laser power point

The electromagnetic spectrum
•Energy level diagram representation
•Spontaneous and stimulated emission, absorption
•The laser concept: rate equations, population inversion, amplification
•Properties of laser beams
•Autocorrelation: characterizing femtosecond laserflux(d?) in the material due to the photon beam?SdzSd???????????=? time)ofunit (per absorption stim. toduephotons of #in change time)ofunit (per emission stim. toduephotons of #in changeSdzdtdN- dtdNSd??Energy Transfer Processes: QuantitativelyLevel 2Level 1
For spontaneous emission:21 to22NWdtdN?=Forstimulatedemission:12 to12NWdtEnergy Transfer Processes•Stimulated emission–electron can be knocked down from level 2 to level 1 •Stimulated absorption–electron can be raisedSame idea as spontaneous emission except we MAKE it happen by sending in an EM wave of frequency f0
A photon is given off with the energyInvented in 1958 by Charles Townes and Arthur Schawlow of Bell Laboratories•Was based on Einstein’s idea of the “particle-wave duality”of light, more than 30 years earlier•Originally called MASER (m=“microwaveTo raise an electron from one energy level to another, “input”energy is required
•When falling from one energy level to another, there will be an energy “output”
•Theoretically: infinite number of energySame idea as spontaneous emission except we MAKE it happen by sending in an EM wave of frequency f0
A photon is given off with the energy E= h