A semiconductor laser converts electrical energy into light. This is made possible by using a semiconductor material, whose ability to conduct electricity is between that of conductors and insulators.
By doping a semiconductor with specific amount of impurities the number of negatively charged electrons or positively charged holes can be changed.
Such lasers consists of 2 basic components- 1) An OPTICAL AMPLIFIER and
2) A RESONATOR.
The amplifier is made from direct bandgap semiconductor material based on either GaAs(Galium Arsenide) or InP(Indium Phosphide) substrates .
These are compounds based on the group III and group V elements in the periodic table. Alloys of these materials are formed onto the substrates as layered structures containing precise amounts of other materials.