Lasers are light amplifiers, based on stimulated emission. In this course, the participants investigate how the energy of individual photons is amplified in quantized atomic processes and how this finally yields a macroscopic intensity distribution that can be described by a standing wave. The course comprises experiments in atom and quantum physics, wave physics and energy and relates high school relevant contents to applications and current research.

3 to 4 days, max. 12 participants

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  • Wave properties of light (diffraction and interference)
  • Absorption, emission, fluorescence (energy levels and photons)
  • Measuring the radiant flux with photodetector and oscilloscope (quantization of energy flux)
  • Setup and characterization of Pr:YLF lasers (fluorescence spectrum, mean lifetime of the electrons in the excited state, wavelength, coherence length, spiking)
  • Energy conversion in lasers (atomic and macroscopic efficiency)
  • Laser applications (interferometry, measuring the speed of light, wavelength selection, second harmonic generation)

Course description:

In the first part of the course, the participants use classical light sources for experiments on the wave properties of light (diffraction and interference) and on quantized energy absorption and release of different substances during absorption, emission and fluorescence. Measuring the radiant flux of different light sources and determining the mean lifetime of electrons in the excited state they experience that energy can be stored in a substance for a certain time – a prerequisite for light amplification by stimulated emission.
For the laser experiments the participants use praseodymium doped YLiF4 (Pr:YLF) as active laser medium. Pr:YLF exhibits an absorption maximum at 444 nm and an emission maximum at 640 nm, thus both, the pump light and the laser light are visible allowing a reliable setup and adjustment of the laser system. The participants discuss the results of the extensive characterization of the lasers in the wave view (wavelength, coherence length) and in the particle view (fluorescence spectrum, mean lifetime). The experimentally determined efficiency of energy conversion in the laser is assessed considering atomic and macroscopic processes.
After the successful characterization, the participants use “their” lasers in applications (measuring the speed of light in air, measuring the dependence of the speed of light from the air pressure) and perform advanced experiments like wavelength selection or second harmonic generation. Furthermore, they get insights into current research with lasers during a lab visit in the physics faculty of Göttingen University.
For questions regarding the course content, please contact the team of the physics department.

Addressed topics:

Structure of atoms: charged particles, electronic shell, nucleus
Light as electromagnetic wave
Waves and quanta

 The course is funded by ICASEC.