GaSb-based mid infrared photonic crystal surface emitting lasers

Area of Science:

• Semiconductor Lasers
• Photonics and Optics
• Mid-Infrared Technology

Background:

• Development of efficient mid-infrared (mid-IR) laser sources is crucial for various applications, including spectroscopy, free-space communications, and medical diagnostics.
• Existing mid-IR laser technologies often face limitations in terms of operating temperature, efficiency, and beam quality.
• Photonic Crystal Surface Emitting Lasers (PCSELs) offer a promising alternative due to their unique surface emission and potential for high power and good beam quality.

Purpose of the Study:

• To demonstrate, for the first time, Gallium Antimonide (GaSb)-based mid-infrared PCSELs capable of operating above room temperature (RT).
• To investigate the performance characteristics of these PCSELs, including lasing wavelength, temperature stability, and threshold power density.
• To explore the effect of photonic crystal (PC) design, specifically air hole depth, on laser performance.

Main Methods:

• Fabrication of GaSb-based PCSELs utilizing Type-I InGaAsSb quantum wells as the active region.
• Construction of a square lattice photonic crystal on the laser surface for optical feedback and surface emission.
• Optical pumping experiments to characterize laser performance at various temperatures.
• Numerical simulations based on coupled-wave theory to analyze the impact of etched depth on laser parameters.

Main Results:

• Successful demonstration of mid-IR PCSELs emitting at ~2.3μm, operating above room temperature up to 350K.
• Observed a temperature-insensitive linewidth of 0.3nm and a low threshold power density of ~0.3KW/cm² at RT.
• Demonstrated a low wavelength shift rate of 0.21 nm/K with increasing temperature.
• Experimental and simulation results showed that increasing the photonic crystal etch depth reduces both lasing wavelength and threshold power.

Conclusions:

• GaSb-based mid-IR PCSELs represent a significant advancement for above-room-temperature operation.
• The demonstrated temperature stability and low threshold power density highlight the potential of these devices for practical applications.
• Photonic crystal design, particularly etch depth, is a critical parameter for optimizing PCSEL performance, offering a pathway for further device improvement.