Who built the first laser and where?

The first laser was built in 1960 by Theodore Maiman at Hughes Research Laboratories.

How does a laser's light differ from that of other light sources in terms of coherence?

A laser differs from other light sources because it emits light that is coherent, meaning its waves are in phase and travel together.

What does temporal coherence imply for a laser's output?

Temporal coherence implies that a laser can emit light with a very narrow frequency spectrum and can be used to produce ultrashort pulses of light.

What was the precursor to the laser, and what did its name signify?

The first device using amplification by stimulated emission operated at microwave frequencies and was called a maser, which stood for "microwave amplification by stimulated emission of radiation."

What is the distinction between lasers and masers based on frequency?

Lasers operate at frequencies higher than microwaves (approximately above 300 GHz), while masers operate at microwave or lower radio frequencies.

What are photons, and how are they involved in atomic energy levels?

Photons are the quanta of electromagnetic radiation, and they are released and absorbed from energy levels within atoms and molecules.

What is stimulated emission, and what conditions are necessary for it to occur?

Stimulated emission is a process where the release of a photon is triggered by the nearby passage of another photon. For this to happen, the triggering photon must have similar energy (wavelength) to the one that could be released, and the atom or molecule must be in a suitable excited state.

What is "population inversion" and why is it necessary for lasing?

Population inversion is achieved when the number of particles in one excited state exceeds the number of particles in a lower-energy state. This condition ensures that stimulated emission occurs more frequently than absorption, leading to light amplification.

What are the three essential components of a laser?

A laser consists of a gain medium, a mechanism to energize it (pumping), and something to provide optical feedback (like an optical cavity).

What are the two primary modes of laser operation?

Lasers can operate in either continuous-wave (CW) mode, where the power output is constant over time, or pulsed mode, where the output consists of pulses of light.

What foundational theoretical work by Albert Einstein in 1917 laid the groundwork for lasers and masers?

In 1917, Albert Einstein established the theoretical foundations for lasers and masers by deriving probability coefficients for the absorption, spontaneous emission, and stimulated emission of electromagnetic radiation.

Who constructed the first gas laser, and what gases did it use?

Ali Javan, William R. Bennett Jr., and Donald R. Herriott constructed the first gas laser using helium and neon.

What significant advancement in semiconductor lasers was achieved in 1970 by Alferov, Hayashi, and Panish?

In 1970, Zhores Alferov, Izuo Hayashi, and Morton Panish independently developed room-temperature, continual-operation diode lasers using the heterojunction structure.

What are some common types of gas lasers and their typical uses?

Common gas lasers include the Helium-Neon (HeNe) laser for optical research and education, Carbon Dioxide (CO2) lasers for industrial cutting and welding due to their high power and efficiency, and Argon-ion lasers used for various lines between 351 and 528.7 nm.

What defines an excimer laser, and what are its typical applications?

Excimer lasers use molecules that exist only in an excited electronic state (excimers or exciplexes) as their lasing medium. They typically operate at ultraviolet wavelengths and are used in semiconductor photolithography and LASIK eye surgery.

What is a solid-state laser, and what are some common dopant materials?

Solid-state lasers use a crystalline or glass rod doped with ions that provide the energy states for lasing. Common dopants include Neodymium, Ytterbium, Holmium, Thulium, and Erbium.

What is a fiber laser, and what are its advantages regarding cooling and beam distortion?

A fiber laser uses light guided by total internal reflection within an optical fiber as its gain medium. This allows for long gain regions, efficient cooling due to a high surface area-to-volume ratio, and reduced thermal distortion of the beam.

How do semiconductor lasers, or laser diodes, generate light?

Semiconductor lasers are diodes that are electrically pumped; the recombination of electrons and holes created by the applied current introduces optical gain.

What makes dye lasers highly tunable or capable of producing very short pulses?

Dye lasers use an organic dye as the gain medium, and the wide gain spectrum of available dyes allows for high tunability or the generation of very short pulses, on the order of femtoseconds.

