Brought to you by: Jonathan E. Mace What is a… What make a laser so special? Wave / Particle Duality of Light Wave-like Properties -Wavelength/Frequency -Interference -Phase Particle-like Properties -Photons -Momentum -Quantum mechanics Lasers Use Both!!! Absorption and Emission of Light Electrons can only go to certain energy levels. They can only absorb certain frequencies of light. Ground State Electrons Electrons emit lightExcited State at the same discrete Electron s frequencies at which they absorb when traveling between energy levels. The two types of emission Excited atoms decay to a lower energy state and emit light in random directions. The different atoms can emit light at different times and may not undergo the same transitions. Light from the decay of one excited atom interacts with another similarly excited atom causing that element to emit light This light produced is: in phase, directional, and monochromatic. Optical Resonant Cavity Pumping Source Mirror Total reflection Atoms Mirror Partial reflection Pump Cycle Pumping Source Excited Atoms Emission and Lasing Pumping Source Why are lasers important?