Macroscopic manipulation of high-order-harmonic generation through bound-state coherent control

Area of Science:

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

Background:

• High-order harmonic generation (HHG) is a crucial process for producing coherent light in the UV-visible spectrum.
• Controlling HHG at a macroscopic level is essential for practical applications but remains challenging.
• Quasi-phase-matching (QPM) is a key technique for enhancing HHG efficiency, typically achieved spatially.

Purpose of the Study:

• To propose and demonstrate a novel paradigm for macroscopic control of high-order harmonic generation.
• To explore the modulation of bound-state atomic populations for controlling HHG.
• To investigate the feasibility of both spatial and temporal quasi-phase-matching in HHG.

Main Methods:

• Simulations of a scaled high-order harmonic generation process.
• Utilizing a 2.6 μm far-off-resonance source to generate UV-visible harmonics from alkali-metal-atom vapor.
• Employing a resonant near-infrared source for coherent control of atomic populations via Rabi oscillations and rapid adiabatic passage.

Main Results:

• Demonstrated macroscopic control of HHG by modulating the bound-state population of medium atoms.
• Achieved purely temporal quasi-phase-matching (QPM) by inducing homogeneous Rabi oscillations.
• Established spatial QPM by creating a population inversion grating using rapid adiabatic passage.

Conclusions:

• The proposed paradigm offers a new pathway for macroscopic control of high-order harmonic generation.
• The ability to establish both spatial and temporal QPM opens up advanced possibilities for light manipulation.
• This work provides a foundation for developing novel coherent light sources and quantum control techniques.