Virtual laboratory experiment: Simulation of modes of a laser resonator
M. Gruber, A. Borchmann, J. Jahns
As a distance teaching institution the FernUniversit¨at Hagen aims at offering as many teaching materials and courses as possible in a format that does not require the personal presence of a student at the Hagen campus. This task is quite challenging for lab courses, especially in Electrical Engineering, because their purpose is to make students familiar with practical problems as well as the work approaches and instruments of the professional (real) world. Our approach to achieve this goal is to create virtual environments that provide room for hands-on exercises under rather realistic conditions.
Here we present a new mod- ule of a virtual lab course on photonics. It deals with the modal characteristics of the radiation emitted by a laser. The module is writ- ten in Java langage in the form of an applet and can be downloaded and executed off-line by a student who has registered for the lab course.
Starting the applet opens a window in which a laser res- onator and an observation screen are shown schemati- cally (cf. Fig. 1). The ge- ometry of the resonator and the distance between screen and resonator can be ad- justed via the buttons in the lower part of the window.
Depending on the geometry a certain number of (spa- tial) laser modes can exist which can be selected with the buttons at the top. The three diagrams in the upper part are cross sections of the screen and display graphs of the amplitude distribution in x- and y-direction and a 2-D plot of the intensity pro- file. Mathematically the ap- plet is based on the Hermite- Gaussian beam approxima- tion. In Fig. 1 the (0,0) and the (2,3) mode are shown ex- emplarily.
Fig. 1: Simulation of Hermite-Gaussian modes (0,0) and (2,3).
