Optical Phased Array Technologies for Beam Steering

Optical phased arrays (OPAs) constitute a class of solid-state beam steering devices that direct light by controlling the relative phase across an array of emitters. By electronically tuning phase shifters integrated on photonic circuits, OPAs achieve rapid, inertia-free scanning over a defined field of view, overcoming the limitations of mechanical mirror systems. Central design challenges include balancing steering range, beam divergence and side-lobe suppression, with denser emitter spacing and advanced calibration methods mitigating unwanted beams. Silicon photonics, silicon nitride waveguides and hybrid platforms have enabled large-scale integration of hundreds to thousands of phase-tunable elements, while micro-electromechanical hybrids offer additional two-axis or random-access control. Applications span three-dimensional imaging and ranging, secure free-space communications and projection, with field-of-view angles reaching tens of degrees and resolvable spots in the tens of thousands. Recent advances in materials, low-power phase shifters and aperiodic emitter distributions have further expanded practical performance, bringing compact, energy-efficient beam steering into autonomous vehicles, robotics and consumer electronics.

Research from Nature Portfolio

Recent studies have demonstrated integration of active OPAs with micro-electromechanical structures to achieve two-dimensional beam steering without bulky optics. One effort combined a 905 nm silicon nitride phased array with a piezoelectric-actuated micro-cantilever, yielding one-axis electronic scanning of 17° and independent mechanical tilt spanning up to 40° in the orthogonal axis. In another development, a 128×128-element focal plane switch array of grating antennas and MEMS-actuated optical switches realised a 16 384-pixel LiDAR system with a 70°×70° field of view, 0.6° addressing resolution and sub-0.05° beam divergence. The system supports random-access beam addressing at sub-megahertz rates and centimetre-scale range resolution, highlighting the potential of monolithic photonic chips for high-performance solid-state ranging and imaging.

Optical Phased Array Technologies for Beam Steering publication trend

The graph below shows the total number of articles in optical phased array technologies for beam steering across all publications each year (not limited to Nature Index journals).

Technical terms

Optical phased array (OPA): A solid-state device comprising multiple coherent emitters whose relative phases are electronically tuned to steer and shape a light beam without mechanical motion.

Field of view (FOV): The angular span over which an OPA can effectively direct its output beam.

Side-lobe suppression ratio (SLSR): The intensity ratio between the main beam and the most energetic undesired side-lobe, indicating beam quality.

Grating lobe: An unwanted replica of the main beam arising at specific angles due to periodic spacing of emitters.

Phase shifter: An integrated element that adjusts the optical phase of each emitter, enabling constructive interference at the desired angle.

Beam divergence: The angular width of the emitted beam, typically defined at full width at half maximum (FWHM).

MEMS (micro-electromechanical systems): Miniaturised mechanical components integrated with electronics for precise actuation, such as tilting or switching beam emitters.

Phase calibration: The process of correcting emitter phases to compensate for fabrication variations or crosstalk and enhance beam steering performance.

References

1. Active optical phased array integrated within a micro-cantilever. Communications Engineering (2024).
2. A large-scale microelectromechanical-systems-based silicon photonics LiDAR. Nature (2022).
3. Half-wavelength-pitch silicon optical phased array with a 180° field of view, high sidelobe suppression ratio, and complex-pattern beamforming. Optica (2024).
4. Grating-lobe-free optical phased array with 2-D circular sparse array aperture and high-efficiency phase calibration. Nanophotonics (2024).