Study of X-ray generation from mid-infrared laser interaction with nanostructured targets

Regime of relativistic laser-solid interaction with a long wavelength driver is qualitatively different from typically used near-IR and visible laser sources. Novel approach related to the usage of advanced targets together with mid-infrared laser pulses may put a new spin on the development of plasma-based X-ray sources. The first results on the generation of hard X-ray emission within this concept will be presented. In our experiments transparent solid nanostructures of different morphology made of ZnO or Si are illuminated by ultra-intense mid-infrared pulses at 3.9 µm. The measured X-ray spectra dependent on the focusing conditions outline the role of nanowires in terms of “cold” and “hot” line emission generation. Numerical PIC-simulations support the experimental findings and suggest solid density plasma.