Multiple THz pulse generation with variable energy ratio and delay

• Published in: Laser physics letters Vol. 12; no. 4; pp. 45301 - 45306
• Main Authors: Ungureanu, R G, Grigore, O V, Dinca, M P, Cojocaru, G V, Ursescu, D, Dascalu, T
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.04.2015
• Subjects: multiple THz sub-pulses; THz generation; two-color filamentaiton; ultrafast phenomena
• ISSN: 1612-2011; 1612-202X
• DOI: 10.1088/1612-2011/12/4/045301

Two methods for multiple high energetic THz pulse generation by two-color filamentation in air with controllable energy ratio and delay ranging from one to hundreds of ps were investigated. In the first method the laser pulse is split into two inside the optical stretcher of a CPA laser system, the resulting consecutive filaments occur in the same region and allows the study of the influence of the first plasma filament on the THz emission of the delayed filament. Based on a polarization sensitive thin film beam splitter placed in front of a 45° mirror, the second method produces multiple parallel consecutive filaments. Above a certain total pump level the THz energy delivered by multiple pulses exceeds the value given by a single filament for the same pump energy, thereby overcoming the THz emission saturation of the single filament.