How Lasers Work - Stuff You Should Know Recap

Podcast: Stuff You Should Know

Published: 2026-02-12

Duration: 47 minutes

Summary

Lasers are more than the cool beams we see in movies; they are devices that generate light through a process called stimulated emission. This episode covers the science behind lasers and their various applications, from supermarket scanners to cutting-edge nuclear fusion research.

What Happened

Lasers, an acronym for Light Amplification by Stimulated Emission of Radiation, are fascinating devices that have revolutionized many fields. Unlike regular light, lasers emit light that is monochromatic, coherent, and collimated, meaning it travels in the same direction with photons in phase. This unique property makes lasers highly versatile for applications ranging from mundane tasks like reading UPC codes to advanced scientific research.

The theoretical foundation for lasers was laid in the early 1900s by Albert Einstein, who introduced the concept of stimulated emission and proposed that light consists of discrete packets called photons. The first functional laser was devised by Theodore Maiman in 1960, using a ruby crystal, marking a significant milestone in laser technology. Prior to this, Charles Townes had developed the maser, which used microwaves and was a precursor to the laser.

Lasers come in various forms, including solid-state, gas, fiber, and dye lasers, each utilizing different gain mediums such as crystals, gases, or organic dyes. Solid-state lasers often use crystals doped with rare earth elements, while gas lasers might use carbon dioxide or argon, excited by an electrical current. Fiber lasers stand out for their efficiency in telecommunications, converting over 50% of electricity into light.

In addition to their scientific and industrial applications, lasers have significant medical uses. They are employed in surgeries for their precision and minimal tissue damage and in cosmetic procedures like tattoo removal and Lasik eye surgery, with the latter offering improved vision outcomes for many patients. Lasers are also pivotal in military technology, serving as directed energy weapons to neutralize drones.

Pulse lasers, which emit energy in short bursts, can be incredibly powerful. For instance, the ZEUS laser at the University of Michigan generates a pulse just 25 quintillionths of a second long, releasing 3 petawatts of energy - 100 times the world's total electrical output in a single burst. Such power allows researchers to simulate conditions found inside stars and black holes.

The episode also touches on the breakthrough in nuclear fusion research achieved in 2022 at Lawrence Livermore Lab, where lasers were used to achieve a net energy gain for the first time. This achievement could pave the way for future clean energy solutions. Lasers' versatility and the sheer breadth of their applications demonstrate their significant impact on science and technology.

Key Insights

• The ZEUS laser at the University of Michigan can release energy 100 times the world's total electrical output in just 25 quintillionths of a second. This pulse laser simulates the extreme conditions inside stars and black holes, proving that sometimes the most powerful forces come in the shortest bursts.
• Lasers owe their existence to Albert Einstein's early 1900s idea that light consists of discrete packets called photons. This concept laid the groundwork for Theodore Maiman's creation of the first functional laser in 1960, showing that even the most futuristic tech can have roots in century-old theories.
• Fiber lasers are like the overachievers of the laser world, converting over 50% of electricity into light, making them a telecommunications powerhouse. This efficiency is what keeps our high-speed internet humming, proving that sometimes it's the unseen infrastructure that makes our digital lives possible.
• In 2022, lasers achieved a sci-fi dream: a net energy gain in nuclear fusion at Lawrence Livermore Lab. This breakthrough hints at a future of clean energy, where lasers might just be the key to unlocking the sun's power right here on Earth.