CC BY
14Laser beam steering via optical phased array antenna
N.S. Laskavyi1'2*, A.A. Zhuravlev1'3
1- Public Joint Stock Company "Perm Scientific-Industrial Instrument Making Company" (PJSC "PNPPK"),
106, 25th October St., Perm, Russia, 614007 2- Perm National Research Polytechnic University, 29 Komsomolsky Ave., Perm, Russia, 614990 3- Perm State National Research University, 15 Bukireva St., Perm, Russia, 614068
Laser beam steering in power transmission and communication systems through free-space optical channel and light detection and ranging (LiDAR) has gained significant popularity in recent decades due to the advantages of photonics such as high-speed performance, wide bandwidth, electromagnetic immunity and security of communication channels.
Now, in most cases when it is necessary to change the direction of propagation of an optical beam, we use spatial optics or electromicromechanical systems. This study examines a different principle for steering a laser beam using an optical phased array (OPA). It consists of adding the radiation patterns of individual coherent optical emitting elements located in a one-dimensional or two-dimensional array and forming an interference pattern in the far field. The shape and direction of the total radiation pattern is controlled by adjusting the amplitude and phase of a separate radiating element. This method combines the theory and practice of developing radio frequency phased arrays (PA) and the advantages of photonics. Now, we distinguish fiber optic, microelectromechanical, liquid crystal, metastructural and solid-state (based on photonic integrated circuits) OPAs.
PIC OPA stand out as a promising solution for future dynamic beam steering systems, since this technology allows achieving high stability, beam steering speed and accuracy without mechanical movement of elements. This makes PIC OPA robust and unaffected by external factors such as acceleration.
PIC OPA generate narrow laser beams and have a wide scanning angle with tuning speeds in the range from MHz to GHz. The most common and developed PIC OPA now are silicon-based PIC, since this technology is compatible with the developed infrastructure of the complementary metal-oxide-semiconductor (CMOS) process [1-4]. However, the main disadvantage of this technology is the control of the phase of the optical signal due to the thermo-optical effect, which leads to increased inertia of laser beam control, the need to remove heat from the phase-shifting elements and relatively high power consumption.
One of the promising technologies is the use of lithium niobate LiNbO3, the main advantage of this material can be considered the control of the phase of the optical signal due to the electro-optic effect. Such technologies for the formation of the topology of the PIC as proton exchange and titanium diffusion can be used in the production of PIC OPA. Nevertheless, due to the low contrast of the structures, these technologies do not allow the implementation of close waveguide channels necessary for the formation of a directional pattern with a small number of side maxima. Moreover, it is impossible to comply with the main requirement of the OPA: the distance between the radiating elements should not exceed half the wavelength of the electromagnetic radiation used (A/2). For forming elements located relative to each other at a distance of A/2 or less, it is possible to use a technology based on thin-film lithium niobate. Research in this area is already underway [5,6], in the author's opinion, this technology is the most promising in the development of OPA.
[1] Y. Guo, Y. Guo, C. Li, H. Zhang, X. Zhou, L. Zhang, Integrated Optical Phased Arrays for Beam Forming and Steering, Appl. Sci. 11(9), 4017 (2021).
[2] J. Sun, E. Timurdogan, A. Yaacobi, et al, Large-scale nanophotonic phased array, Nature 493, 195-199 (2013).
[3] C.V. Poulton, A. Yaacobi, D.B. Cole, M.J. Byrd, M. Raval, D. Vermeulen, M.R. Watts, Coherent solid-state LiDAR with silicon photonic optical phased arrays, Opt. Lett. 42, 4091-4094 (2017).
[4] X. Luo, Engineering Optics 2.0, a Revolution in Optical Theories, Materials, Devices and Systems, (Springer), 14 (2019).
[5] W. Li, X. Zhao, et al, High-speed 2D beam steering based on a thin-film lithium niobate optical phased array with a large field of view, Photon. Res. 11, 1912-1918 (2023).
[6] Z. Wang, X. Li, et al, Fast-speed and low-power-consumption optical phased array based on lithium niobate waveguides, Nanophotonics, vol. 13, n. 13, (2024).
