Planar waveguides with less than 01 dB/m propagation loss fabricated with wafer bonding

We demonstrate a wafer-bonded silica-on-silicon planar waveguide platform with record low total propagation loss of (0.045 ± 0.04) dB/m near the free space wavelength of 1580 nm. Using coherent optical frequency domain reflectometry, we characterize the group index, fiber-to-chip coupling loss, critical bend radius, and propagation loss of these waveguides.