An electrically pumped surface-emitting semiconductor green laser

Area of Science:

• Optoelectronics
• Materials Science
• Nanotechnology

Background:

• Surface-emitting semiconductor lasers are crucial for data communications, sensing, and augmented reality.
• Conventional lasers often rely on distributed Bragg reflectors (DBRs), which present fabrication challenges, especially for specific wavelengths.
• Developing efficient, low-threshold lasers in the visible spectrum remains an active area of research.

Purpose of the Study:

• To demonstrate the first all-epitaxial, distributed Bragg reflector (DBR)-free electrically injected surface-emitting green laser.
• To utilize photonic band edge modes in gallium nitride (GaN) nanocrystal arrays as an alternative to DBRs.
• To achieve a low threshold current density for visible spectrum laser diodes.

Main Methods:

• Fabrication of dislocation-free gallium nitride (GaN) nanocrystal arrays.
• Exploitation of photonic band edge modes within the GaN nanocrystal structure.
• Electrical injection to achieve laser emission at ~523 nm.

Main Results:

• Successful demonstration of an electrically injected, DBR-free surface-emitting green laser.
• Operation wavelength achieved at approximately 523 nm.
• A threshold current density of ~400 A/cm² was recorded, significantly lower than previous blue laser diodes.

Conclusions:

• This work presents a new approach for developing surface-emitting laser diodes across the ultraviolet to deep visible spectrum (200-600 nm).
• The use of GaN nanocrystal arrays and photonic band edge modes overcomes limitations associated with DBRs, lattice mismatch, and substrate availability.
• This advancement paves the way for next-generation optoelectronic devices with improved performance and broader spectral coverage.