Coherent subterahertz radiation from femtosecond infrared filaments in air.
We report on what is believed to be the first observation of coherent subterahertz (sub-THz) emission from a 1-m string in the atmosphere. The sub-THz pulse emitted by the filamentary structure from an intense IR femtosecond laser pulse is detected perpendicularly to the laser propagation axis by use of two heterodyne detectors at 94+/-1 and 118+/-1GHz . We describe the characteristics of this emission and show evidence of constructive interference between two separate strings.
Tzortzakis
S
S
Méchain
G
G
Patalano
G
G
André
Y-B
YB
Prade
B
B
Franco
M
M
Mysyrowicz
A
A
Munier
J-M
JM
Gheudin
M
M
Beaudin
G
G
Encrenaz
P
P