High-resolution arrayed waveguide grating-assisted passive optical phased array for 2D beam steering.

Advanced two-dimensional (2D) beam steering is essential for unlocking the full potential of terahertz (THz) systems in future 6G communications and high-resolution imaging. However, achieving wide-angle, high-speed, and high-precision 2D beam control within a compact THz platform remains a significant challenge. In this work, we experimentally demonstrate an optoelectronic 2×2 THz antenna array that enables flexible 2D beam steering, beam hopping, and beam scanning around the 300 GHz band. This work employs a 2×2 microstrip patch antenna (MPA) array directly driven by InGaAs/InP UTC-PDs on a silicon carbide (SiC) substrate. The relative phases of the four radiating elements are precisely programmed using an optical phased array (OPA), which provides fully decoupled and low-latency phase control in the optical domain. Experimentally, we demonstrate 2D beam steering and 2D beam hopping among three representative directions at a polar angle of 25∘ and azimuth angles of 60∘, 180∘, and 300∘. Furthermore, continuous 2D beam scanning at a fixed polar angle of 25∘ is achieved, enabling a full 360∘ azimuth sweep within 0.43 s while maintaining high beam quality. These results confirm that the proposed UTC-PD based 2×2 MPA array provides a practical and robust approach for 2D THz beam manipulation, and offers strong potential for future 6G wireless links and THz imaging applications.

Optical phased arrays (OPAs) have received considerable attention as solid-state beam scanners. However, conventional OPAs that actively control the phase difference between arrays are characterized by excessive power consumption for high-precision beam emission. In this study, we fabricated an OPA comprising Bragg grating and arrayed waveguide grating (AWG). Multi-mode waveguide is used in AWG to reduce the effect of manufacturing error. This device realizes wide and high-resolution two-dimensional beam steering only by sweeping wavelength. FWHM of the emitted beam is 0.534° × 2.27°, and the steering range is 43.9° × 13.5° with 1/64 of the power consumption of conventional OPA.

This paper outlines the design, performance and application of a highly-integrated stacked wavelength selective switching (WSS) technology platform based on 4k liquid crystal on silicon (LCOS) devices and two-dimensional (2D) beam steering.

On-chip optical phased arrays (OPAs) are the enabling technology for diverse applications, ranging from optical interconnects to metrology and light detection and ranging (LIDAR). To meet the required performance demands, OPAs need to achieve a narrow beam width and wide-angle steering, along with efficient sidelobe suppression. A typical OPA configuration consists of either one-dimensional (1D) linear or two-dimensional (2D) rectangular arrays. However, the presence of grating sidelobes from these array configurations in the far-field pattern limits the aliasing-free beam steering, when the antenna element spacing is larger than half of a wavelength. In this work, we provide numerical analysis for 2D circular OPAs with radially arranged nano-antennas. The circular array geometry is shown to effectively suppress the grating lobes, expand the range for beam steering and obtain narrower beamwidths, while increasing element spacing to about 10 μm. To allow for high coupling efficiency, we propose the use of a central circular grating coupler to feed the designed circular OPA. Leveraging radially positioned nano-antennas and an efficient central grating coupler, our design can yield an aliasing-free azimuthal field of view (FOV) of 360°, while the elevation angle FOV is limited by the far-field beamwidth of the nano-antenna element and its array arrangement. With a main-to-sidelobe contrast ratio of 10 dB, a 110-element OPA offers an elevation FOV of 5° and an angular beamwidth of 1.14°, while an 870-element array provides an elevation FOV up to 20° with an angular beamwidth of 0.35°. Our analysis suggests that the performance of the circular OPAs can be further improved by integrating more elements, achieving larger aliasing-free FOV and narrower beamwidths. Our proposed design paves a new way for the development of on-chip OPAs with large 2D beam steering and high resolutions in communications and LIDAR systems.

