Enhanced generation of vacuum-ultraviolet radiation by four-wave mixing in mercury using pulsed laser vaporization

• Published in: Applied physics. B, Lasers and optics Vol. 89; no. 2-3; pp. 223 - 229
• Main Authors: CHENAIS, S, FORGET, S, PHILIPPET, L, CASTEX, M.-C
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01.11.2007
• Subjects: Beams (radiation); Density; Exact sciences and technology; Excimer lasers; Four-wave mixing; Frequency conversion ; harmonic generation, including high-order harmonic generation; Fundamental areas of phenomenology (including applications); Heating; Laser ablation; Laser-plasma interactions; Lithography; Mercury; Nonlinear optics; Optical sources and standards; Optics; Phase conjugation, optical mixing; photorefractive and kerr effects; Physics; Physics of gases, plasmas and electric discharges; Physics of plasmas and electric discharges; Vaporization; Visible and ultraviolet sources; Four-wave mixing; Ultraviolet sources; Lithography; Pulsed lasers; Ultraviolet radiation; Ambient temperature; Radiation sources; Laser plasma interaction; Excimer lasers; Two-photon processes; Gas lasers; Mercury; Nonlinear optics
• ISSN: 0946-2171; 1432-0649
• DOI: 10.1007/s00340-007-2782-8

The efficiency of a coherent vacuum ultraviolet (VUV) source at 125 nm, based on two-photon resonant four-wave mixing in mercury vapor, has been enhanced by up to two orders of magnitude. This enhancement was obtained by locally heating a liquid mercury surface with a pulsed excimer laser, resulting in a high-density vapor plume in which the nonlinear interaction occurred. Energies up to 5 Delta *mJ (1 kW peak power) have been achieved while keeping the overall mercury cell at room temperature, avoiding the use of a complex heat pipe. We have observed a strong saturation of the VUV yield when peak power densities of the fundamental beams exceeded the GW/cm2 range, as well as a large intensity-dependent broadening (up to ~30 cm-1) of the two-photon resonance. The source has potential applications for high-resolution interference lithography and photochemistry.