New broad spectrum autocorrelator for ultrashort light pulses based on multiphoton photoemission

A prototype autocorrelator device for measuring the pulse width of ultrasho rt laser pulses in the picosecond and femtosecond regimes has been construc ted. The device is based on multiphoton induced ionization of electrons fro m a charged metal surface mounted on a vibrating silica fiber, which is an entirely different physical principle from those employed by existing metho ds for ultrashort pulse characterization, e.g., streak cameras or second ha rmonic generation. The new method distinguishes itself from existing techni ques in that it is, in principle, applicable to a very wide range of wavele ngths, from the far ultraviolet to the infrared, requires no special optica l orientation of a nonlinear crystal, and can be used for both femtosecond and picosecond pulses. The prototype device has been successfully applied t o 532 nm laser pulses with a similar to 20 ps pulse width, and preliminary work shows it is applicable to femtosecond pulses as well. (C) 2000 America n Institute of Physics. [S0034-6748(00)00304-X].