A Review on the Gallium Nitride Laser

Abstract

One kind of semiconductor laser is the gallium nitride laser. Gallium nitride-based semiconductor lasers are a typical kind of blue laser; they emit wavelengths that fall between 360 and 480 nm, and the human eye interprets these wavelengths as blue or violet. Gallium nitride (GaN) is thought to be the best gain medium for semiconductor lasers. [22]

Introduction

A laser is a device that emits light through optical amplification based on stimulated emission of electromagnetic radiation. The term "laser" stands for light amplification by stimulated emission of radiation. The first laser was built by Theodore Maiman in 1960, inspired by theoretical work from Charles Townes and Arthur Schawlow. Lasers emit coherent light, which allows them to be focused into small areas (spatial coherence) and maintain narrow beams over long distances (collimation). They can also produce narrow frequency spectra (temporal coherence) or ultrashort pulses.

Applications of lasers include cutting and welding, printing, scanning, DNA sequencing, communications, photolithography, surgery, entertainment, military targeting, and automotive lighting. Lasers operate at optical frequencies, while masers operate at microwave frequencies. The verb "to lase" refers to producing coherent light.

History and development:

• Einstein (1916) predicted stimulated emission.

• Rudolf Ladenburg (1928) first observed it experimentally.

• Townes (1951–1953) developed the maser at microwave frequencies.

• Townes and Schawlow (1958) proposed the optical maser concept; Gordon Gould coined the term “laser” and secured patents.

• Maiman (1960) created the first functioning ruby laser.

• The first gas laser (He-Ne) and semiconductor lasers followed soon after.

Laser operation principle:

• Based on quantum energy levels of atoms. Atoms absorb energy, become excited, and release photons when returning to lower energy states.

• Stimulated emission occurs when an incoming photon triggers an excited atom to emit a photon with identical phase, direction, and wavelength.

• Population inversion (more atoms in higher-energy states than lower ones) is required to sustain laser action, achieved via optical or electrical pumping.

• Three-level lasers (e.g., ruby) produce pulses; four-level lasers can emit continuous beams.

Laser components and characteristics:

• Gain medium: solid, liquid, or gas.

• Resonator: mirrors reflect light back and forth to amplify it.

• Laser light is monochromatic, coherent, and collimated.

• Divergence depends on wavelength and aperture; semiconductor lasers often require optics to reduce beam spread.

• Coherence length measures the uniformity of light waves; critical for applications like holography.

• Lasers can emit continuous or pulsed beams, with peak powers in labs reaching over 101510^{15}1015 W and pulse durations as short as femtoseconds.

Gallium nitride (GaN) lasers:

• Emit blue or violet light (360–480 nm).

• Used in high-definition Blu-ray discs due to efficient semiconductor emission without frequency doubling.

Conclusion

One kind of semiconductor laser is the gallium nitride laser. Gallium nitride-based semiconductor lasers are a typical kind of blue laser; they emit wavelengths that fall between 360 and 480 nm, and the human eye interprets these wavelengths as blue or violet. Gallium nitride (GaN) is thought to be the best gain medium for semiconductor lasers.[22]

References

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Copyright

Copyright © 2025 Muhammad Arif Bin Jalil. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.