Pulsed Frequency Stable Narrow Linewidth Lasers and Optical Remote Sensing

Usually people consider single mode pulsed lasers to be frequency stablized. But in a pulsed laser, mode selection is not equivalent to frequency stablization. This is because with any type of mode selection method or device, a long term frequency drift may occur from pulse to pulse due to thermal or mechanical disturbances of the cavity length. Furthermore, short term frequency drift (chirping) may occur within one pulse due to rapid refractive index variations of the active gain medium.