Generation of Tunable Ultraviolet Pulses Using Gas Ionization By Chirped Two-Color Pulses

We propose a method for generating pulses of ultraviolet radiation with stable phase and tunable frequency. The method is based on gas ionization by two-color laser pulses with frequency chirp of opposite sign and variable time delay. Changing the time delay allows simple tuning of the generation frequency near the fourth harmonic of the fundamental field.