A Review on the Alexandrite Lasers

Abstract

Alexandrite lasers are chromium-doped chrysoberyl lasers. The chrysoberyl mineral is transformed into a synthetic alexandrite crystal using the floating zone process. The surrounding illumination affects the alexandrite crystal\'s color. The alexandrite laser was developed in 1964. BeAl2O4 is the formula for chrysoberyl crystal, a beryllium aluminate. The alexandrite laser has adjustable wavelengths between 700 and 820 nm. Notable characteristics of this laser are its high thermal coefficient, Q-switching, mechanical strength, chemical stability, and CW mode of operation. It is best suited for high power laser applications.[22]

Introduction

A laser is a device that emits coherent light through optical amplification based on stimulated emission. First demonstrated in 1960 by Theodore Maiman, lasers differ from ordinary light sources by their spatial and temporal coherence, enabling them to produce narrow, focused beams with precise frequencies. These properties make lasers essential in numerous applications, including cutting and welding, communication systems, medical procedures, data storage, manufacturing, scientific research, entertainment, and military targeting.

The concept of stimulated emission originated from Albert Einstein in 1916, leading to the development of masers in the 1950s by Charles Townes, Nikolay Basov, and Alexander Prokhorov. Their work later inspired the creation of optical masers, or lasers. Early milestones include Maiman’s ruby laser (1960), the first helium–neon gas laser, and the first semiconductor laser. Despite slow initial commercialization, lasers soon found widespread use—from holography and barcode scanners to CD players and laser surgery.

Laser operation is rooted in quantum physics, involving absorption, spontaneous emission, and stimulated emission. Achieving stimulated emission requires a population inversion, created through pumping methods such as intense light or electric current. Practical lasers use three- or four-level energy systems to store energy efficiently and maintain sustained output.

A typical laser system includes a gain medium, a pumping source, and an optical resonator made of mirrors that reflect and amplify light. Laser beams are highly monochromatic, coherent, and directional. Their wavelength, coherence, divergence, and power depend on the gain medium, cavity design, and stimulated emission characteristics. Lasers can produce continuous beams or extremely short, high-power pulses used in advanced scientific experiments.

Among specialized types, Alexandrite lasers—developed in 1964—use chromium-doped chrysoberyl crystals and operate between 700 and 820 nm. They are valued for their tunability, high thermal capacity, Q-switching ability, mechanical strength, and suitability for high-power applications.

Conclusion

Chromium-doped chrysoberyl lasers are known as Alexandrite lasers. The floating zone procedure is used to convert the chrysoberyl mineral into a synthetic alexandrite crystal. The hue of the alexandrite crystal is influenced by the ambient lighting. In 1964, the alexandrite laser was created. Chrysoberyl crystal, a beryllium aluminate, with the formula BeAl2O4. The wavelengths of the alexandrite laser can be adjusted between 700 and 820 nm. This laser\'s high thermal coefficient, Q-switching, mechanical strength, chemical stability, and CW mode of operation are noteworthy features. High power laser applications are where it works best.[22] The Alexandrite laser is mostly utilized for laser hair removal techniques in cosmetic surgery. Additionally, it is employed in certain medical procedures like laser lithotripsy. Other uses for the alexandrite laser include industrial metal coatings, ceramics, spectroscopy, LIDAR, and laser machining, which includes drilling, etching, and metal marking. [22]

References

[1] Taylor, Nick (2000). Laser: The Inventor, The Nobel Laureate, and The Thirty-Year Patent War. Simon & Schuster. p. 66. ISBN 978-0684835150. [2] Ross T., Adam; Becker G., Daniel (2001). Proceedings of Laser Surgery: Advanced Characterization, Therapeutics, and Systems. SPIE. p. 396. ISBN 978-0-8194-3922-2. [3] \"December 1958: Invention of the Laser\". aps.org. Archived from the original on December 10, 2021. Retrieved January 27, 2022 [4] Semiconductor Sources: Laser plus phosphor emits white light without droop\". November 7, 2013. Archived from the original on June 13, 2016. Retrieved February 4, 2019. [5] Laser Lighting: White-light lasers challenge LEDs in directional lighting applications\". February 22, 2017. Archived from the original on February 7, 2019. Retrieved February 4, 2019. [6] How Laser-powered Headlights Work\". November 7, 2011. Archived from the original on November 16, 2011. Retrieved February 4, 2019. [7] Laser light for headlights: Latest trend in car lighting | OSRAM Automotive\". Archived from the original on February 7, 2019. Retrieved February 4, 2019. [8] Heilbron, John L. (March 27, 2003). The Oxford Companion to the History of Modern Science. Oxford University Press. pp. 447. ISBN 978-0-19-974376-6. [9] Bertolotti, Mario (October 1, 2004). The History of the Laser. CRC Press. pp. 215, 218–219. ISBN 978-1-4200-3340-3. [10] McAulay, Alastair D. (May 31, 2011). Military Laser Technology for Defense: Technology for Revolutionizing 21st Century Warfare. John Wiley & Sons. p. 127. ISBN 978-0-470-25560-5. [11] Renk, Karl F. (February 9, 2012). Basics of Laser Physics: For Students of Science and Engineering. Springer Science & Business Media. p. 4. ISBN 978-3-642-23565-8. [12] LASE\". Collins Dictionary. Retrieved January 6, 2024. [13] \"LASING\". Collins Dictionary. Retrieved January 6, 2024. [14] Strelnitski, Vladimir (1997). \"Masers, Lasers and the Interstellar Medium\". Astrophysics and Space Science. 252: 279–287. Bibcode:1997Ap&SS.252..279S. doi:10.1023/ [15] Chu, Steven; Townes, Charles (2003). \"Arthur Schawlow\". In Edward P. Lazear (ed.). Biographical Memoirs. Vol. 83. National Academy of Sciences. p. 202. ISBN 978-0-309-08699-8 [16] Al-Amri, Mohammad D.; El-Gomati, Mohamed; Zubairy, M. Suhail (December 12, 2016). Optics in Our Time. Springer. p. 76. ISBN 978-3-319-31903-2. [17] Hecht, Jeff (December 27, 2018). Understanding Lasers: An Entry-Level Guide. John Wiley & Sons. p. 201. ISBN 978-1-119-31064-8. [18] https://www.ulsinc.com/learn [19] https://www.fiberoptics4sale.com/blogs/wave-optics/semiconductor-laser-physics [20] https://www.szlaser.com/index.php/wiki/laser-physics/ [21] https://www.britannica.com/technology/laser [22] https://www.azooptics.com/Article.aspx?ArticleID=513

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.