Subwavelength polarization splitter-rotator with ultra-compact footprint.

An ultra-compact polarization splitter-rotator with a discretized subwavelength nanostructure is demonstrated on the silicon-on-insulator platform. The device has a length of only 7.92 μm. For TE0 -TE0 , a low insertion loss (<0.2  dB), low crosstalk (<-20  dB), and high extinction ratio (>40  dB) are achieved over a broad wavelength range from 1500 nm to 1600 nm. For TM0 -TE0 , the insertion loss is lower than 1 dB over 40 nm bandwidth (1530-1570 nm). The crosstalk is lower than -25  dB, and the extinction ratio is larger than 20 dB, from 1500 nm to 1600 nm.