For Student Groups
How does a laser work – and why does laser light have such extraordinary properties? In this course the participants assemble Pr:YLF lasers from individual optical components, characterize their laser systems and use the lasers in applications.
- 16 to 21 years
- 0.5 or 1 day
- Maximum number of participants
- Setup of the laser systems from individual components
- Adjustment of the laser resonators and starting the Pr:YLF lasers
- Investigation of Pr:YLF fluorescence
- Determination of the lasers wavelength using an diffraction grating
- Measuring the mean lifetime of the exited electrons in the Pr:YLF crystals (in full day course)
- Using the Pr:YLF lasers in applications (Michelson interferometer, measuring the speed of light, investigation of the coherence length, second harmonic generation) (in full day course)
The course begins with an introduction into the fundamentals of laser physics. Here, the atomic processes relevant for light amplification by stimulated emission of radiation and the technical realization of this concept in a laser system are particularly addressed. For the experiments, a praseodymium doped yttrium lithium fluorine (Pr:YLF) crystal is used 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 adjustment. In the experiment, the participants assemble the condenser optics for the pump light, use back reflexes and fluorescence light to set up and align the resonators and optimize the gain to get their lasers operating. Using a diffractive grating, they measure the wavelength of the laser radiation and investigate the fluorescence spectrum of the Pr:YLF. They discuss their results in view of the energy level diagram of Pr:YLF and the laser process.
In the full day course, the participants additionally use photodetectors and oscilloscopes to measure the mean lifetime of the exited electrons in the Pr:YLF. With this data they estimate the likeliness of stimulated emission. Additionally, they can use their lasers to set up a Michelson interferometer, investigate the coherence length of the laser light or measure the speed of light in a propagation time experiment.
Structure of atoms: charged particles, electron shell, nucleus; light as electromagnetic wave