Emerging Trends in Optical Phased Arrays

Dear Colleagues,

In recent years, optical phased arrays (OPAs) on a nanophotonic chip have garnered widespread attention due to their increasing applications in beam steering, spatial phase modulation, and beam shaping area such as light detection and ranging (LiDAR), 3D imaging, optical wireless communications (OWC), beam shaping, projection and 3D holographical displays, etc. Chip-scale OPAs based on silicon photonics are fabricated using CMOS-compatible processes, which can be compact, robust, and inexpensive. Emerging trends in integrated OPA include nanophotonic antenna design, new ideas for phase shifter, uniform/non-uniform arrays, on-chip manipulation of optical waves, and so on.

The light that propagates on planar waveguides can diffract off the surface once impinging on a grating structure. Grating couplers, commonly used to couple the light into and outside of the chip, have been the structure of choice to realize optical antennas in phased arrays. Most integrated OPAs developed thus far employ waveguide grating antennas with either 2D grating coupler arrays or 1D waveguide surface grating arrays. In 2D OPAs, grating couplers are compact, with a few microns in each dimension, ensuring uniformly broad radiation pattern. Conversely, the 1D OPAs employ the phase retardation scheme along the longitudinal direction (defined as the grating array direction, ψ) and the wavelength tuning scheme of the input light along the transverse direction (defined as the grating antenna direction, θ) to achieve beam steering. Electro-optic and thermo-optic effects are often used to realize variable phase shifters, since the optical phase may be adjusted by controlling the propagation speed in the waveguide.

The optical radiation from a OPA is caused by optical wave interference, which is the coherent superposition of complex-valued wave functions emitted by multiple antenna elements. The interference lobes are the main source of loss in OPAs.

This Special Issue aims to collate papers addressing both theoretical and experimental advancements in OPA, emerging applications in LiDAR, imaging, OWC, projected displays, etc. Potential topics include, but is not limited to, the following:

1. New design for OPA antenna, such as grating couplers, metasurface structures, plasmonic structures, and so on;
2. Principles for optical phased arrays (OPA);
3. OPA transmitter;
4. OPA receiver;
5. On-chip manipulation of optical waves;
6. Optimization Algorithms for phase control in beam forming and steering;
7. LiDAR based on OPA;
8. Pointing, acquisition, and tracking (PAT) in OWC based on OPA;
9. Elimination of turbulence effects of OWC in water or air;
10. Beam steering based on OPA;
11. 3D imaging and display based on OPA.

We look forward to receiving your contributions.

Prof. Dr. Caiming Sun
Dr. Liu Weiwei
Dr. Binghui Li
Guest Editors

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• silicon photonics
• optical phased arrays (OPA)
• light detection and ranging (LiDAR)
• optical wireless communications (OWC)
• phase shifter
• optical antenna
• grating coupler