Programmable chirp compensation for 6-fs pulse generation with a prism-pair-formed pulse shaper

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Abstract
We describe a TF5 prism-pair-formed pulse shaper for programmable pulse chirp compensation. The advantages of this kind of pulse shaper are: (1) very broad bandwidth of transmission; (2) smaller losses; and (3) no requirement for a large-size spatial light modulator (SLM) if the input spectrum is very broad. In our experiment, an ultrabroad spectral (500-1000 nm) pulse is produced by launching 1-kHz, 30-fs, 400-/spl mu/J pulses at 780 nm into an argon filled glass capillary fiber at the gas pressure of 2.0 bar. The fiber has an inner diameter of 140 /spl mu/m and a length of 60 cm. The chirped pulse is first precompressed by a pair of BK7 prisms with a separation length of 65 cm and then directed into the prism-pair-formed pulse-shaping apparatus with a 128-pixel SLM, which provides quadratic and cubic phase compensation. When the quadratic and cubic phases are -330 fs/sup 2/ and +2000 fs/sup 3/, respectively, at the wavelength of 760 nm, an ultrashort optical pulse of 6 fs (FWHM) is generated. This is, to the best of our knowledge, the shortest optical pulse ever compressed using the SLM pulse-shaping technique.