What is unique about free-electron lasers (FELs) regarding their tunable range?

Free-electron lasers have the widest frequency range of any laser type, currently tunable from microwaves through terahertz radiation, infrared, visible spectrum, to soft X-rays.

What was the initial perception of the laser's utility when it was first invented?

When the laser was first invented, it was often called "a solution looking for a problem."

How have lasers become ubiquitous in modern society?

Lasers have become ubiquitous, finding utility in thousands of varied applications across consumer electronics, information technology, science, medicine, industry, law enforcement, entertainment, and the military.

What role do lasers play in fiber-optic communication?

Fiber-optic communication relies on multiplexed lasers in dense wave-division multiplexing (WDM) systems to transmit large amounts of data over long distances.

What were some of the first widely noticeable consumer applications of lasers?

The first widely noticeable use was the supermarket barcode scanner, introduced in 1974, followed by the laserdisc player in 1978, and then the common compact disc player in 1982.

What are some medical uses of lasers mentioned in the text?

Lasers are used in medicine for laser surgery (especially eye surgery), laser healing (photobiomodulation therapy), kidney stone treatment, ophthalmoscopy, and cosmetic skin treatments.

How are lasers used to treat cancer?

Lasers are used to treat cancer by shrinking or destroying tumors or precancerous growths, particularly superficial cancers, and through techniques like laser-induced interstitial thermotherapy (LITT).

What is low-level laser therapy (LLLT), and what are its claimed effects?

LLLT involves applying low-power light from lasers or LEDs to the body's surface, claimed to stimulate healing, relieve pain, and enhance cell function.

What is a laser weapon, and what is a major challenge in its deployment?

A laser weapon is a directed-energy weapon that uses lasers to inflict damage. A major challenge is atmospheric thermal blooming, which is exacerbated by conditions like fog, smoke, or dust.

How can lasers be used as incapacitating non-lethal weapons?

Lasers can cause temporary or permanent vision loss when directed at the eyes, serving as incapacitating non-lethal weapons.

What is the typical power output of lasers used as laser pointers?

Lasers used as laser pointers typically have an output power of 1-5 mW.

What is the power range for lasers commonly used in micro-machining?

Commercially available solid-state lasers used for micro-machining typically have an output power of 1-20 W.

Why are even low-power lasers potentially hazardous to human eyesight?

Even low-power lasers can be hazardous because their coherent, low-divergence light can be focused by the eye into an extremely small spot on the retina, causing localized burning and permanent damage.

What does a Class 2 laser safety rating signify?

A Class 2 laser is considered safe during normal use because the blink reflex of the eye prevents damage, typically for lasers up to 1 mW.

What is the hazard level for Class 4 lasers?

Class 4 lasers, with power of 500 mW or more, can burn skin, and even scattered light can cause eye and/or skin damage.

What theoretical work by Charles H. Townes and Arthur Leonard Schawlow was foundational for the laser?

Townes and Schawlow's theoretical study of infrared "optical masers" and their subsequent publication of theoretical calculations in the Physical Review were foundational.

Who is credited with coining the acronym LASER and describing its essential components in a notebook?

Gordon Gould is credited with coining the acronym LASER and describing the elements required to construct one in his notebook.

What was the first functioning laser made of, and what color was its light?

Theodore Maiman's first functioning laser used a flashlamp-pumped synthetic ruby crystal and produced red laser light.

What is the difference between spatial and temporal coherence in laser light?

Spatial coherence relates to the ability of a laser beam to be focused to a tight spot and stay narrow over distances, while temporal coherence relates to the phase correlation of the light wave over distance, implying a single frequency and narrow spectrum.

What is the significance of the National Ignition Facility laser system?

The National Ignition Facility uses a 192-beam, 1.8-megajoule laser system capable of 700 TW peak power, used for inertial confinement fusion and nuclear weapons research.

What is the peak power of the world's most powerful laser as of 2019, and where is it located?

