Maser

A maser is a special device that creates very clear and steady electromagnetic waves, especially microwaves. It does this using a process called stimulated emission. The name “maser” comes from “microwave amplification by stimulated emission of radiation.” Important scientists like Nikolay Basov, Alexander Prokhorov, and Joseph Weber first came up with the idea of a maser in 1952. Then, Charles H. Townes, James P. Gordon, and Herbert J. Zeiger built the very first maser at Columbia University in 1953. For their work, Townes, Basov, and Prokhorov won the 1964 Nobel Prize in Physics.

Masers are very important for keeping very accurate time in atomic clocks. They are also used in radio telescopes to make very clear signals, and they help spacecraft communication work better when talking to spacecraft far away from Earth.

The maser was actually the inspiration for another famous device called the laser. Lasers work in much the same way but create waves that we can see, like the light from a flashlight. The idea for the laser came from the maser, and it was finally built in 1960. At first, this new device was called the “optical maser,” but later it was changed to laser, short for “light amplification by stimulated emission of radiation.”

History

The idea for a maser was first shared by Joseph Weber from the University of Maryland, College Park in June 1952, and also by Nikolay Basov and Alexander Prokhorov from the Lebedev Institute of Physics around the same time.

Later in 1953, Charles Hard Townes, James P. Gordon, and H. J. Zeiger made the first maser at Columbia University. They used special molecules to create strong microwave signals. Their work helped lead to the development of lasers a few years later. In 1964, Townes, Basov, and Prokhorov received the Nobel Prize in Physics for their important contributions to this field.

Technology

The maser is a tool that uses special energy to make strong, clear waves, much like how a laser works. It started with an idea from Albert Einstein in 1917. When tiny parts called atoms get extra energy, they can make waves that match the material they are made from.

By placing these materials inside a special space, it helps create waves that stay the same for a long time.

Some common types

• Atomic beam masers
  • Ammonia maser
  • Free electron maser
  • Hydrogen maser
• Gas masers
  • Rubidium maser
• Liquid-dye and chemical laser
• Solid state masers
  • Ruby maser
  • Whispering-gallery modes iron-sapphire maser
• Dual noble gas maser (The dual noble gas of a masing medium which is nonpolar.)

21st-century developments

In 2012, scientists from the National Physical Laboratory and Imperial College London made a maser that works at normal room temperature. They used special materials to help it work.

In 2018, a group from Imperial College London and University College London showed how to make the maser work without stopping, using tiny changes in special diamonds.

In 2025, a team from Northumbria University built a maser that doesn’t need much power and works at room temperature, using a simple light source to start it.

Uses

Masers are very important tools for keeping exact time. They act like special clocks and are used in many places where very accurate timing is needed.

In the past, masers were also used to make weak microwave signals stronger, especially in telescopes that look at space. One famous use was to help receive pictures from the Mariner IV space probe as it flew by Mars. The maser used very cold helium to work better and could make very clear pictures even though the signal from the probe was very weak.

The hydrogen maser is a special kind of maser that helps set the official international time standard. It works by using the natural vibrations of hydrogen atoms to create a very stable and precise frequency signal.

Astrophysical masers

Main article: Astrophysical maser

Maser-like natural emissions have been found in space, often called "superradiant emission." These come from molecules such as water (H₂O), hydroxyl radicals (•OH), methanol (CH₃OH), formaldehyde (HCHO), silicon monoxide (SiO), and carbodiimide (HNCNH). Water molecules in areas where stars are forming can emit radiation at about 22.0 GHz, making one of the brightest lines in radio waves. Some water masers also emit radiation at a frequency of 96 GHz.

Very strong masers linked to active centers of galaxies are called megamasers and can be up to a million times stronger than masers found around stars.

Terminology

The word maser originally stood for "microwave amplification by stimulated emission of radiation". It described devices that sent out waves in the microwave part of the electromagnetic spectrum.

Later, scientists started using the idea behind masers for other types of waves. Because of this, some suggested changing the name to "molecular amplification by stimulated emission of radiation." When the laser was created, some people used the term optical maser, but this was replaced by laser. Today, we usually call devices that send out X-ray through infrared waves lasers, and those that send out microwave waves and lower are called masers.