Optimization of a programmable λ/2-pitch optical phased array

Area of Science:

• Photonics
• Integrated Optics
• Optical Engineering

Background:

• Achieving single-lobe emission in optical phased arrays (OPAs) is challenging due to densely spaced emitters and optical crosstalk.
• Fabrication variations and inter-waveguide crosstalk degrade the performance of OPAs, limiting their practical applications.

Purpose of the Study:

• To propose and validate a heuristic optimization method for amplitude and phase control in OPAs.
• To mitigate optical non-idealities and achieve single-lobe emission with suppressed sidelobes.

Main Methods:

• Heuristically optimized the amplitude and phase of each grating antenna in a silicon photonic integrated circuit.
• Utilized 1 mm-long gratings with 775 nm spacing for operation in the 1450-1650 nm wavelength range.
• Evaluated the two-dimensional (2D) beam-steering performance over a wide field-of-view (FOV).

Main Results:

• Achieved a wide 2D beam-steering range of 110° × 28° within a 127° × 47° FOV.
• Demonstrated an average sidelobe suppression of 8.2 dB, concentrating 34.5% of power into the main lobe.
• Reached peak sidelobe suppression of 14.5 dB with 50% power in the main lobe.

Conclusions:

• The heuristic optimization method effectively corrects optical non-idealities in OPAs.
• The approach enables alias-free out-of-plane emission, suitable for advanced photonic applications.
• This technique significantly improves the beam quality and power concentration in densely spaced emitter arrays.