Relativistic plasmas open a route to extreme optical fields

Nature, Published online: 06 May 2026; doi:10.1038/d41586-026-01311-3

By precisely shaping the leading edge of ultrafast high-power laser pulses, bright ‘harmonic’ radiation has been generated with great efficiency from plasma oscillating at almost the speed of light. This long-sought regime removes a key barrier to the production of extremely intense electromagnetic fields for applications such as compact particle acceleration, attosecond science and strong-field physics.