The Study on the Ruby Laser

Abstract

A solid-state laser that uses a synthetic ruby crystal as its laser medium is called a ruby laser. Maiman created the first successful laser, the ruby laser, in 1960. One of the few solid-state lasers that can emit visible light is the ruby laser. The wavelength of the deep red light it emits is 694.3 nm. Three key components make up a ruby laser: the optical resonator, the pump source, and the laser medium.A single cylinder-shaped ruby crystal (Al2O3: Cr3+) serves as the laser medium or active medium in a ruby laser. The host of sapphire (Al2O3) doped with trace amounts of chromium ions (Cr3+) serves as the laser medium (ruby) in the ruby laser. The ruby\'s thermal characteristics are favorable. [22]

Introduction

The text provides a comprehensive overview of lasers, covering their history, principles of operation, components, characteristics, and applications, with a focus on the ruby laser as the first successful solid-state laser.

Key Points:

1. Definition and Properties of Lasers:

   • A laser (Light Amplification by Stimulated Emission of Radiation) emits coherent light through stimulated emission.

   • Lasers exhibit spatial coherence (focusable, narrow beams), temporal coherence (narrow frequency or ultrashort pulses), and monochromaticity.

   • Laser light is collimated, highly directional, and can be continuous or pulsed, with power ranging from microwatts to over a million watts.

2. History and Development:

   • Einstein (1916) theorized stimulated emission, and Ladenburg (1928) observed it experimentally.

   • Townes, Basov, and Prokhorov developed the maser in the 1950s; Townes and Schawlow proposed the optical maser.

   • Gould coined the term laser, and Theodore Maiman built the first operational laser (ruby laser) in 1960.

   • Subsequent developments included gas lasers (He-Ne) and semiconductor lasers.

3. Laser Operation Principles:

   • Lasers rely on quantum energy levels: electrons in atoms absorb energy (excitation), creating a population inversion where more electrons occupy higher-energy states.

   • Spontaneous emission produces photons randomly, while stimulated emission produces coherent photons, amplifying light in a cascade effect.

   • Three-level lasers (like ruby) produce pulses due to ground-state absorption; four-level lasers enable continuous beams by adding an intermediate energy level.

4. Laser Components and Beam Characteristics:

   • Laser medium: gas, liquid, or solid (e.g., ruby crystal with Cr³? ions).

   • Pump source: energy input (flash lamp or electric current) to achieve population inversion.

   • Optical resonator: mirrors reflect light back and forth, amplifying it; one mirror is partially reflective to allow the beam to exit.

   • Lasers produce narrow, collimated, monochromatic, and coherent beams.

   • Beam divergence depends on wavelength and aperture size; coherence length determines the phase uniformity for applications like holography.

5. Ruby Laser Specifics:

   • First successful laser, emitting deep red light (694.3 nm).

   • Operates as a three-level solid-state laser with a ruby crystal (Al?O? doped with Cr³?) as the medium.

   • Electrons are pumped from ground (E?) to pump state (E?), then relax to metastable state (E?), creating population inversion.

   • Stimulated emission amplifies photons between mirrors; the output escapes through a partially reflecting mirror as coherent laser light.

6. Applications:

   • Industrial: cutting, welding, photolithography.

   • Medical: surgery, skin treatment, eye repair.

   • Consumer: barcode scanners, CD/DVD drives, laser printers.

   • Scientific and military: LiDAR, holography, rangefinding, targeting, and space exploration.

7. Significance:

   • Lasers are distinguished from other light sources by coherence, directionality, and monochromaticity, enabling precise, high-intensity, and versatile applications across multiple fields.

This summary emphasizes how lasers operate, their unique properties, historical development, and practical uses, with a detailed example of the ruby laser’s working mechanism.

Conclusion

Ruby lasers are solid-state lasers that employ artificial ruby crystals as its laser medium. In 1960, Maiman invented the ruby laser, the first practical laser. The ruby laser is one of the few solid-state lasers capable of producing visible light. It emits a deep red light with a wavelength of 694.3 nm. The optical resonator, the pump source, and the laser medium are the three essential parts of a ruby laser.The laser medium or active medium in a ruby laser is a single cylinder-shaped ruby crystal (Al2O3: Cr3+). The ruby laser\'s laser medium is sapphire (Al2O3) doped with trace amounts of chromium ions (Cr3+). The thermal properties of the ruby are advantageous. [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.physics-and-radio-electronics.com/physics/laser/rubylaserdefinitionconstructionworking.html

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.