Compact mode converter on SOI based on a polygonal subwavelength grating structure

In this Letter, we design and experimentally demonstrate compact mode converters with a lightning-like and arrow-like polygonal subwavelength grating (SWG) structure on a silicon-on-insulator (SOI) platform, which can convert the TE 0 mode to the TE 1 and TE 2 modes, respectively. The footprints of the proposed TE 0–1 and TE 0–2 mode converters are only 4.44 × 1.3 and 5.89 × 1.8 µm 2 , respectively. The experimental results show the mode converters have a low insertion loss (<1 dB) and a broad bandwidth (>50 nm). The measured cross talks of the TE 0–1 and TE 0–2 mode converters are −7.2 dB and −10.3 dB, respectively. In addition, the proposed mode converters with the SWG structure have the advantage in fabrication, since only a one-step full-etching process is required.