Efficient combination and enhancement of high-power mid-infrared pulses in plasmas

High-power intense optical sources in the mid-to-long wavelength infrared region are very attractive for a wide range of fields from fundamental research to materials science and biology applications. However, there are still significant challenges in extending long-wavelength infrared pulses into the relativistic regime using conventional optical techniques. Here, based upon a new type of plasma-based optical method, we present an efficient scheme capable of combining several high-power long-wavelength infrared laser pulses into one single, more intense pulse, thus bringing the intensity of the output pulse to the relativistic regime. Such intense infrared pulses will open up new possibilities for strong-field physics and ultrafast applications. Furthermore, this is beneficial to understand the underlying physics and nonlinear processes of modulation, propagation and energy transfer of high-power intense laser pulses in plasmas.