Lasers History

In 1917 Albert Einstein made the foundations in theory for the laser, but in 1957 the Japanese scientist Jun-Ichi Nishizawa studied and then Charles H. Townes and Arthur Leonard Schawlow began to try making visual lasers instead of the infrared lasers proposed by other scientists. This is where the classic red lasers come from. The name comes from the acronym (Light Amplification stimulated by Emission of Radiation) 

Laser design

A laser is made of 3 parts. Something to give optical feedback, a gain medium, and a mechanism to energize it. Gain mediums amplify light using stimulated emission. The gain medium concentrates one frequency of light and reds the strongest so that's often the color used. And there's also a optical cavity which reflects light that're placed on both ends, one fully reflective and one partially, as they bounce back and forth they go through the gain medium stimulating more light emissions

The impact of the laser

The Laser has many uses including industrial use such as cutting and welding materials, medical applications like surgery, etc. They're also innovative, scientists have now made fiber lasers and solid state lasers that offer high power and efficiency.

Evolution of the laser

The laser has gotten way more powerful over time, reaching its max average output, max pulse energy, max pulse power, etc. And in 2015 they made a white laser using something called a synthetic nanosheet

1: The gain medium amplifies light

2: The energy going back and forth

3: The high reflector is meant to reflect as much light as possible, about 99.9%

4: The output coupler is meant to reflect a small amount of light and reflect a larger portion, this is to control its output power and feedback

5: The laser beam is finally the part that this device produces

DIAGRAM

The end

Sources: 

Wikipedia.org and Cteec.org

Images: From wikipedia.org