The world's most powerful laser as of 2019 has a peak power of 10 PW (petawatts) and is located at the ELI-NP facility in Măgurele, Romania.

What is the meaning of "eye-safe" for infrared lasers, and what are its limitations?

Infrared lasers with wavelengths longer than approximately 1.4 micrometers are often called "eye-safe" because the cornea absorbs the light, protecting the retina. However, this label is misleading for high-power or Q-switched lasers, which can still burn the cornea.

What international protocol bans weapons designed to cause permanent blindness?

The Protocol on Blinding Laser Weapons bans the use of weapons specifically designed to cause permanent blindness.

What are some common dopant materials used in solid-state lasers?

Common dopants for solid-state lasers include Neodymium, Ytterbium, Holmium, Thulium, and Erbium.

What is a "bubble laser," and what unique output does it produce?

A bubble laser is a type of dye laser that uses a bubble as its optical resonator, producing whispering gallery modes that result in a frequency comb output.

What are VCSELs, and how do they differ from conventional laser diodes in emission direction?

VCSELs (Vertical Cavity Surface-Emitting Lasers) are semiconductor lasers whose emission direction is perpendicular to the wafer surface, typically producing a more circular output beam than conventional laser diodes.

What is the purpose of a laser beam profiler?

A laser beam profiler is used to measure the intensity profile, width, and divergence of laser beams.

What is the difference between continuous-wave (CW) and pulsed laser operation?

Continuous-wave (CW) lasers provide a constant power output over time, while pulsed lasers emit light in discrete pulses, often used for applications requiring high energy or peak power.

What are the key components of a typical laser as depicted in diagrams?

Components of a typical laser include the gain medium, the laser pumping energy source, a high reflector, an output coupler, and the resulting laser beam.

Laser Wiki: Illuminating Light: The Science and Application of Lasers

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What is a Laser?

The Acronym

The term "laser" originated as an acronym for light amplification by stimulated emission of radiation. It describes a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation.

Coherent Light

Lasers are distinguished by their ability to emit light that is coherent. This means the light waves are in phase spatially and temporally, allowing for precise focusing into tight spots and narrow beams that maintain their direction over great distances.

The First Laser

The first laser was constructed in 1960 by Theodore Maiman at Hughes Research Laboratories. This groundbreaking achievement built upon theoretical work by Charles H. Townes and Arthur Leonard Schawlow, and the optical amplifier patent by Gordon Gould.

Fundamental Principles

Stimulated Emission

The core mechanism is stimulated emission, where a passing photon triggers an excited atom to release an identical photon. This process, predicted by Albert Einstein, requires a material with metastable states and a population inversion (more atoms in an excited state than a lower one) to amplify light.

Pumping and Gain Medium

A laser requires a gain medium (gas, liquid, solid, or plasma) that can amplify light. This medium is energized through a process called pumping, typically using an electric current or light source, to achieve a population inversion.

Optical Cavity

Feedback is provided by an optical cavity, usually formed by two mirrors. Light bounces between these mirrors, passing through the gain medium and being amplified. One mirror, the output coupler, is partially transparent, allowing a coherent beam to exit the laser.

Laser Design Elements

Gain Medium

The heart of the laser, this material (e.g., ruby crystal, gas mixture, semiconductor) possesses specific energy levels that facilitate stimulated emission. Its properties dictate the laser's wavelength and output characteristics.

Pumping Mechanism

This is the energy source that excites the gain medium. It can be an electrical discharge, flashlamps, or even another laser, providing the necessary energy to create a population inversion.

Resonator Mirrors

A pair of mirrors forms the optical cavity. A high reflector reflects nearly all light back into the gain medium, while the output coupler allows a fraction of the amplified light to escape as the laser beam. The precise alignment and reflectivity of these mirrors are crucial.

Underlying Physics

Stimulated vs. Spontaneous Emission

While spontaneous emission releases photons randomly, stimulated emission releases identical photons when triggered by an incoming photon of the correct energy. This coherence is fundamental to laser operation.

