Science Alert July 15, 2023
Scientists experimenting with some of the most fundamental laws of physics have found more evidence of photonic time crystals (PTCs): materials in which the refractive index oscillates very quickly. An international team of researchers (Israel, USA – University of Perdue) trained lasers on two transparent conducting oxides and used the lasers to rapidly change the refractive index for periods less than 10 femtoseconds. They observed significant shifts in the light frequency and in the light relaxation time depending on the thickness of the material and the speed with which the refractive index was altered. Increasing the refractive index abruptly led to time-refraction where the spectrum of all the waves propagating in the medium was red-shifted, and subsequently blue-shifted when the refractive index relaxed back to its original value. They observed these phenomena in the single-cycle regime, so far, these types of PTCs have only been observed using radio waves, which have much lower frequencies than light waves How it exactly happens has yet been understood… read more. Open Access TECHNICAL ARTICLEÂ
Experimental setup for measuring time-refraction in the single-cycle regime… Credit: Nanophotonics, vol. 12, no. 12, 2023, pp. 2221-2230.Â