We report a simple concept to implement a single-wavelength beam steering based on a liquid-cladded one-dimensional (1D) optical phased array (OPA). The beam steering was realized by modifying the waveguide mode effective index through replacing the liquid upper claddings. A prototype of a 32-channel liquid-cladded OPA was fabricated and characterized. Owing to the high refractive index range of liquids (>0.625), a maximum steering angle of >10∘ was achieved with the liquid range from 1.0 to 1.63 at a wavelength of 940 nm. Moreover, the liquid-cladded OPA reveals a quasi-continuous beam steering range of >29∘ by combining the liquid cladding tuning and discrete wavelength tuning of λ=785nm, 852 nm, and 940 nm. Further integration with optofluidic systems offers the OPA potential for low power consumption and all-fluidic beam steering operating at a single wavelength.

We present high-performance integrated optical phased arrays along with first-of-their-kind light detection and ranging (LiDAR) and free-space data communication demonstrators. First, record-performance optical phased array components are shown with low-power phase shifters and high-directionality waveguide grating antennas. Then, one-dimensional (1-D) 512-element optical phased arrays are demonstrated with record low-power operation ( $ 1 mW total), large steering ranges, and high-speed two-dimensional (2-D) beam steering ( $ 30 $\mu$ s phase shifter time constant). Next, by utilizing optical phased arrays, we show coherent 2-D solid-state LiDAR on diffusive targets with simultaneous velocity extraction at a range of nearly 200 m. In addition, the first demonstration of 3-D coherent LiDAR with optical phased arrays is presented with raster-scanning arrays. Finally, lens-free chip-to-chip free-space optical communication links up to 50 m are shown, including a demonstration of a steerable transmitter to multiple optical phased array receivers at a 1 Gb/s data rate. This paper shows the most advanced silicon photonics solid-state beam steering to date with relevant demonstrators in practical applications.

Optical phased arrays (OPAs) with the ability of dynamic beam-steering hold great promise for LiDAR applications. In contrast to mechanical scanning, OPAs have the advantage of being capable of agile beam pointing, allowing the multifunctional operation in LiDARs. In this paper, we propose a liquid crystal (LC) tunable OPA to achieve 2D beam steering. This approach enables a LC-tunable beam control in a second axis in addition to an OPA-tuning, thereby achieving 2D beam steering at a single wavelength. The LC-tunable OPA is fabricated using a standard Si photonics process and a LC process common for commercialized LC displays and LC on Si (LCOS) devices. We have fabricated samples of LC-tunable devices and LC-tunable OPA devices for 1D and 2D steering respectively and demonstrated a LiDAR using the 1D steering device. By taking advantage of non-mechanical movement of the device, a target tracking is realized by detecting a person from a camera image and irradiating the steering beam in that direction with more than 10 frames per second. With a faster 2D steering, a 3D target tracking even for multiple targets could be realized in the future.

Free-space beam steering plays an important role in ultrafast switching and scanning applications. Optical phased array (OPA) is commonly used for this function. Here we propose an alternative method to realize two-dimensional large-angle beam steering for single-wavelength light on Si platform. The steerer consists of an electrically controlled 1×N cascaded add-drop ring resonator and N off-chip emitters. Each output of the resonator connects with one emitter to emit light to free space at a certain direction. Single-wavelength light coupled in the input bus waveguide of the cascaded ring resonator can be switched among these N outputs by means of tuning the refractive index of the cascaded rings electrically and then be emitted to different directions in far field, which behaves as beam steering apparently. The steering can be one- or two-dimension, depending on the arrangement of these N off-chip emitters on the chip. Moreover, the proposed steerer can be combined with the conventional OPA for more precisely beam steering. A 1×9 cascaded ring resonator was fabricated on hydrogen amorphous silicon platform for proof of concept demonstration.

Optical phased array (OPA) on silicon platform is developed as a hot topic in the past decade. In order to achieve both large field of view (FOV) and high side mode suppression ratio (SMSR), large-scale antenna with spacing of half wavelength is usually required, resulting in large footprint and complex scanning design. Recently, OPAs with nonuniform antenna are proposed as efficient solutions to achieve large FOV with simplified layout. Here, we analyze the performance of various OPAs with different nonuniform antenna designs. In addition, a genetic algorithm optimization method is further proposed for nonuniform antenna design. OPA with the proposed nonuniform antenna is simulated with a steering range of ±50° and SMSR of 11.3dB.

