This effect occurs when a light pulse travels through a material with an extremely steep change in refractive index over a narrow frequency range. While the phase velocity of the individual waves remains high, the overall envelope of the pulse slows down to a fraction of the speed of light in a vacuum. Researchers use ultracold atomic gases or specialized photonic structures to delay optical signals, which helps build optical buffers and quantum memory systems.
Heard on the job
We need to tune the probe laser exactly to the resonance to get the slow light delay we want for the optical buffer.
Insider tip
True slow light reduces the group velocity of a pulse without destroying its shape, unlike simple absorption or severe distortion.