Highly efficient broadband terahertz generation from ultrashort laser filamentation in liquids
Indranuj Dey, Kamalesh Jana, Vladimir Yu. Fedorov, Anastasios D. Koulouklidis, Angana Mondal, Moniruzzaman Shaikh, Deep Sarkar, Amit D. Lad, Stelios Tzortzakis, Arnaud Couairon, G. Ravindra Kumar
Abstract: Generation and application of energetic, broadband terahertz pulses (bandwidth ~0.1–50 THz) is an active and contemporary area of research. The main thrust is toward the development of efficient sources with minimum complexities—a true table-top setup. In this work, we demonstrate the generation of terahertz radiation via ultrashort pulse induced filamentation in liquids—a counterintuitive observation due to their large absorption coefficient in the terahertz regime. The generated terahertz energy is more than an order of magnitude higher than that obtained from the two-color filamentation of air (the most standard table-top technique). Such high terahertz energies would generate electric fields of the order of MV cm-1, which opens the doors for various nonlinear terahertz spectroscopic applications. The counterintuitive phenomenon has been explained via the solution of nonlinear pulse propagation equation in the liquid medium.