Quasi-BIC laser enabled by high-contrast grating resonator for gas detection

Area of Science:

• Photonics
• Nanotechnology
• Sensing Technology

Background:

• Bound states in the continuum (BIC) offer high-Q resonances crucial for laser development.
• Microlasers are essential for compact photonic integrated circuits.
• Gas sensing requires sensitive and selective detection methods.

Purpose of the Study:

• To propose and numerically investigate a 2D microlaser utilizing BIC.
• To demonstrate ultra-low threshold lasing in the visible range.
• To evaluate the device's potential for on-chip gas sensing.

Main Methods:

• Numerical investigation of a 2D microlaser structure composed of a dye-doped gain layer and high-contrast gratings.
• Exploitation of quasi-BIC modes by partially breaking a BIC at the Γ point.
• Optical pumping of the gain medium to achieve lasing.

Main Results:

• Achieved ultra-low pump threshold (17 μJ/cm²) and narrow optical linewidth.
• Demonstrated sensitive detection of environmental refractive index changes (5 × 10⁻⁴).
• Obtained a bulk sensitivity of 221 nm/RIU and a figure of merit of 4420 RIU⁻¹.

Conclusions:

• The developed quasi-BIC microlaser enables efficient, low-threshold lasing.
• The device exhibits excellent sensing performance for gas detection.
• This ultracompact BIC laser is a promising candidate for on-chip gas sensors.