A Six Bit Silicon Nitride Optical True Time Delay Line for Ka-Band Phased Array Antenna

A six-bit optical true time delay unit with a delay tuning increment of 1.42 ps was designed and fabricated on silicon nitride platform, which can be utilized in Ka-band phased array antenna systems. The delay unit consists of seven thermo-optical switches and six waveguide delay lines with different lengths. By changing the states of the thermo-optical switches, 64 stages of discrete time delays varying from 0 to 89.6 ps has been obtained. In addition, as the waveguide delay independence on the modulation frequency, so the designed silicon nitride delay unit can be applied in microwave applications with broader bandwidth.