Application of Wavelet Transform for Analysis of Radiated Electromagnetic Interference in a High Power Terawatt Laser Setup

This paper reports the wavelet transform based time-frequency-intensity analysis of radiated electromagnetic noise generated by a flash lamp pumped terawatt class of high power pulsed laser. High power pulsed solid state lasers are widely used for research and industrial applications. Main electrical components of these lasers are flash lamp power supplies, electro-optic switches, timing and synchronization circuits, and control system. These sub-systems operate at different instants of time during the laser operation cycle. Range of the time delays between switching of various blocks in the system vary from 100 ns to hundreds of microseconds. The electromagnetic noise generated by the laser is pulsed type single shot event, which is measured in time domain. The conventional technique of Fourier transform generate frequency spectrum of the electromagnetic interference (EMI), however, it loses the time information and does not reveal the noise contributions by each of the sources and subsystem localized in time. In this work, wavelet transformations are applied on the measured signals to estimate frequency content of the noise contribution by each source and to generate the time-frequencyinformation. This technique helps in better identification and characterization of the electromagnetic noise sources in a high power laser chain and to achieve the growing demands for electromagnetic compatibility (EMC).