Publication Details
Werner Vandermeiren, Jan Cornelis

Book Anthology


The quality of laser based material processing is, among others, strongly affected by the spatio temporal characteristics of the incident laser radiation. As a result, there is a growing interest in laser pulse generation, laser pulse detection and the visualization of the (time dependent) laser beam intensity distribution. In this work we present opto-electronic semiconductor based devices targeting theCO2 laser spectrum. The focus of this thesis is twofold. On the one hand we investigated a novel evanescent wave modulator for Q switched laser pulse generation. On the other hand we focused on the visualization of the spatio temporal behavior of CO2 laser radiation by exploiting the thermo electric (Seebeck) effect in doped semiconductors (e.g. n-GaAs, n-Si). Special attention is paid to the multi physics modeling, the design parameter optimization process and the experimental validation of the devices. In the context of laser pulse generation, we furthermore studied the CO2 laser dynamics in function of different laser and modulator parameters. The principle of transverse laser mode switching or partial spatial modulation is presented as a novel means to improve the Q switching performance of most existing modulator principles and as an enabling technology for the RC time constant limited evanescent wave modulator. In the context of laser pulse monitoring, developments towards a high power (multi-kW) CO2 laser beam profiler are presented. This includes the investigation, implementation and demonstration of special techniques for thermal cross-talk reduction and beam shape recovery. Implementations of one dimensional focal plane arrays (FPA's) are shown.