Electromagnetic “Bubbles” and Shock Waves: Unipolar, Nonoscillating EM Solitons

We show that atomic gases can support solitary pulses of a unipolar electromagnetic field (“EM bubbles”) with amplitude up to the atomic field ( $\sim$1$0^9$ V/cm) and duration down to $\sim$ ${10}^{-16\mathrm{}}$ s. EM bubbles propagate without dispersion, are stable, and are insensitive to the change of gas density. Atomic gasses can also support an EM shock wave forming a precursor of a dc ionizing field.