Quantum Principles

Laser operation is rooted in quantum mechanics, specifically the interaction of electrons with electromagnetic fields. Energy levels within atoms and molecules are quantized, dictating the specific wavelengths of light that can be absorbed or emitted.

Free-Electron Lasers

Unlike conventional lasers relying on atomic energy levels, free-electron lasers (FELs) use a beam of relativistic electrons passing through a magnetic field. This allows for a wide tuning range from microwaves to X-rays, offering unparalleled spectral flexibility.

Modes of Operation

Continuous-Wave (CW)

CW lasers emit a constant, steady beam of light. This mode is achieved when the pumping source provides energy continuously, maintaining a stable population inversion. Many applications, from barcode scanners to scientific instruments, rely on CW operation.

Pulsed Operation

Pulsed lasers emit light in discrete bursts. This can be achieved through techniques like Q-switching (rapidly changing the cavity's quality factor to build up energy for a high-power pulse) or mode-locking (synchronizing multiple laser modes to create extremely short pulses, often femtoseconds in duration).

Pulsed Pumping

In some cases, pulsed operation is a consequence of the pumping mechanism itself. Lasers requiring very fast energy delivery, or those with short excited-state lifetimes, are often pumped by pulsed sources, leading to pulsed laser output.

Historical Development

Theoretical Foundations

The theoretical groundwork for lasers was laid by Albert Einstein in 1917 with his work on stimulated emission. Later, work on masers (microwave amplification by stimulated emission of radiation) by Charles Townes and others paved the way for optical masers, or lasers.

Early Innovations

Gordon Gould coined the term "LASER" and proposed key concepts like the open resonator. Theodore Maiman built the first working laser in 1960 using a ruby crystal, followed by the development of gas lasers (like HeNe) and semiconductor lasers.

Technological Advancements

From early pulsed ruby lasers to continuous-wave gas lasers and efficient semiconductor diodes, laser technology has seen rapid evolution. Innovations in materials, pumping techniques, and optical cavities have led to lasers with diverse wavelengths, powers, and pulse durations.

Diverse Applications

Information & Communication

Lasers are integral to modern communication, powering fiber-optic networks with high-speed data transmission. They are also found in consumer electronics like CD/DVD players, barcode scanners, and laser printers.

Industry & Manufacturing

In industry, lasers are used for precision cutting, welding, marking, and engraving materials. Advanced manufacturing processes like selective laser sintering and melting rely on lasers for additive manufacturing (3D printing).

Medicine & Science

Medical applications include laser surgery (especially in ophthalmology), cosmetic treatments, and cancer therapy. Scientifically, lasers are vital tools for spectroscopy, interferometry, laser cooling, and metrology.

Power and Applications

Power Spectrum

Laser power varies dramatically, from milliwatts for pointers to kilowatts for industrial cutting. Peak power in pulsed lasers can reach terawatts or petawatts, enabling extreme applications like inertial confinement fusion.

Average Power	Typical Use
1–5 mW	Laser pointers
5 mW	CD-ROM drive
5–10 mW	DVD player or DVD-ROM drive
100 mW	High-speed CD-RW burner
250 mW	Consumer 16× DVD-R burner
400 mW	DVD 24× dual-layer recording
1 W	Green laser in Holographic Versatile Disc prototype development
1–20 W	Majority of commercial solid-state lasers for micro machining
30–3000 W	Industrial laser cutting and welding (CO₂ lasers)
700 TW – 10 PW	High-energy physics experiments (e.g., National Ignition Facility)

Military & Law Enforcement

Lasers are employed in military applications for target designation, missile defense, and countermeasures. Law enforcement uses LIDAR for traffic enforcement and lasers for forensic fingerprint detection.

Hobbies & Entertainment

Hobbyists utilize salvaged laser diodes for projects, and lasers are central to entertainment, from optical disc playback to dazzling laser light shows and holographic displays.

Safety Considerations

Eye Hazards

Even low-power lasers can cause permanent eye damage due to their focused, coherent beams. Lasers are classified by hazard level (Class 1 to Class 4), with higher classes requiring stringent safety protocols and protective eyewear.

