Integrated Electro-optics on Thin-film Lithium Niobate

By Samudrapom DamReviewed by Louis CastelAug 8 2025

A paper recently published in the journal Nature Reviews Physics reviewed emerging applications of thin-film lithium niobate (TFLN) electro-optics.

An Overview

Electro-optics bridges electronics and photonics, forming the basis for diverse applications in sensing, computing, communications, and quantum information. Integrated electro-optic systems enable high-speed electronic control of photonic signals, while also taking advantage of photonics’ natural ability to process information in parallel with electronics. TFLN has become a strong platform for electro-optics, offering a combination of high electro-optic coupling, wide microwave bandwidth, and exceptionally low optical loss. Its tight optical field confinement and compatibility with advanced nanofabrication make it scalable and reconfigurable, enabling device functionalities that were not possible with bulk systems.  

These capabilities have led to the creation of novel electro-optic devices that not only outperform the current state of the art but also introduce entirely new functionalities. TFLN also opens the door to exploring advanced physical concepts such as photonic non-Hermitian synthetic dimensions, quantum electro-optics, and active topological photonics. With recent advancements, the field is evolving from a focus on individual components to fully integrated system-on-a-chip solutions. While conventional applications remain important, like in telecom and microwave photonics, emerging applications are now gaining more attention.

Nonlinear Photonics

TFLN exhibits excellent second-order (χ⁽²⁾) and third-order (χ⁽³⁾) nonlinearities, enabling parametric frequency-conversion processes combined with electro-optics. This combination creates opportunities for exploring fundamental physics, developing novel devices, and practical applications. The coexistence of electro-optic effects and the Kerr effect in TFLN introduces additional degrees of freedom for synthetic electro-optic lattices, allowing simulation of strongly correlated condensed matter models beyond traditional approximations. On the application side, integrated nonlinear frequency combs enable technologies such as tunable optical parametric oscillators, ultra-stable millimeter- and microwave-wave generation, astrocombs, and precision ranging. TFLN’s multiple strong nonlinearities could further enhance these capabilities.

At the device level, TFLN enables novel comb generation approaches like electro-optic-Kerr combs in the same resonator and cascaded electro-optic modulators with Kerr resonators. System-level integration with comb sources, modulators, and periodically poled lithium niobate waveguides can further benefit these applications. Additionally, integrating gain technologies like reflective semiconductor optical amplifiers and ion-embedding methods like erbium- and thulium-doping offers exciting prospects for lasers at exotic wavelengths and ultrafast pulse generation, potentially advancing atomic physics, supercontinuum generation, and biomedical imaging.

Active Topological Photonics and Non-Hermitian Physics

Microwave-coupled optical lattices on TFLN offer a promising platform for exploring non-Hermitian physics, topological photonics, and high-speed, sensitive microcavity sensing. The strong inherent piezoelectric interaction in TFLN enables electro-optic modulation to add new control degrees of freedom to acoustic sensors and supports practical implementations of modulation-induced gauge fields for photons. These advancements highlight TFLN’s unique capability for ultrafast tuning in optical systems, making it suitable for studying optical physics and innovating light manipulation using waveguides and cavities.

Quantum Photonics

TFLN will play a key part in quantum photonics due to its favorable properties. Light’s high carrier frequency allows for high-bandwidth quantum communication and precise quantum state measurements of individual photons, since these energies exceed thermal background noise. TFLN’s low optical loss, potential for large-scale integration, and capability for photon-photon interactions via electro-optic effects and χ⁽²⁾ nonlinearities make it an excellent platform for manipulating and generating quantum states of light.

Although efficient single-photon nonlinearities remain a challenge in TFLN, the material supports beam splitting and high-bandwidth electro-optic phase shifting, which are essential for linear-optical quantum computing. Additionally, frequency-domain quantum computing protocols benefit from TFLN’s combs and modulators, leveraging light’s multiplexing capacity. Coupled ring resonators can perform frequency-domain beam splitting using only a single phase modulator without expanding the Hilbert space. High-bandwidth switching also enables inefficient spatially multiplexed heralded state conversion into quasi-deterministic ones, useful for photon sources and quantum communications.

The all-optical χ⁽²⁾ interactions, achieved through periodic TFLN poling, further enhance its electro-optic platform. These interactions facilitate the generation of photon pairs and deterministic wavelength conversion of photons, which are important for photonic quantum computing, quantum interconnects between devices at different energies, up-conversion detection, and quantum sensing. Cascaded χ⁽²⁾ processes allow for efficient frequency comb generation.

Beyond electro-optic effects and χ⁽²⁾ interactions, TFLN’s strong piezoelectric coupling enables quantum interconnects between acoustic phonons and microwave photons, useful for transduction and acoustic modulation. Moreover, TFLN’s embedded rare earth ions offer promising quantum emitters, storage, and signal manipulation capabilities.

Photonic Computing and Accelerators

Tightly integrated, power-efficient electronic-photonic systems are propelling progress in optical communication, computing, and microwave photonics. TFLN is emerging as a key enabler of these breakthroughs, especially in the context of artificial intelligence and deep neural networks, where traditional central processing units and graphics processing units face memory and speed bottlenecks. The photonics community has responded with architectures aimed at accelerating artificial intelligence training and inference, including frequency-comb-based processors and optical attenuators.

TFLN offers significant advantages in speed and power consumption. Heterogeneous integration of lasers on TFLN enables high-power data channels, while electro-optic and Kerr frequency combs provide massive parallelism through frequency-division multiplexing. High-speed electro-optic modulators operating at complementary metal-oxide semiconductor-compatible voltages offer exceptional computational power and reconfigurability.

Additionally, TFLN’s native χ⁽²⁾ nonlinearity and integration with high-speed III-V photodiodes open opportunities for on-chip nonlinear activation and opto-electronic conversion, enabling fully optical computation. As the TFLN platform matures, it may support monolithic photonic neural networks that rival/surpass conventional electronic systems.

To summarize, TFLN is revolutionizing electro-optics by enabling scalable, high-speed, low-power photonic systems across communications, quantum technologies, sensing, and optical computing applications.

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