Integrated lithium niobate optical phased array for two-dimensional beam steering

Integrated photonic crystal beam splitters based on thin film lithium niobate

We propose and demonstrate integrated photonic crystal (PhC) beam splitters based on X-cut thin film lithium niobate (TFLN). Its working principle is based on bandgap guidance and total reflection in the PhC slab. We designed two structures: one features a triangular lattice, while the other exhibits a tetragonal lattice. These structures have compact footprint, with size of 14.857×4.982 and 15.275×5.295 µm2 for triangular and tetragonal lattices, respectively. We fabricate these devices by directly etching the TFLN. The measured insertion losses are 3.482 (triangular lattice) and 2.181 (tetragonal lattice) dB. Our proposed PhC beam splitter provides a novel approach for the realization of compact photonic devices on TFLN.

End-fire optical phased array for passive beam steering on thin-film lithium niobate

Autonomous driving technology has put forward higher requirements for sensors, including light detection and ranging. An optical phased array (OPA) is a viable solution, and numerous efforts have been made in this area. For its outstanding optical properties such as linear electro-optic effect and low optical loss, lithium niobate exhibits great potential and unique advantages in solid-state light-emitting arrays. Here we propose and experimentally demonstrate an end-fire optical phased array on a thin-film lithium niobate (TFLN) for passive beam steering. Furthermore, based on this work, we propose a three-line optical phased array to achieve a larger beam steering range. Our results provide a solution for the integrated optical phased array that shows potential in sensing and imaging with reduced size and power.

Optical switch with an ultralow DC drift based on thin-film lithium tantalate

We present an electro-optic (EO) switch with ultralow DC drift on a thin-film lithium tantalate (TFLT) platform, even with SiO2 cladding and without post-annealing processes. The flat Vπ and EO responses have been measured across various driving frequencies, input optical powers, and temperatures. Stable optical switching is achievable in the low-frequency range. The experiment also demonstrated superior long-term stability (up to 2 h) compared to thin-film lithium niobate optical switches under similar on-chip optical power conditions (around -8 dBm).

Fast-speed and low-power-consumption optical phased array based on lithium niobate waveguides

Fast scanning speed and low-power consumption are becoming progressively more and more important in realizing high-performance chiplet optical phased arrays (OPAs). Here, we successfully demonstrated integrated OPAs with multiple waveguides channels based on thin-film lithium niobate-on-insulator (LNOI) platform. Specifically, two lithium niobate (LN) OPA chips have been implemented with 32 and 48 channels LN waveguides, respectively, enabled by electro-optic modulations, which showcases the low power consumption (1.11 nJ/π) and fast operation speed (14.4 ns), showing obvious advantage of the LNOI platform over others. As results, we experimentally achieved a beam steering with a 62.2° × 8.8° field of view (FOV) and a beam divergence of 2.4° × 1.2° for 32 channels, and a FOV of 40° × 8.8° and a beam divergence of 0.33° × 1.8° for 48 channels. This work also demonstrates the feasibility of LNOI platform in scalable OPA chips.

Hybrid integrated thin-film lithium niobate-silicon nitride electro-optical phased array incorporating silicon nitride grating antenna for two-dimensional beam steering

This study proposes a solid-state two-dimensional beam-steering device based on an electro-optical phased array (EOPA) in thin-film lithium niobate (TFLN) and silicon nitride (SiN) hybrid platforms, thereby eliminating the requirement for the direct etching of TFLN. Electro-optic (EO) phase modulator array comprises cascaded multimode interference couplers with an SiN strip-loaded TFLN configuration, which is designed and fabricated via i-line photolithography. Each EO modulator element with an interaction region length of 1.56 cm consumed a minimum power of 3.2 pJ/π under a half-wave voltage of 3.64 V and had an estimated modulation speed of 1.2 GHz. Subsequently, an SiN dispersive antenna with a waveguide grating was tethered to the modulator array to form an EOPA, facilitating the out-of-plane radiation of highly defined near-infrared beams. A prepared EOPA utilized EO phase control and wavelength tuning near 1550 nm to achieve a field-of-view of 22° × 5° in the horizontal and vertical directions. The proposed hybrid integrated platform can potentially facilitate low-power and high-speed beam steering.