Single-lobe steering of blue light with an active optical phased array

Area of Science:

• Photonics
• Optical Engineering
• Materials Science

Background:

• Integrated optical phased arrays (OPAs) are crucial for visible light applications including displays, underwater communication, and biophotonics.
• Achieving the required λ/2 emitter pitch for single-lobe emission is difficult with conventional silicon photonics due to feature size limitations.

Purpose of the Study:

• To demonstrate a novel approach for achieving single-lobe emission in visible light optical phased arrays.
• To overcome the fabrication constraints of traditional silicon photonics for OPAs.

Main Methods:

• Utilized a free-propagation region slab as a spatial filter to enable single-lobe steering at 488 nm.
• Constructed an OPA with a thermo-optically tuned end-fire waveguide array coupled to a slab grating emitter.

Main Results:

• Achieved a single-lobe beam-steering range of 52.8 degrees.
• Demonstrated an average sidelobe level of -11.6 dB.
• The proof-of-concept device achieved 15 resolvable spots, limited by the end-fire array size.

Conclusions:

• The proposed free-propagation region slab method effectively enables single-lobe beam steering in visible light OPAs.
• The demonstrated architecture is a viable proof-of-concept, with scaling simulations indicating potential for future development.
• This work advances the feasibility of integrated OPAs for advanced photonic applications.