How do lasers work?
A laser is a device that generates a narrow, focused beam of light. Unlike ordinary light, which contains many colors and spreads in all directions, laser light is mostly one color, with coherent waves that move together in step.
These properties result from stimulated emission, a quantum process in which one photon nudges an excited atom to release an identical photon, triggering a chain reaction that builds a concentrated, coherent beam. A laser's color corresponds to its wavelength and photon energy, determining how it interacts with materials and the tasks it can perform. This ranges from engraving microchips and transmitting data to cutting metal and performing delicate medical procedures.
Because of this precision and intensity, lasers have become indispensable to modern life. Today, they are used in countless everyday applications — from barcode scanners and high-speed internet to medical imaging and advanced manufacturing. Lasers are also key to emerging technologies and national security. They let researchers cool and trap atoms, build quantum bits and explore the universe in new ways — work that underpins breakthroughs in quantum communication, sensing, fusion energy and even tools that can measure ripples in space-time.
From curiosity to capability
When Theodore Maiman first demonstrated the laser in 1960, its practical uses and commercial value were far from clear. Early advances were driven by industrial laboratories and the U.S. Department of Defense (now the U.S. Department of War), which explored a range of laser designs based on different materials and techniques. These early lasers, however, were often room-sized and extremely energy-intensive, making them costly and impractical.
In the 1970s, when lasers didn't produce quick profits, companies began to scale back research, and NSF stepped in to fill the gap. Over the following decades, the agency's support made lasers more precise, faster and energy-efficient, while also developing novel materials for new lasers.
One example is NSF's support of Gérard Mourou and his collaborators beginning in the 1980s. Their development of chirped-pulse amplification enabled ultrafast, high-power laser pulses. This breakthrough — later recognized with a portion of the 2018 Nobel Prize in physics — revolutionized laser science, sparked new research avenues and led to real-world applications, including precision industrial machining, LASIK eye surgery and fundamental physics research.
Lasers at work
Sustained NSF investments have driven advances across all aspects of laser technology.
Fiber optics
The NSF Lightwave Technology Program in the 1980s supported research crucial to the development of optical fibers — the physical strands conveying light signals — which enable lasers to transmit vast amounts of data at high speeds over long distances.
Concurrently, NSF's broader support for materials research advanced the fields of ceramics/glass engineering and solid-state physics. This cross-disciplinary effort was essential to scaling the technology into a global communications infrastructure that now underpins the internet, mobile devices and other high-bandwidth communications applications.
Noninvasive imaging
The NSF Lightwave Technology program also supported the development of optical coherence tomography (OCT). Initially used in the late 1980s to detect faults in optical fibers, OCT was later adapted by pioneering biomedical researchers like NSF-funded James Fujimoto.
Alongside collaborators, his work in the early 1990s led to noninvasive imaging of microscopic structures in the eye. Today, it is widely employed to monitor retinal diseases, assess coronary plaque buildup and guide surgical procedures such as LASIK.
LASIK
The NSF Science and Technology Centers program supported researchers at the Center for Ultrafast Optical Science (later renamed to the Gérard Mourou Center for Ultrafast Optical Science), who developed the laser technology and surgical procedures for bladeless LASIK, a precise, minimally invasive corrective eye surgery.
Additional NSF Small Business Innovation Research helped bring technology to patients.
Metal additive manufacturing
NSF support in the 1980s helped develop laser power bed fusion, a technique that uses lasers to fuse small particles of plastic, metal, ceramic or glass into 3D objects. Today, it enables metal additive manufacturing across aerospace, biomedical and automotive industries.
Laser guide stars
NSF plays a critical role in advancing laser guide star (LGS) technology for astronomical adaptive optics by providing funding for development, infrastructure and operation at major observatories like Keck, Gemini and the Center for Adaptive Optics.
These LGS systems create temporary artificial "stars" in the upper atmosphere to correct for atmospheric distortion, allowing ground-based telescopes to produce significantly sharper, clearer images of the night sky.
Detecting ripples in spacetime
The agency's continued support for the NSF Laser Interferometer Gravitational-Wave Observatory (NSF LIGO) since the 1990s enabled the first-ever detection of gravitational waves in 2015, confirming ripples in space-time and earning the researchers behind the discovery the 2017 Nobel Prize in physics.
Mapping in 3D
NSF's long-term investment in the National Center for Airborne Laser Mapping (NCALM) revolutionized the use of high-resolution lidar for scientific discovery.
By measuring the time it takes for laser pulses to bounce off the Earth's surface, this technology creates precise 3D maps that "see" through dense vegetation to reveal hidden archeological sites or track coastal erosion.
NSF's continuous support for NCALM (since 2003) and lidar's advancement have consequently been foundational to the safe navigation of autonomous vehicles and the open-access data provided through the OpenTopography project.
Etching semiconductors
Since the 1960s, sustained NSF funding has helped bridge the gap between plasma physics research and commercial manufacturing. This support facilitated the industry-wide shift from wet to dry (plasma-based) etching. In this process, lasers are used to create and manipulate plasma — a super-hot, charged gas — to etch the nanoscale features needed to produce increasingly compact and complex semiconductor devices.
Through strategic initiatives like Engineering Research Centers and the Grant Opportunities for Academic Liaison with Industry program, NSF's sustained support has continued to scale advanced laser and plasma diagnostics. These efforts have unveiled ultraprecise chip-etching technology being successfully transitioned from the lab to factory floors, where it enables the production of next-generation AI electronics.
Facilitating research in new technologies
NSF's support of the Engineering Research Center for Extreme Ultraviolet Science and Technology in the 2000s led to the development of compact ultrafast laser sources in the extreme UV and X-ray spectral regions.
In the 2010s, NSF-supported researchers created the world's shortest laser pulses, including a 53-attosecond pulse in 2017, giving scientists new tools to observe electrons in motion.
Compact ultrafast sources are opening entirely new fields of study, such as quantum materials, and paving the way for emerging technologies like next-generation atomic clocks.
The nation's most powerful laser
In 2025, researchers using the NSF-funded Zettawatt-Equivalent Ultrashort laser pulse System (NSF ZEUS) generated a 2 PetaWatt 25-femosecond-pulse — making NSF ZEUS the most powerful laser in the United States.
As an open user facility and a cutting-edge platform for discovery research in both fundamental and applied sciences, NSF ZEUS promises to advance the frontiers in everything from laser-driven particle accelerators to medicine and national security.
Igniting fusion
Laser-driven fusion uses high-energy beams to compress and heat fuel until it reaches the extreme conditions necessary for atomic nuclei to fuse, releasing massive amounts of energy.
Pushing the boundaries of scientific exploration, laser technology and optical materials necessary to further increase the energy and power of future lasers is the NSF OPAL project.
This next-generation laser facility will enable the study of matter under extreme physical conditions (like the pressures found in the cores of giant planets), while paving the way for breakthroughs in energy research.
Learn more about NSF's investment in Fusion Enabling Science and Technology.
Lighting the path ahead
From everyday tools like fiber-optic communications to the most powerful laser in the U.S., NSF-supported researchers continue to develop state-of-the-art laser technologies. With their unique capabilities, these lasers are paving the way to advancements such as improved materials, faster memory chips, better medical imaging and more targeted drug delivery, bolstering national security, prosperity and economic growth.