25 dB is realized simultaneously. Moreover, the insertion loss is only 0.088 dB, which is comparable to dielectric-based devices.