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

Abstract

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.

Design of Ka-Band Phased Array Antenna with Calibration Function

“…The Ka-band T/R component is an important part of the active phased array radar antenna [14][15][16]. Each T/R channel includes receiving channel, transmitting channel and public channel.…”

Integrated contra-directionally coupled chirped Bragg grating waveguide with a linear group delay spectrum

“…In the traditional phased array system based on phase shifters, beam dispersion occurs in the wideband operation mode owing to the correlation between phase and frequency. In contrast, phased array systems based on true time delay can achieve broadband beamforming because the time delay is frequency-independent [ 1 ]. True time delay can be achieved by means of electric delay or microwave photonic delay.…”

“…Integrated optical true time delay lines can be implemented using various approaches such as switches, optical ring resonators (ORRs), photonic crystal waveguides (PhCWs), and chirped Bragg grating waveguides. In switch-based delay lines, discrete delays can be realized by connecting switches with waveguides of different lengths and the time delay can be tuned by changing the switching state [ 1 , 9 , 10 ]. This method can achieve accurate delay, but the difficulty lies in the calibration of switches.…”