Engineers at Duke University have developed an ultrathin photodetector capable of capturing light across the entire electromagnetic spectrum in just 125 picoseconds, making it one of the fastest devices of its kind. This innovative pyroelectric sensor detects light by measuring the heat generated when light is absorbed.

Operating at room temperature without the need for external power, the device can be seamlessly integrated into on-chip systems. Its unique capabilities pave the way for advanced multispectral imaging technologies with potential applications in areas such as skin cancer detection, food safety monitoring, and large-scale agricultural analysis.

The research findings were published in Advanced Functional Materials.

Figure 1. Conceptual Image of Plasmonic Light Capture in a Metasurface

Limitations of Conventional Light Detection

Most modern digital cameras rely on semiconductor-based photodetectors that convert visible light into electrical signals, which are then processed to form images. However, these detectors are limited to a narrow portion of the electromagnetic spectrum, much like human vision. Figure 1 shows Conceptual Image of Plasmonic Light Capture in a Metasurface.

To detect a wider range of wavelengths, researchers use pyroelectric detectors that generate electrical signals from heat produced when light is absorbed. Despite their broader spectral capability, these thermal detectors have traditionally been less efficient. They often require either thick absorbing materials or very intense light to produce sufficient heat, making them bulky and slow in response.

As explained by Maiken Mikkelsen, conventional pyroelectric detectors lack sensitivity, which limits their speed. By combining near-perfect light absorbers with ultrathin pyroelectric materials, her team achieved a dramatically faster response time of 125 picoseconds—marking a significant advancement in photodetection technology.

Metasurface Engineering for Efficient Light Trapping

The researchers developed their approach using a metasurface—a precisely engineered structure composed of silver nanocubes arranged on a transparent layer positioned just 10 nanometers above a thin gold film. When light interacts with these nanocubes, it excites electrons in the silver, trapping the light’s energy through plasmonic effects. The wavelengths absorbed can be tuned by adjusting the size and spacing of the nanocubes.

This highly efficient light-trapping mechanism allows the device to function with only an ultrathin layer of pyroelectric material beneath the surface to generate an electrical signal. Although the team first demonstrated this concept in 2019, its response speed was not evaluated at that time.

Maiken Mikkelsen noted that thermal photodetectors have long been considered inherently slow, making the results surprising for the scientific community. The team was astonished to observe that their device operated at speeds comparable to conventional silicon photodetectors, challenging established expectations in the field.

Advancements in Faster Device Design and Measurement

In recent years, Eunso Shin, a PhD student in Maiken Mikkelsen’s lab, has advanced the device design while also developing a more affordable method to measure its speed without relying on costly instrumentation.

The improved design replaces the rectangular metasurface with a circular one, enhancing light capture and reducing the distance signals must travel. The team also integrated thinner pyroelectric materials from collaborators and upgraded the circuitry for more efficient signal readout and transmission.

To evaluate performance, Shin devised an experimental setup using two distributed feedback lasers. As their frequencies approached the detector’s operating range, the signal intensified, enabling precise measurement of the device’s response time. The results revealed that the photodetector can operate at speeds up to 2.8 GHz, corresponding to an ultrafast response time of just 125 picoseconds.

Shin noted that typical pyroelectric photodetectors function in the nano- to microsecond range, making this device hundreds to thousands of times faster. While the results mark a significant breakthrough, ongoing work aims to further increase speed and better understand the fundamental limits of pyroelectric photodetection.

Future Prospects in Imaging and Sensing Technologies

The researchers suggest that performance could be further enhanced by embedding the pyroelectric material and readout electronics within the narrow gap between the nanocubes and the gold layer. They are also investigating multi-metasurface designs capable of simultaneously detecting multiple light wavelengths and their polarization.

As the technology matures and fabrication challenges are resolved, it has the potential to enable advanced imaging systems [1]. Since these detectors operate without external power, they are particularly suitable for deployment in drones, satellites, and spacecraft.

Such capabilities could significantly benefit precision agriculture by enabling real-time monitoring of crop conditions, such as water and nutrient needs. According to Maiken Mikkelsen, the ability to detect multiple frequencies at once could unlock a wide range of future applications, including cancer diagnostics, food safety analysis, and remote sensing—though these applications are still in the early stages of development.

References:

1. https://scitechdaily.com/duke-engineers-trap-light-to-create-the-fastest-photodetector-ever-built/

Cite this article:

Janani R (2026), Duke Engineers Capture Light to Build the Fastest Photodetector Ever, AnaTechMaz, pp. 373