Square lattice photonic crystal surface mode lasers.

Area of Science:

• Photonics and optical engineering
• Materials science
• Condensed matter physics

Background:

• Photonic crystal microcavities are crucial for controlling light propagation.
• Surface modes in microcavities offer unique light-matter interaction properties.
• Efficient light confinement and low lasing thresholds are key for advanced optical devices.

Purpose of the Study:

• To propose and optimize a square lattice photonic crystal hetero-slab-edge microcavity design.
• To investigate and tune surface modes for enhanced optical properties.
• To explore the potential for low-threshold lasers and sensitive sensor applications.

Main Methods:

• Numerical simulations were employed to investigate and optimize microcavity parameters.
• Tuning of slab-edge termination (τ) and gradual mirror layers was performed.
• Experimental fabrication and characterization were conducted to identify lasing surface modes.

Main Results:

• A high simulated quality (Q) factor of 2.3 × 10^5 and a small mode volume of 0.105 μm^3 were achieved with τ = 0.80.
• Experimental identification of different surface modes lasing was successful.
• A surface mode in the second photonic band gap exhibited a very-low threshold of 140 μW and a Q factor of 5,500.

Conclusions:

• The designed photonic crystal microcavity demonstrates excellent optical performance.
• The observed low threshold and high Q factor of the surface mode are promising for practical applications.
• This work opens avenues for developing efficient low-threshold optical lasers and highly sensitive sensors.