Generation of broadly tunable coherent radiation in the ultraviolet using nonlinear optical interactions
Weaver, Edward Greenfield
Tittel, Frank K.
Master of Science
A CW tunable coherent UV source capable of broad wavelength coverage from 26 nm to 4 run with a maximum output power in excess of 8 pW and a linewidth of less than .3 nm has been developed for use in spectroscopy. This source incorporates both second harmonic generation and sum frequency mixing to convert powerful tunable CW visible dye outputs into tunable UV outputs. The final system uses SHG of Rhodamine 6G and Oxazine 1 dye laser outputs and sum frequency mixing of these outputs with the high power fixed frequency lines of argon and krypton ion lasers to cover the UV range from 26 to 39 nm. The sum mixing technique allows the system incorporating these two strong dyes to cover a much broader range than would be allowed just by frequency doubling the output of these dyes and thereby avoids the use of many less efficient, short lifetime, and expensive dyes required in a SHG only system. Design schemes and optimizable parameters for this tunable source are described. A computer program based on the Boyd and Kleinman theory for focused Gaussian nonlinear interactions has been developed to calculate NL optical crystal parameters and predict NL conversion efficiencies over the tuning range of a NL crystal. Experimental results are presented and shown to be in agreement with this theory.