Question

If you were to design a laser, how would you determine the wavelength of light that would be produced?

Asked by: Stuart Searle

 Answer

In a laser there is a medium that is the source as well as the amplifying agent of light. When the molecules of the medium are given some energy they will jump to higher energy levels. When they return to lower energy levels they will emit light with energy equal to the difference in the energies of the levels. This light is the source of laser radiation. Therefore one is bound to the available energy level differences (lines) of the medium.

Then how is this light amplified? The very first photons move in all directions. Some of them will go and hit one of the mirrors in the laser cavity. It gets reflected and goes back into the medium. When a photon that is reflected and got back to the medium hits an excited molecule it will make the molecule go down to the lower energy level by emitting a photon with the same energy, direction, and polarization. These photons get reflected back and forth between two mirrors (for a laser with two mirrors and the medium) This way the photons grow in number and laser light is generated.



Answered by: Ertan Salik, M.A. Physics, USC

Search

Loading



Sponsors

USC University of Southern California Dornsife College Physics and Astronomy Department McMaster University Physics and Astronomy Department

Science Quote

'When I examine myself and my methods of thought, I come to the conclusion that the gift of fantasy has meant more to me than my talent for absorbing positive knowledge.'

Albert Einstein
(1879-1955)

Deal of the Day

Image of Hover Craft Kit. Click on this image for more info. Hover Craft Kit
Regular Price: $29.99
Today's Price: $12.00
Learn the science behind hover craft technology with this cool kit! Buy it now! Deal ends at midnight!

Top Selling

Here are our physics & astronomy bestsellers:
Mini Plasma Ball
Slide Making Kit
Top Secret - Spinning Top
Wood Grain Newtons Cradle
Deluxe 3D Mirascope
Solar Radiometer
Periscope
Solar Science 4M Kit
Ultimate Chemistry Set CHEM C3000
3D Magnetic Field Tube