Cavity-enhanced high-harmonic generation with spatially tailored driving fields

Area of Science:

• Quantum optics
• Nonlinear optics
• Attosecond science

Background:

• High-harmonic generation (HHG) is crucial for producing extreme-ultraviolet (XUV) light.
• Enhancement cavities improve HHG efficiency but often face limitations in output coupling and power scaling.
• Gaussian beam modes are standard in enhancement cavities, but alternative modes may offer advantages.

Purpose of the Study:

• To investigate high-harmonic generation using a specific transverse cavity mode.
• To compare the performance of this mode against the conventional Gaussian mode in terms of conversion and output coupling efficiency.
• To explore the potential for power scaling and advanced applications like frequency combs and attosecond pulse generation.

Main Methods:

• Theoretical modeling of high-harmonic generation in a 78-MHz enhancement cavity.
• Experimental investigation using a cavity mode with on-axis intensity maxima at the focus.
• Characterization of conversion efficiency and output coupling efficiency.

Main Results:

• The investigated transverse mode yields conversion efficiency comparable to the Gaussian mode.
• Output coupling efficiency is significantly improved compared to existing techniques.
• The approach demonstrates potential for power scaling and flexible control over harmonic emission.

Conclusions:

• A novel cavity mode enhances output coupling efficiency for high-harmonic generation.
• This method provides a pathway to high-power extreme-ultraviolet frequency combs.
• It enables the generation of multi-MHz repetition-rate-isolated attosecond pulses.