Interference Patterns Produced By a Mach-Zehnder Interferometer and A multiline HF Laser

The fringe pattern produced by a Mach-Zehnder interferometer illuminated with the light from a hydrogen fluoride HF laser operating on a large number of laser lines was investigated. Emphasis was placed on the intensity variations of the infrared fringes that are observed when one element of the interferometer is translated, thereby changing the length of one optical path. An intensity maximum similar to white-light fringes is observed when the two arms of the interferometer have equal optical lengths. The experimental results are compared with numerically predicted fringe patterns calculated from the spectral content of the illuminating laser beam. A method is suggested for actively controlling the phases of a number of parallel HF laser amplifiers in high-power phased-array devices.