Laser Construction and Components

If you’re the type that likes taking things apart in order to see how they work then you’ll enjoy this article on the construction and components of lasers. There’s no need to take a hammer and saw to your laser to satisfy your curiosity, we’ll guide you through the internals of a laser in this article.

The components of a laser are generally divided into three major parts. There’s no need to reinvent the wheel here, so we’ll use these same three divisions:

1. Energy source
2. Lasing medium
3. Optical resonator

1. Energy source: the energy source in a laser is, well, the source of the energy! In a regular household light bulb the source of the energy is electricity. Several different sources of energy can be used in a laser which include, but are not limited to, electrical discharge, chemical reactions or intense bursts of light from a flash lamp. In addition, a laser can be used as the energy source for another laser! This is how most of the lasers that we offer work. The lasers that we offer have a pump diode as the source of energy. A pump diode is a type of laser in itself. In a pump diode electricity is used to cause a semi-conducting material to emit photons. So, in a pump diode the source of the energy is electricity, the lasing medium is the semi-conducting material and the optical resonator is the pair of “end-facets” which can be either mirrors or the semi-conducting material itself which is cut so finely as to be reflective. The photons that are emitted from a pump diode are of the 808nm infra-red wavelength.
   
   
2. Lasing medium: the photons from the pump diode then stimulate the atoms in the lasing medium. In our green lasers the first lasing medium is a Nd:YVO4 crystal. Nd:YVO4 is an abbreviation of the composition of the crystal which is neodymium doped yttrium orthvanadate. This crystal emits photons in the 1064nm infra-red wavelength.
   
   
3. Optical resonator: the optical resonator is the mechanism by which the photons are directed back into the lasing medium in order to stimulate further photon emission. In the pump diode the optical resonator was a pair of end-facets. In the Nd:YVO4 lasing medium the optical resonator is a semi-reflective optical coating on the ends of the crystal. The Nd:YVO4 emits photons in the 1064nm infra-red wavelength.

After the photons exit the lasing medium and the optical resonator that surrounds it, they are collimated by optics into a tight beam. The beam then exits the aperture of the laser housing after passing through an infra-red filter. Infra-red filters contain any excess infra-red radiation inside the laser unit.

Ok, so what about that awesome green color you get from one of our X-Series lasers? There is an extra step that is necessary in order to achieve this color (wavelength). After the photons exit the Nd:YVO4 crystal they pass through another crystal, this time a KTP crystal, the composition of which is potassium titanium oxide phosphate. The KTP crystal is a frequency doubling crystal. 1064nm infra-red light enters the KTP crystal and is frequency doubled to 532nm (green).    

Picture: summary of the composition of a laser

Click here for our less technical and more theoretical explanation of how a laser works.

NOVAlasers wishes you fun exploring!

Copyright 2006 NOVAlasers