Abstract
The authors report the measurement of the angularly resolved spectrum of the third harmonic generated in a femtosecond filament in air and its evolution with increasing pump power. Pumped by a focused infrared ultrashort pulse with a carrier wavelength of 1270 nm, a pulse duration of ∼20 fs, and pulse energy up to 487 μJ, the generated third harmonic is composed of an on-axis emission and a conical ring emission. When the pump power is sufficiently high, angularly resolved spectra with significant X-like feature could be observed, indicating the formation of nonlinear X wave at third harmonic.
| Original language | English |
|---|---|
| Article number | 011111 |
| Journal | Applied Physics Letters |
| Volume | 92 |
| Issue number | 1 |
| DOIs | |
| State | Published - 2008 |
| Externally published | Yes |