Integrated Ultra-Low-Loss 4-Bit Tunable Delay for Broadband Phased Array Antenna Applications

We demonstrate the design, fabrication, and characterization of a 4-bit tunable delay in an ultra-low-loss Si3N4 planar platform. Temporal delays up to 12.35 ns with resolution of 0.85 ns are measured, for a total of 2.407 meters of propagation length. The TE waveguide propagation loss is measured to be (1.01 +/- 0.06) dB/m at a wavelength of 1550 nm with the lowest loss of (0.57 +/- 0.08) dB/m at 1591 nm.