Detecting light and radiation is essential across the electromagnetic spectrum, but some regions remain especially challenging. One of those is the terahertz (THz) range, which sits between microwaves and infrared light. Existing detectors for these frequencies are often slow, lack sensitivity, or depend on large, costly equipment that frequently requires cryogenic cooling.
Researchers have now developed a compact new detector that combines quantum physics with a specially engineered metasurface to significantly improve the way terahertz radiation is captured and converted into electrical signals. Their findings were recently published in Advanced Photonics.
The new device relies on a phenomenon known as the in-plane photoelectric effect. In this process, incoming terahertz photons transfer energy to electrons confined within a two-dimensional electron gas. Those energized electrons cross a carefully designed potential step, producing an electrical current that can be measured.
Unlike conventional photoelectric detectors, this mechanism does not require photons to exceed a minimum energy threshold. Because the process occurs entirely within the plane of the material, it also avoids several efficiency limitations that have constrained earlier detector designs.
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