Subwavelength grating: A new type of microphotonic waveguide and implementations to fiber-chip coupling, waveguide crossing and refractive index engineering

We demonstrate a new microphotonic waveguide principle based on subwavelength gratings. We also present several practical implementations of subwavelength waveguides, including a microphotonic fiber-chip coupler with a coupling loss as small as -0.3 dB, a waveguide crossover with an excess loss of 0.02dB/crossing and a PDL of <;;0.1 dB, and a new type of planar waveguide multiplexer.