Two-Color Mid-Infrared Laser Filaments Produce Terahertz Pulses with Extreme Efficiency

Summary form only given. Despite the rapid development of terahertz (THz) science during the last two decades, the majority of available THz sources remains rather weak, limiting the interactions of THz radiation with matter mostly in the realm of linear optics. Development of powerful THz sources will open the way to many exciting applications spanning from switching and controlling of magnetic domains to THz-enhanced attosecond pulse generation [1,2]. Here we present intense broadband THz emission with extreme efficiency from two-color filamentation of mid infrared laser pulses centered at 3.9 μm originating from an optical parametrical chirped pulse amplifier (OPCPA) system [7]. We demonstrate broadband THz pulses (whose spectra extend up to 16 THz) with energy of 0.185 mJ and THz conversion efficiency of 2.36% (see Fig.la and b), exceeding by far any previous values reported for plasma based THz sources. Our numerical simulations show that the THz yield can be significantly improved by further optimizing the experimental setup. Finally, we show that the generated THz pulses are powerful enough to induce nonlinear cros -phase modulation in electro-optic crystals.