1. Interaction of radiation with atoms and ions (I) Absorption- Stimulated emission E1E1 E2E2 W 12 =W 21 Spontaneous emission More definitionsCross section Absorption coefficient Gain

2. Interaction of radiation with atoms and ions (II) Line broadeningHomogeneous (Lorentz) Collisions Spont. emission (Gauss) Inhomogeneous Saturation Doppler Local field Phonons 2 1 1 2 High absorption Reduced absorption

3. Ray and wave propagation through optical media Gaussian Beam Matrix- formulation of Geometric Optics lens Material with index n ABCD law

4. Stable resonators Two-mirror resonator Stability condition General case Round trip matrix Gaussian beam solution Single passage matrix Frequencies Spectral width

5. Continuous Wave Laser Behavior Rate equations Threshold Stationary solution cw-laser

6. Transient Laser Behavior Phase velocity Group delay dispersion Q-switching:High lossesHigh population inversion Switching of lossesPulse (ns) Mode-lockingFrequency domain: Modes “in phase” Time domain: Pulse train, periodicity: Group velocity Group delay Gaussian

7. Properties of Laser beams Measurement: Michelson interferometer Temporal coherence Spatial coherence Measurement: Young’s double slit interferometer Temporal coherence: monochromaticity Spatial coherence: directionality Laser: good temporal coherence if monomode Laser: good spatial coherence if one transverse mode Thermal light: Brightness: For a Gaussian beam (high brightness) Laser and thermal light have different statistical properties different high-order coherence