Summary form only given. Advances in arrayed waveguide gratings (AWGs) allow monolithic integration of a wide variety of devices using guided-wave photonics. One particular application of interest is beam steering. Beam steering devices implemented in a guided-wave architecture are attractive in optical signal processing, packet switching and laser displays. Various means of achieving efficient beam steering have been explored to date. Our approach is based on using quantum well intermixing technology to integrate a tunable DBR laser with an AWG device.

The silicon photonic optical phased array (OPA) featured by high integration and agile beam steering exhibits greatly potential application in optical wireless communication (OWC). In this article, we demonstrate high-data-rate and long-range OWC using an integrated Silicon-Silicon Nitride OPA chip with 12 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> large aperture. The OPA chip constituted by 128 waveguide grating antennas at nonuniform spacing is employed for wide-steering and small-divergence solid beam steering. In the experiment, we demonstrated 100° wide range communications in horizontal direction via antenna phase tuning. To our best knowledge, 100° is the widest cover range in the reported OPA-based OWC systems. Moreover, the OPA chip is also utilized to achieve up to 32 Gb/s low BER transmission of non-return-to-zero (NRZ) signal over 54 m free space distance. In addition, we also successfully demonstrated more than 50 Gb/s PAM4 signal transmission by measuring clear eye diagrams at the horizontal direction of 0° and 50° over 10 m. Thanks to agile beam steering of the OPA, switching time among arbitrary positions in multi-targets communication can be less than 27 μs. By virtue of tiny beam divergence 0.021° × 0.029° emitted from the OPA, data transmission switching between two targets spaced at 3.5 cm over 20 m can be achieved accurately. The experimental measurement shows the sidelobe crosstalk from the adjacent target channel is less than −25.2 dB. Our demonstrations validate the feasible implementation of the silicon-based OPA in the high-data-rate and wide-steering-range OWC system.

In this work, we present two-dimensional beam steering in the near-infrared using a SiN integrated circuit, containing optical phased arrays. Beam steering was achieved over a range of 17.6° × 3°, at a fixed wavelength of 905 nm. The first dimension was steered via phase differences between the optical phased array channels. The second dimension was accessed by actively switching between various optical phased array sub-devices containing output diffraction gratings with different periods. The characterisation was performed on a wafer-level test station.

We demonstrate a 63-channel grating-lobe-free optical phased array, in which end-fire antennas were fabricated with a pitch of 775 nm to eliminate grating lobe. Phase mismatch was configured to suppress the optical crosstalk in the dense waveguides. Two-dimensional beam steering within 16&deg;&times; 2.7&deg; were presented by thermal phase shifting and wavelength tuning.

2-D optical phased array (OPA) antenna based on a liquid crystal on silicon (LCOS) spatial light modulator is introduced. Diffraction efficiency of the 1-D OPA for fine angle beam steering and 2-D OPA for aberration correction is characterized experimentally and by computer simulation. Excellent agreement between the simulation, measurement and empirical model is observed. Large aperture transmitter for long distance free space communication is analyzed by wave optics simulation. The system performance for beam steering and correction for wavefront aberration in large aperture transmitter is discussed.

The alignment of a receiver with a pencil beam in a wireless optical power transfer (WOPT) system employing a resonance beam charging (RBC) technology limits the establishment of a resonance cavity. Accurate tracking necessitates precise and dependable monitoring, which requires the exact placement of transmitting and receiving devices. Herein, we present a concept of a two-dimensional (2D) beam steering mechanism for RBC-based WOPT systems utilizing dispersed laser beams. The proposed approach allows a significant improvement, including reduction of scanning times and minimization of errors, in relation to conventional pencil-beam-based systems. Experimental results reveal 14% faster acquisition time efficiency, an 18% improvement in pointing accuracy, and a 24% enhancement in tracking accuracy. These results establish the prerequisites for the implementation of dispersed beam steering in the RBC-based WOPT system. This capability empowers the system to charge movable devices and Internet of Things devices consistently in smart factories.