HHG, Attosecond pulse generation and the Mid-IR generation

These are three themes but they are closely connected. One way to generate attosecond pulses is HHG. To generate broadband, a longer wavelength is desired, which has driven the research of Mid-IR generation. Of course Mid-IR generation has many other applications as well. For example, in Oliver Chalus’s talk, he mentioned that Mid-IR laser can be used for cancer diagnostics. He presented their generation of 6 cycle pulses (67 fs at 3.1 µm) with compressed energy of 3.8 µJ. He mentioned they just pushed the energy higher to 5.7 µJ. By combining fiber lasers with OPCPA technology they realized hands off, stable operation with the source passively CEP stabilized through DFG (difference frequency generation).

Ming-Chang Chen at JILA reported their generation of bright coherent attosecond soft X-Ray harmonics spanning the water window from a tabletop source---3.7 µm. When 2 µm pump laser is used, the harmonics extended to 520 eV. Now they are using 3.55 µm driving lasers for HHG generation, collaboration with Andrius Baltuška at Vienna U. of Technology.

Maximilian reported widely tunable infrared pulse generation with novel OPA which pushes the Mid-IR generation wavelength to 4.4 µm, limited by the nonlinear crystal transmission.