Near-unity spontaneous emission factor InP surface-emitting lasers based on quasi-bound states in the continuum.

Area of Science:

• Optoelectronics
• Materials Science
• Nanotechnology

Background:

• Surface-emitting lasers are crucial for optical technologies.
• Optical bound states in the continuum (BICs) offer enhanced light-matter interaction.
• Top-down fabrication methods for BIC lasers cause structural damage, limiting performance.

Purpose of the Study:

• To overcome fabrication-induced damage in BIC lasers.
• To demonstrate a bottom-up, etching-free approach for surface-emitting quasi-BIC lasers.
• To achieve high-performance, single-mode lasing at room temperature.

Main Methods:

• Epitaxial growth of crystal phase-engineered InP nanosheets.
• Utilizing nanosheets as both laser gain medium and quasi-BIC cavity.
• Leveraging wurtzite crystal structure for mode suppression.

Main Results:

• Demonstrated surface-emitting quasi-BIC lasers via bottom-up fabrication.
• Achieved single-mode lasing at room temperature.
• Reported a low lasing threshold of 14 μJ cm⁻² pulse⁻¹.
• Observed high spontaneous emission factors (up to 0.8) indicating optimal coupling.

Conclusions:

• Bottom-up fabrication successfully avoids structural damage in BIC lasers.
• Quasi-BIC lasers with InP nanosheets show potential for near-thresholdless operation.
• This approach paves the way for high-performance, room-temperature optoelectronic devices.