Femtosecond UV Laser Pulse Expander

The UV portion of the spectrum is gaining interest for military applications both for its unique spectral window for remote sensing and for the identification of targets such as trace amounts of explosives, chem/bio agents, and toxic chemicals. Powerful, fieldable laser sources are required for most sensing applications. Ultrafast lasers represent a unique capability because pulse widths are short, and can be varied from less than 100 fs to over 1 ns by simply dispersing the pulse in time using commonly used stretcher/compressor technology used in ultrafast amplifiers. However, because ultrafast amplifiers are mostly used at IR wavelengths, stretcher/compressor technology has been optimized for these wavelength regions. Ideally, and because different chemical and biological processes occur on various sub-nanosecond time scales, the pulse width should be variable in order to optimize the detection of the material of interest. The variability in pulse width also allows the incident energy on target to be easily and predictably varied. Consequently, the pulse width adjustment must be agile over a range of pulse widths. This Phase I effort is designed to demonstrate feasibility of agile stretcher technology that can change UV ultrafast laser characteristics rapidly for UV remote sensing needs.