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Room-Temperature Lasing at Flatband Bound States in the Continuum
Thi Thu Ha Do1, Zhiyi Yuan1,2,3, Emek G Durmusoglu4
1Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Singapore 138635, Singapore.
ACS Nano
|May 12, 2025
Summary
Researchers developed flatband bound states in the continuum (BICs) using titanium dioxide nanopillars. This innovation achieves high-quality optical modes for efficient lasers and photonic devices.
Area of Science:
- Photonics and optical engineering
- Materials science
- Condensed matter physics
Background:
- High-quality factor optical modes are crucial for lasers, light-matter interactions, and optical trapping.
- Bound states in the continuum (BICs) offer theoretically infinite quality factors but suffer from practical limitations due to exponential quality factor decay away from singularity.
- Existing symmetry-protected BICs have limitations in practical applications.
Purpose of the Study:
- To present a design concept and experimental realization of flatband BICs.
- To engineer a nondispersive BIC band by controlling guided mode interactions.
- To enhance optical cavity performance for photonic devices.
Main Methods:
- Fabrication of a rectangular array of titanium dioxide nanopillars.
- Engineering the interaction between four counterpropagating guided modes.
- Characterization of the flatband BIC properties and lasing performance.
Main Results:
- Achieved a nondispersive flatband BIC in a rectangular nanopillar array.
- Demonstrated a 2-orders-of-magnitude enhancement in quality factor near the Γ-point compared to symmetry-protected BICs.
- Obtained room-temperature lasing with a quality factor of ~9100 and a 4x lower threshold.
- Observed an exceptionally high optical density of states.
Conclusions:
- The flatband BIC concept offers a significant improvement over traditional BICs.
- This work paves the way for efficient optical cavities, low-threshold microlasers, and advanced photonic devices.
- The demonstrated flatband BICs hold great potential for future optoelectronic applications.
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