Erbium Laser Developement and Applications

This group is concerned with the modelling, development and applications of different erbium laser systems - flashlamp pumped as well as diode pumped.

Erbium ions emit radiation at different wavelengths between 2,69 and 2,94 µm, dependent on the host material. The development of pulsed solid-state lasers emitting in the 3 µm wavelength range has been particularly stimulated by a variety of applications in medicine. High absorption by tissue water (10⁴ cm^-1) in this wavelenght range makes erbium lasers a very precise instrument in surgery. The main field of application is in ophthalmic surgery, especially for cataract surgery, but different micro-surgery applications are also of interest.


Cataract surgery - the treatment of grey, opaque eye lenses - is one of the most commonly performed medical operations  (500.000 p.a. in Germany). This and the manifold advantages of lasers surgery compared to common ultrasonic method are the main reasons for improving laser systems and providing adequate output parameters. To achieve these output parameters, modelling of laser material parameters like niveau lifetimes or thermal distribution inside laser crystalls is necessary. Furthermore to improve phacoemulsification -the treatment of opaque eye lense during cataract surgery- investigations on laser-tissue interactions must be carried out.

The Erbium Laser Group has developed a high-repetition-rate, high-average-power, quasi-cw diode-pumped erbium laser system designed for use in cataract surgery. Figure 1 shows the setup of this Er:YAG laser. With this folded TIR-cavity laser, more than 3.5 W output power at up to 500 Hz repetition rate has been achieved. Due to these parameters, this laser system is competitive in comparison to the common ultrasonic method. Investigations on the further improvement of laser parameters and on the treatment of lens samples and lenses are being carried out at the moment.