Hong Kong University of Science and Technology
Optical Precursors: From Fundamentals to Applications
Optical precursor is a transient electromagnetic wave packet propagating precisely at the speed of light in vacuum through a dispersive and absorptive dielectric. Even though its existence was conjectured by Sommerfeld and Brillouin 100 years ago, the detection was uneasy due to its exceedingly small amplitude and femtosecond timescale duration in ordinary linear dispersive media. In this talk, I present a successful story of the first direct observation of optical precursors using a magneto-optical trap (39K, potassium) and its extension to electromagnetically induced transparency (EIT) media. In addition, the universal features and underlying physics beyond the predictions from modern asymptotic theory are to be explained. By stacking of "resonant" precursors and slow light in an EIT medium, more than 800% of optical burst was achieved with no external gain. Optical precursors will play a significant role as an ultra-precise clock, jitter corrector, and time delay unit in an integrated quantum communication network.