On-the-Fly Control of High-Harmonic Generation Using a Structured Pump Beam

Area of Science:

• Atomic, Molecular, and Optical Physics
• Nonlinear Optics
• Quantum Optics

Background:

• High harmonic generation (HHG) is a crucial process for producing extreme ultraviolet (XUV) and soft X-ray radiation.
• Efficient HHG typically requires precise phase-matching conditions, which are challenging to maintain, especially at higher gas pressures.

Purpose of the Study:

• To demonstrate a novel, simple, and all-optical technique for enhancing and controlling high harmonic generation.
• To achieve tunable quasi-phase matching (QPM) using interfering spatial optical modes in the pump beam.

Main Methods:

• Utilized two interfering spatial optical modes as the pump beam for high harmonic generation.
• Implemented a tunable periodic quasi-phase matching scheme by controlling the interference pattern of the pump modes.
• Experimentally validated the technique at ambient gas pressures of 50 and 100 Torr.

Main Results:

• Achieved on-the-fly quasi-phase matching for high harmonic orders ranging from 29 to 41.
• Observed a significant enhancement of up to 100-fold in the high harmonic emission intensity.
• Demonstrated the scalability of the technique to different harmonic orders and gas pressure conditions.

Conclusions:

• The proposed all-optical technique offers a powerful and straightforward method for enhancing and controlling HHG.
• Tunable QPM via interfering optical modes provides an effective solution for efficient HHG at higher pressures.
• This method holds promise for various applications requiring tunable XUV/soft X-ray sources.