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Description
We present a scheme to suppress Amplified Spontaneous Emission (ASE) in a high-gain Fe:ZnSe chirped pulse amplifier (CPA) by increasing the seed energy from sub-µJ to sub-mJ level. The high-energy seed pulses are generated using a broadband optical parametric chirped pulse amplifier based on ZnGeP2 (ZGP) pumped by a Ho:YLF CPA.
Shifting the driving wavelength in ultra-fast physics, e.g. High Harmonic Generation (HHG) to the mid-infrared (MIR) brings various benefits and will be a vital step to elevate experiments to the next level. While HHG driven by Ti:Sapphire lasers can reach cutoff energies of up to 130 eV, HHG driven by a 4 µm laser could reach energies above 1 keV. This would enable attosecond transient absorption spectroscopy experiments on vital elements such as 3d transition metals, Fe, Co, and Ni.
An essential step for this is generation of short, high-energetic laser pulses in the MIR. Fe:ZnSe is a promising candidate to become the workhorse of MIR pulsed lasers. It has many similarities to Ti:Sapphire, including a broadband emission bandwidth. In the past, we showed a Fe:ZnSe CPA capable of delivering up to 4.33 mJ. The total energy of this system was limited by ASE.
By preamplifying the seed using a ZGP OPCPA, we can reduce the ASE in the amplifier. The OPCPA can increase the energy from sub µJ to >100 µJ with very low optical parametric generation It will lead to significantly reduced ASE in the Fe:ZnSe CPA, which will enable a further increase of its output energy- and will allow the addition of a second amplification stage.
| Keyword-1 | Mid-Infrared |
|---|---|
| Keyword-2 | High Harmonic Generation |
| Keyword-3 | Fe:ZnSe Amplifier |