Photonic Filters on the lithium-niobate-on-insulator With Ultra-High Sidelobe Suppression Ratio

We present a box-like photonic filter on the x-cut lithium-niobate-on-insulator (LNOI) platform made using cascaded six identical multimode waveguide gratings (MWGs) with a high sidelobe suppression ratio of ~60dB and a maximum insertion-loss is 0.6dB for light in the telecom C-band near 1550nm.