Measuring Dispersion in Laser Cavity Mirrors Using White-Light Interferometry

Terahertz radiation is an emerging field that has far reaching applications. There is a need for portable and affordable terahertz sources that may be used for detection of structural weaknesses in aerospace composites. One possibility for terahertz generation is a femtosecond Cr:LiSAF laser. However, controlling intracavity dispersion is necessary in order to get the ultrashort pulses needed to generate terahertz radiation. This research measures dispersion of the chirped femtosecond intracavity mirrors by employing white-light interferometry and explains the theory behind the curve-fitting process used to calculate dispersion. To compensate for the narrow reflectivity band of the mirrors, a CaF2 (calcium fluoride) window was used to increase the number of spectral fringes in the interferogram.