Terahertz emission from ultrafast ionizing air in symmetry-broken laser fields.
A transient photocurrent model is developed to explain coherent terahertz emission from air irradiated by a symmetry-broken laser field composed of the fundamental and its second harmonic laser pulses. When the total laser field is asymmetric across individual optical cycles, a nonvanishing electron current surge can arise during optical field ionization of air, emitting a terahertz electromagnetic pulse. Terahertz power scalability is also investigated, and with optical pump energy of tens of millijoules per pulse, peak terahertz field strengths in excess of 150 kV/cm are routinely produced.
Kim
Ki-Yong
KY
Los Alamos National Laboratory, Center for Integrated Nanotechnologies, Los Alamos, NM 87545, USA. kykim@lanl.gov
Glownia
James H
JH
Taylor
Antoinette J
AJ
Rodriguez
George
G