Ultra-slow-light and dynamically quantitative optical storage modulation via quasi-BICs.

Area of Science:

• Photonics and optical metamaterials
• Condensed matter physics
• Nanotechnology

Background:

• Quasi-bound states in the continuum (quasi-BICs) offer unique light-matter interaction properties.
• Electromagnetically induced transparency (EIT) modes have been explored for slow light applications.
• Graphene's tunable electronic properties present opportunities for dynamic optical control.

Purpose of the Study:

• To implement dynamically tunable dual quasi-BICs in a silicon-graphene multilayer composite.
• To utilize these quasi-BIC modes for achieving ultra-large group delays.
• To investigate the tunability of group delay and its relationship with material properties for advanced optical devices.

Main Methods:

• Fabrication of a silicon-graphene multilayer composite structure.
• Excitation and characterization of dual quasi-BIC modes.
• Analysis of group delay variations with graphene's Fermi level (Ef).
• Theoretical verification of the relationship between group delay and quality factor (Q-factor).

Main Results:

• Achieved dynamically tunable dual quasi-BICs in the silicon-graphene structure.
• Demonstrated ultra-large group delays, 10^5 times slower than light speed, exceeding EIT modes by 2-3 orders of magnitude.
• Showcased dramatic reduction of group delay from 1929.82 ps to 1.58 ps with a 100 meV tuning range of graphene's Fermi level.
• Analyzed the log-linear relationship between group delay and Fermi level, and verified the double-logarithmic relationship between group delay and Q-factor.
• Quantitatively modulated optical storage based on the developed quasi-BIC modes.

Conclusions:

• The silicon-graphene multilayer composite effectively supports tunable dual quasi-BICs for significant group delay enhancement.
• The demonstrated tunability and ultra-large group delays offer a promising platform for next-generation slow light devices and optical information processing.
• This research provides a novel approach for the reform and upgrading of slow optical devices and optical storage technologies.