Effect of stacking configuration on high harmonic generation from bilayer hexagonal boron nitride

Area of Science:

• Condensed Matter Physics
• Quantum Optics
• Materials Science

Background:

• High harmonic generation (HHG) is a key process for producing extreme ultraviolet and X-ray radiation.
• Bilayer hexagonal boron nitride (h-BN) offers unique electronic properties due to its layered structure and stacking configurations.

Purpose of the Study:

• To theoretically investigate high harmonic generation in bilayer h-BN with different stacking orders.
• To understand the influence of stacking configuration on HHG efficiency and spectral characteristics.
• To explore the potential for controlling and utilizing enhanced harmonics for attosecond pulse generation.

Main Methods:

• Solving the extended multiband semiconductor Bloch equations.
• Simulating HHG in bilayer h-BN under strong laser fields.
• Analyzing electron dynamics and transition probabilities based on stacking symmetry.

Main Results:

• AA andomIndex'-stacking bilayer h-BN shows a one-order-of-magnitude higher harmonic intensity than AA-stacking in the high-energy region.
• Broken mirror symmetry in AA andomIndex'-stacking facilitates inter-layer electron transitions, enhancing harmonic efficiency.
• Harmonic emission is tunable via control of the carrier envelope phase of the driving laser.

Conclusions:

• The stacking configuration of bilayer h-BN critically affects high harmonic generation efficiency.
• Additional transition channels in AA andomIndex'-stacking are responsible for the observed enhancement in harmonic emission.
• Controlled HHG in bilayer h-BN can lead to the generation of single intense attosecond pulses.