Novel compression technique shortens high-energy pulses to 10 femtoseconds
In a new approach to femtosecond pulse generation presented at CLEO `96 (paper CTuR5), a hollow cylindrical quart¥fiber filled with high-pressure noble gas spectrally broadens high-energy pulses that are subsequently recompressed by conventional prism pairs to durations as short as 10 fs. Researchers at the Polytechnic Institute of Milan (Milan, Italy) placed a 70-cm-long hollow quart¥fiber with an inner diameter of 140 µm inside a pressure chamber fitted with quart¥windows, then filled the chamber with argon, xenon, or krypton gas at high pressure. A Ti:sapphire laser with chirped-pulse amplification provided 140-fs, 660-µJ pulses that propagated through the chamber windows and the gas-filled waveguide. After exiting the waveguide and chamber, the pulses were recompressed by prism pairs.
Grou¥leader Orazio Svelto reported obtaining 13-fs pulses using argon gas at 7 atm. Xenon, with a higher Kerr nonlinearity, produced similar results at roughly 3 atm, but suffered from increased susceptibility to multiphoton ionization. Krypton gas at 2 atm yielded the best result, producing well-behaved 10-fs pulses with energies of 240 µJ.