Abstract

Difference-frequency generation (or optical rectification) is used to transform the beam emitted from a 10 fs Ti:sapphire laser into a coherent infrared (or THz) beam. Such a beam has a harmonic frequency-comb spectrum, the elements are exact harmonics of the laser's repetition rate f_r ≈ 125 MHz. We employ a multiheterodyne detection scheme¹ that allows to convert the beam's amplitude and phase spectrum into a radiowave spectral replica that is easily measured: since interference/sampling is self-scanned in the pure time domain—obleviatingh any moving mirror—spectra are recorded in very short acquisition time <1μs and in rapid sequence >1 kHz.

© 2007 IEEE