Duke Engineers Shatter Speed Records With Photodetector That Responds in 125 Picoseconds

Engineers at Duke University have shattered the performance limits of an entire class of light detectors by trapping light inside precisely engineered silver nanocubes, producing a device that can sense radiation across the full electromagnetic spectrum — from X-rays through visible light to the terahertz radio band — and generate a usable electrical signal in just 125 picoseconds, hundreds to thousands of times faster than any comparable thermal detector previously built.

Conventional pyroelectric photodetectors — devices that produce electricity when their temperature changes in response to incoming light — typically operate in the nano-to-microsecond range, a speed limitation rooted in the physics of heat flow through bulk materials. Professor Maiken Mikkelsen and PhD student Eunso Shin at Duke's Pratt School of Engineering solved this fundamental constraint by engineering a 'metasurface' — a precisely structured array of metallic nanoparticles — that concentrates incoming light's energy almost instantaneously onto an ultrathin pyroelectric layer, eliminating the thermal mass that normally slows the device's response to a crawl.

The key to the breakthrough is geometric and plasmonic. Silver nanocubes just tens of nanometers across are arranged with exacting precision on a transparent polymer film only 10 nanometers above a thin layer of gold. When a photon strikes a nanocube, it excites the collective oscillation of the metal's conduction electrons — a phenomenon known as localized surface plasmon resonance — effectively trapping the photon's energy at the metal-dielectric interface. Because the energy is deposited in a layer thinner than a few dozen nanometers, the resulting temperature pulse propagates through the pyroelectric material in picoseconds rather than nanoseconds. By tuning the size and spacing of the nanocubes, engineers can also specify exactly which wavelengths are most efficiently absorbed, enabling programmable spectral sensitivity.

The device operates at speeds up to 2.8 GHz — placing it firmly in the radio-frequency electronic range — and requires no external power source or cryogenic cooling, a decisive practical advantage over competing ultrafast detectors such as superconducting nanowire single-photon detectors, which must be maintained at temperatures near absolute zero. The ultrathin architecture is also fully compatible with standard semiconductor fabrication processes, meaning commercial scale-up would not require entirely new manufacturing infrastructure. The research was published in Advanced Functional Materials in late 2025 and was formally highlighted by the Duke Pratt School of Engineering in March 2026.

The applications motivating the research are broad and urgent. Multispectral cameras that can simultaneously image across the visible and infrared bands are currently assembled from multiple different sensor types, adding weight, complexity, and cost. A single broadband detector with gigahertz speed could enable dermatologists to scan for skin cancer signatures without biopsy, food safety inspectors to detect contamination across a wide spectral range, agricultural satellites to monitor crop stress from orbit, and next-generation free-space optical communication links to relay data at speeds unachievable with current detector technology. The team is actively working with industry partners on commercialization pathways and investigating whether the plasmonic design principle can be extended to organic and flexible substrates for conformal sensor applications.