Nanoscale Device Electrically Controls Light Intensity

Abstract

Nonlinear intersubband polaritonic metasurfaces based on coupling of the intersubband nonlinear optical response of quantum-engineered semiconductor heterostructures and electromagnetic modes of nanoresonators provide efficient frequency mixing with moderate pump intensities. The resonant nonlinear optical response, represented as a complex function, can be modulated via Stark tuning of intersubband transition energies under applied voltages. However, achieving full complex amplitude control (both phase and magnitude) remains challenging. In this work, we present and experimentally validate electrically tunable nonlinear intersubband polaritonic metasurfaces that achieve complete complex amplitude control for second-harmonic generation (SHG). Through a design featuring two in-plane flipped meta-atoms per unit cell, we achieve complete electrical control of both the amplitude and phase of the metasurface second-order nonlinear susceptibility, with a tuning range of 0 to 30 nm V−1 for the magnitude and 0-2π for the phase of the nonlinear optical response. Using these properties, we achieve complete on-off SHG modulation and beam diffraction tuning through electrically controlled amplitude and phase gratings.

A groundbreaking nanoscale optical device has been developed that allows independent control over the intensity and phase of light. By applying voltage, this innovative device can freely manipulate the phase and magnitude of second-harmonic (SH) light, opening new avenues for advanced quantum communication and information processing technologies.

Professor Jongwon Lee and his research team in the Department of Electrical Engineering at UNIST announced the creation of an electrically operated nano-optical component capable of complete, independent modulation of the phase and intensity of SH light. This device represents a significant advancement in nonlinear optics, a field that involves altering light properties through interactions with specialized materials-a fundamental process in generating entangled photon sources and other quantum optical systems.

The nano-optical device is remarkably small-only about one ten-thousandth the size of a fingernail-enabling it to replace bulkier materials and paving the way for lighter, more compact optical systems. Unlike conventional nano-optic components that operate passively, this device can be actively controlled via applied voltage, allowing for the precise adjustment of both phase and amplitude. Such control enables the encoding of more complex information, which is critical for next-generation quantum technologies.

Experimental results demonstrated nearly 100% modulation depth of the SH signal intensity, with the phase tunable over the full 0 to 360-degree range. Additionally, the nonlinear response could be adjusted within a range of approximately 0 to 30 nm/V, indicating that the device can achieve complete electrical control over the complex amplitude in both magnitude and phase space.

Leveraging this technology, the team successfully demonstrated the creation of phase and amplitude gratings, enabling dynamic control of diffraction patterns of the output light. These capabilities have promising applications in real-time wavefront shaping, high-speed data encoding, and contactless optical switching.

Figure 1. Conceptual illustration of complex-amplitude-controllable nonlinear polaritonic metasurface.

The key to this breakthrough lies in the device's surface design, which incorporates nanostructures combining quantum wells and metal nanocavities arranged in pairs with opposite phases (180° difference). This precise engineering allows for highly efficient and independent tuning of nonlinear optical responses.

Professor Lee commented,"We have, for the first time, surpassed the physical limitations of existing nonlinear optical devices by introducing a miniaturized platform that achieves high-speed, high-precision optical control solely through electrical signals." He further added, "This technology has the potential to serve as a foundational platform for active quantum optics systems, such as entangled photon sources and quantum interference control."

This research has been published in Science Advances on July 25, 2025, supported by the Institute for Information & Communications Technology Planning & Evaluation (IITP) and the National Research Foundation of Korea (NRF).

Journal Reference

Jaeyeon Yu, Jaesung Kim, Hyeongju Chung, et al., "Full complex amplitude control of second-harmonic generation via electrically tunable intersubband polaritonic metasurfaces," Sci., Adv., (2025).