Aviation & Other Risks

Lasers can pose risks to aviation by distracting or blinding pilots. While infrared lasers are often termed "eye-safe," high-power beams at these wavelengths can still cause corneal burns. Camera sensors can also be susceptible to laser damage.

Warning Symbols

Standardized warning symbols, such as the European Class 2 warning or US laser labels, are crucial for identifying laser hazards. Understanding these labels is essential for safe operation and handling.

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References

WDM optical communication. science.gov.

Dalrymple B.E., Duff J.M., Menzel E.R. "Inherent fingerprint luminescence â detection by laser". Journal of Forensic Sciences, 22(1), 1977, 106â115

Dalrymple B.E. "Visible and infrared luminescence in documents : excitation by laser". Journal of Forensic Sciences, 28(3), 1983, 692â696

A full list of references for this article are available at the Laser Wikipedia page

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Important Notice

This content has been generated by an AI and is intended for educational and informational purposes only. It is based on publicly available data and may not be exhaustive or entirely up-to-date.

This is not professional advice. The information provided is not a substitute for expert consultation in physics, engineering, or any related field. Always refer to official documentation and consult qualified professionals for specific applications or safety concerns.

The creators of this page are not responsible for any errors, omissions, or actions taken based on the information presented herein.

Illuminating Light

💡 Dive in with Flashcard Learning! 💡

What is a Laser? 💡

✨ The Acronym

🌟 Coherent Light

🔬 The First Laser

Fundamental Principles ⚛️

⚡ Stimulated Emission

💡 Pumping and Gain Medium

🪞 Optical Cavity

Laser Design Elements ⚙️

🔬 Gain Medium

🔋 Pumping Mechanism

🪞 Resonator Mirrors

Underlying Physics 🌌

✨ Stimulated vs. Spontaneous Emission

⚛️ Quantum Principles

🚀 Free-Electron Lasers

Modes of Operation 🔄

〰️ Continuous-Wave (CW)

⚡ Pulsed Operation

💥 Pulsed Pumping

Historical Development ⏳

📜 Theoretical Foundations

💡 Early Innovations

🚀 Technological Advancements

Diverse Applications 🌐

💻 Information & Communication

🏭 Industry & Manufacturing

⚕️ Medicine & Science

Power and Applications 📊

📏 Power Spectrum

🛡️ Military & Law Enforcement

🎮 Hobbies & Entertainment

Safety Considerations ⚠️

👁️ Eye Hazards

✈️ Aviation & Other Risks

📜 Warning Symbols

Teacher's Corner 🧑‍🏫

Edit and Print this course in the Wiki2Web Teacher Studio

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❓ Test Your Knowledge! ❓

Gamer's Corner 🎮

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References

📜 References

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To report an issue with this page, or to find out ways to support the mission, please click here.

Disclaimer ⚖️

📜 Important Notice

Dive in with Flashcard Learning!

What is a Laser?

The Acronym

Coherent Light

The First Laser

Fundamental Principles

Stimulated Emission

Pumping and Gain Medium

Optical Cavity

Laser Design Elements

Gain Medium

Pumping Mechanism

Resonator Mirrors

Underlying Physics

Stimulated vs. Spontaneous Emission

Quantum Principles

Free-Electron Lasers

Modes of Operation

Continuous-Wave (CW)

Pulsed Operation

Pulsed Pumping

Historical Development

Theoretical Foundations

Early Innovations

Technological Advancements

Diverse Applications

Information & Communication

Industry & Manufacturing

Medicine & Science

Power and Applications

Power Spectrum

Military & Law Enforcement

Hobbies & Entertainment

Safety Considerations

Eye Hazards

Aviation & Other Risks

Warning Symbols

Teacher's Corner

True or False?

Test Your Knowledge!

Gamer's Corner

Discover other topics to study!

References

Feedback & Support

Disclaimer

Important Notice