Abstract

The advantage of single axial mode Q-switched lasers for nonlinear optics and high resolution spectroscopy has been known since the invention of lasers. Single mode operation has proved difficult to achieve primarily because of the high gain and resultant short pulse build-up time of the laser photon flux in the lower ns-range. The standard performance to achieve single mode operation of a pulsed oscillator is to seed with a continuous wave single frequency laser. The methods to control actively the cavity length to match the resonance criteria for the seed wavelength are either based on measurements of the pulse properties like the pulse built-up time or measurements of a frequency shifted interference signal down into the 100 MHz-range. Either method operates via a servo system that adjusts the cavity length without an exact reliable single frequency operation.

© 2019 IEEE