Antennas are important components in optical phased arrays. However, their far-field performance deteriorates when random phase noise is introduced because of fabricating errors. For the first time, we use a finite-difference time-domain solution to quantitatively analyze the far-field characteristics of Si and Si₃N₄ antennas considering process errors. Under rough surface conditions based on a fishbone structure, we find that the quality of the main lobe of the Si antenna deteriorates badly, with −0.87 dB and −0.51 dB decreases in the sidelobe level and 5.78% and 3.74% deteriorations in the main peak power in the φ (phase-controlled) and θ (wavelength-controlled) directions, respectively. However, the Si₃N₄ antenna is only slightly impacted, with mere 0.39% and 0.71% deteriorations in the main peak power in the φ and θ directions, respectively, which is statistically about 1/15 of the Si antenna in the φ direction and 1/5 in the θ direction. The decreases in the sidelobe level are also slight, at about −0.08 dB and −0.01 dB, respectively. Furthermore, the advantages of the Si₃N₄ antenna become more remarkable with the introduction of random errors into the waveguide width and thickness. This work is of great significance for the design and optimization of OPA chips.

An aluminum nitride hybrid waveguide is proposed to reduce the challenges brought on by high temperature sensitivity of microresonator-based devices. The waveguide is temperature–insensitive (athermal) and has an effective thermo-optic coefficient value of ±2 × 10 ⁻⁶ /K in the wavelength range of 1412 to 1800 nm. It exhibits anomalous dispersion of less than 96 ps/nm/km over octave in the range of 1540 to 3234 nm. The nonlinear coefficient of the aluminum nitride waveguide is enhanced by the strong nonlinearity of titanium oxide. Application of the athermal waveguide in the optical frequency comb is simulated to prove its superior thermo-optic performance.