Silicon nitride optical phased array based on a grating antenna enabling wavelength-tuned beam steering

Area of Science:

• Photonics and Optical Engineering
• Materials Science for Integrated Optics

Background:

• Silicon nitride (SiN) optical phased arrays (OPAs) are emerging as a key alternative to silicon-based devices.
• Limited research exists on the wavelength-tuned beam steering capabilities of SiN OPAs.

Purpose of the Study:

• To investigate and optimize wavelength-tuned beam steering in SiN OPAs using grating antennas.
• To explore the spectral beam emission characteristics influenced by resonant cavity thickness.

Main Methods:

• Theoretical and experimental analysis of two SiN OPA devices with varying resonant cavity thicknesses (SiN core and buried oxide layer).
• Characterization of spectral emission and beam steering angles.
• Examination of optical thickness influence on antenna spectral response.

Main Results:

• Both fabricated SiN OPAs achieved a longitudinal beam steering angle of 7.4° for wavelengths between 1530-1630 nm.
• A device with a thicker buried oxide layer showed limited steering performance over a broad spectral range.
• Grating antenna efficiency was maximized when optical cavity thickness was an odd multiple of a quarter wavelength.

Conclusions:

• The optical thickness of the resonant cavity significantly impacts the spectral response and steering performance of SiN OPAs.
• Designing SiN OPAs with cavity optical thickness at odd quarter-wavelength multiples is a viable strategy for stabilized spectral operation.