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Strong ultrafast nonlinear optical response from megaelectronvolt electrons in semiconductors.
D Jeong1, T R Hopper2,3, Y Kim1
1Department of Radiology, Stanford University, Stanford, CA USA.
Nature Photonics
|June 8, 2026
Summary
Scientists observed a strong nonlinear optical response in semiconductors when hit by MeV electrons. This allows for precise, room-temperature detection of ionizing radiation using common materials and lasers.
Area of Science:
- Physics
- Materials Science
- Optics
Background:
- Understanding ultrafast radiation-matter interactions is crucial for advanced detection technologies.
- Detecting highly ionizing radiation is difficult due to dispersed energy deposition.
Purpose of the Study:
- To investigate the nonlinear optical response in semiconductors induced by MeV electrons.
- To explore a new method for precise spatiotemporal detection of ionizing radiation.
Main Methods:
- Irradiation of semiconductors with 150-fs, 4.2-MeV electrons.
- Measurement of sub-10-ps optical modulation and absorption edge shifts.
- Calculation of carrier densities and spatial localization.
Main Results:
- Observed up to 24.5% optical modulation with a sub-10-ps response time.
- Achieved carrier densities of 10^18 cm^-3, 100-fold higher than expected.
- Demonstrated extreme spatial localization of carriers along ionization trajectories.
Conclusions:
- The strong nonlinearity enables precise spatiotemporal detection of ionizing radiation.
- This method works at room temperature using common semiconductors and laser systems.
- Potential applications in radiation detection, plasma monitoring, and medical imaging.
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