SGER: Advanced Solid-State Laser with <20 Femtosecond PulseDuration (REU SUPPLEMENT)

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In this Small Grant for Exploratory Research, we propose to develop an all solid-state laser system capable of generating light pulses of unprecedented short duration. The technique of non-linear mode- locking can be used to generate femtosecond-duration pulses from a titanium-doped sapphire laser. The major limitation on the minimum pulse width obtainable from this laser is optical dispersion inside the laser cavity; i.e. different wavelengths of light take a varying time to complete a round-trip through the cavity of the laser. Since an ultrashort laser pulse must have a wide spectral width, a short pulse will not stay short if there is substantial dispersion in the laser cavity. By doing detailed calculations of dispersion, we have discovered a number of methods for minimizing it in this laser. We have already produced pulses of 25 femtoseconds duration-- a record for ultrafast lasers. We plan to expand upon this work to further advance the state-of-the-art in ultrafast laser technology. By designing a new laser, we expect to be able to demonstrate a simple and reliable source of 15-20 fs pulses. Our work promises to expand the utility of lasers for studying ultrafast processes in electronic materials and in chemical reactions.