Application of Laser Resonance Saturation to the Development of Efficient Short Wavelength Lasers

摘要

Laser saturation of an atomic resonance transition represents an important new mode of coupling laser energy into a gas or plasma. The basic mechanism in either case is superelastic collisional heating of free electrons. For a gas various seed ionization processes precede this interaction. During the past year we have developed a computational code for mapping the three dimensional nature of this interaction. This is required because this strong interaction invariably distorts and attenuates the laser pulse as it propagates through the medium being excited. We have also developed a new experimental facility for studying this interaction and have recently completed our first spectroscopic measurements of the electron temperature produced in a sodium plasma created through laser resonance saturation. This temperature appears to be somewhat lower than predicted by our computer simulation and we are currently attempting to reconcile this difference. Also within the past year we have discovered that attenuation of the laser pulse is a maximum when the laser is detuned by about 0.5 nm from either of the resonance lines.