December 26, 2016
The “Photon Beams and Optics” group of CANDLE SRI has designed and installed a new optical setup for studies and applications of diverse time- and phase-dependent optical phenomena at DELTA Laboratory. As a primary employment of the new setup, the 3rd harmonic generation (THG) is accomplished by frequency mixing of fundamental and second harmonic beams of AREAL “s-pulse” laser, already exploited at DELTA. Along with the infrared (IR,1030nm) and visible (green, 515 nm) beams, the new source at ultraviolet (UV) wavelength of 343 nm will be used for specific nonlinear optical experiments, as well as for material processing applications at laser microfabrication station.
The new setup is an assembly of two variable delay lines with a number of polarizing and nonlinear optical elements providing a delicate control of direction, relative phase, as well as the polarization and energy of both infrared and visible pulses. Due to the precise optomechanical control, in particular, a collinear propagation of infrared and visible beams with separately controllable parameters is achieved along an extensive path towards the stage of microfabrication station. As a result, frequency mixing can be accomplished either before or on the stage of microfabrication station. By tuning the energy, polarization, and temporal overlap of the pulses, the highest conversion efficiency of the 3rd harmonic generation is obtained for each configuration, providing a powerful ultraviolet source with variable pulse duration in the range of 400 fs—8 ps.